Dissertations / Theses: 'Wine sensory'

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Kallithraka, Stamatina. "Sensory and instrumental astringency determination in wine." Thesis, University of Surrey, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336989.

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Van, Antwerpen Lindi. "Chemical and sensory profiling of dry and semi-dry South African Chenin blanc wines." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/71853.

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Thesis (MSc)--Stellenbosch University, 2012.
ENGLISH ABSTRACT: Chenin blanc wine is of economic importance to South Africa and a range of diverse dry and semi-dry wines are locally produced in this genre. Currently, the use of three distinctly different style names, each aimed at providing consumers with information about the flavour of the wines, is encouraged by the South African (SA) wine industry. The styles are fresh and fruity (FF), rich and ripe unwooded (RRUW) and rich and ripe wooded (RRW). Feedback from retail sectors over the past few years, however, repeatedly suggested that the style names are perceived as confusing by SA consumers. This master study was undertaken to re-evaluate the FF, RRUW and RRW style classification, based on both the volatile fermentation-derived aroma composition and the sensory attributes of a set of wines containing all the styles under investigation. For the purposes of chemical profiling, a set of 105 commercial Chenin blanc wines, selected to be representative of these three styles and originating from the major SA wine producing areas, were analysed by Gas Chromatography (GC) to quantify fermentation-derived volatile aroma compounds in the wines. ANOVA performed on the chemical data showed that 29 compounds represent significant differences between at least two of the 3 styles (FF, RRUW and RRW). Principal component analysis (PCA) of the volatile compounds showed a large degree differentiation between FF and RRW wine styles, however, RRUW wine styles overlapped with the other two styles. Considering vintage effects, ANOVA indicated no significant differences within FF (vintages 2009 and 2010) and RRW (vintages 2008 and 2009) styles, whereas only 2 esters and 4 terpenes showed significant differences between the three wine producing regions investigated for this purpose, Paarl/Wellington, Breede River and Stellenbosch. Volatile aroma compounds generated for Chenin blanc were included in the Winetech database consisting of the most important cultivars of South Africa. Combining the data for the volatiles for Chardonnay and Sauvignon blanc from this database and the data for Chenin blanc obtained in this study, a PCA indicated a clear separation between Chenin blanc and the other two white cultivars. Sensory evaluation of the style classification was done by two separate sensory tests. Firstly, a sorting task was performed by wine industry experts to categorise 21 Chenin blanc wines (FF, RRUW and RRW) based on their similarity. The results showed a differentiation between FF and RRW styles, however, RRUW was mostly classified together with FF wines. This indicated a possible continuum between the three styles, as opposed to three distinct different categories, currently suggested by the style names. The second sensory analysis test, Descriptive Sensory Analysis (DSA), was performed by a trained panel to generate sensory profiles for 42 wines. ANOVA of the flavour attribute intensities between different styles once again showed significant differences between FF and RRW, with RRUW wines forming a continuum between the FF and RRW styles. These results provide valuable information that could be used by the wine industry for labelling purposes.
AFRIKAANSE OPSOMMING: Chenin blanc is van ekonomiese belang vir Suid Afrika en ‘n wye reeks droë en semi-droë wyne word plaaslik geproduseer in hierdie kategorie. Tans word die gebruik van drie duidelike verskillende stylbenamings, elkeen daarop gemik om aan die verbruiker inligting te verskaf oor die geur van die wyn, deur die Suid Afrikaanse (SA) wynindustrie aangemoedig. Die style is vars en vrugtig, ryk en ryp ongehout en ryk en ryp gehout. Terugvoer van die handelssektor oor die afgelope aantal jare, het daarop gedui dat die stylbenamings tot verwarring onder SA verbruikers lei. Hierdie meestersstudie is onderneem om die stylklassifikasie, vars en vrugtig, ryk en ryp ongehout en ryk en ryp gehout, te her-evalueer op grond van die vlugtige aroma komponente wat tydens die fermentasie proses gevorm word, asook die sensoriese eienskappe van ‘n verteenwoordigende stel wyne van elk van die style wat ondersoek is. Vir die doel van die chemiese profilering, is ‘n stel van 105 kommersiële wyne, wat geselekteer is om verteenwoordigend te wees van die drie style ondersoek en ook afkomstig is van die vernaamste SA wynproduserende streke, gebruik. Die wyne is met behulp van gas chromatografie ontleed om die vlugtige komponente wat van die fermentasie proses afkomstig is, te kwantifiseer. Die analise van variansie, het getoon dat 29 komponente statisties beduidend verskil het tussen die drie style. Hoofkomponent analise van die vlugtige komponente, het getoon dat die vars en vrugtige wyne en ryk en ryp gehoute wyne, duidelik onderskeibaar was van mekaar op grond van die vlugtige data, maar die ryk en ryp ongehoute wyne het met die ander twee style oorvleuel. In terme van oesjaar effekte, was daar geen beduidende verskille in die aroma profiele van die vars en vrugtige styl (oesjare 2009 en 2010) en ryk en ryp ongehoute styl (oesjare 2008 en 2009) nie, terwyl die konsentrasie van slegs twee esters en 4 terpene statisties beduidend verskil het tussen die wynproduserende streke Paarl/Wellington, Breederivier en Stellenbosch. Resultate van die gekwantifiseerde vlugtige komponente is in die databasis van Winetech gevoeg, waar die konsentrasies van soortgelyke komponente van die vernaamste SA wynkultivars reeds vervat is. Hoofkomponent analises van die gekombineerde resultate vir Chenin blanc, Chardonnay en Sauvignon blanc wyne, het getoon dat daar ‘n duidelike verkil tussen Chenin blanc en die ander twee wit wynkultivars was. Die sensoriese evaluerings is uitgevoer deur van twee verskillende metodes gebruik te maak. Eerstens is 21 wyne (met al drie style verteenwoordig) deur wynindustrie eksperts gesorteer op grond van die waargenome eendersheid van die onderskeie wyne en die resultate is grafies geprojekteer. Die resultate het getoon dat daar ‘n duidelike verskil waargeneem is deur die assessors tussen die vars en vrugtige styl en ryk en ryp gehoute styl. Die ryk en ryp ongehoute wyne het in die analises meer met die vars en vrugtige style geassosieer, as die ryk en ryp gehoute wyne. Die tweede sensoriese metode is uitgevoer deur sensoriese paneel wat vir die doel van hierdie studie opgelei is om die geur eienskappe van 42 wyne (al drie style verteenwoordig) te profileer. Analise van statistiese beduidende verskille tussen die voorkoms van die geurkomponente en hul intensiteite vir elke styl, het weereens aangedui dat daar ‘n kontinuum bestaan tussen die style. Hierdie resultate kan van waarde vir die wynindustrie wees in besluite rakende etikettering.

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Sanborn, Melissa. "The impact of fining on the chemical and sensory properties of Washington State Chardonnay and Gewürztraminer wines." Online access for everyone, 2008. http://www.dissertations.wsu.edu/Thesis/Summer2008/M_Sanborn_081308.pdf.

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Brown, Rachel Christine, and rcbrown@adam com au. "gamma-Lactones in wine: Synthesis, quantification and sensory studies." Flinders University. School of Chemistry, Physics and Earth Sciences, 2007. http://catalogue.flinders.edu.au./local/adt/public/adt-SFU20080226.234630.

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gamma-Lactones are found in a wide variety of food and beverage products, in particular grapes and wine. This thesis details the work completed on some gamma-lactones in wine: their synthetic preparation, development of quantification methodologies and sensory studies. Chapter 1 outlines the history of the Australian wine industry from the arrival of the first vines on the First Fleet in 1788 with Captain Arthur Philip. This chapter provides: an overview of Australias position in the world of grape and wine production; an analysis of the export arm of the industry; and a look at the different wine producing regions around the country. The latter part of the chapter focuses on the different volatile compounds found in wine. Part A: Chapter 2 provides an overview on the history of barrel manufacture and the use of oak wood in cooperage, with an emphasis on oaks well known ability to impart desirable characteristics to wine through the extraction of volatile aroma compounds. This chapter provides a summary of these odorants with a particular emphasis on the oak lactones. Previous sensory studies and synthetic work are discussed. Of great importance to this work are the recent advancements in 1,2-dioxine chemistry, highlighted in this chapter. Chapter 3 details the synthetic work completed for the preparation of all four possible oak lactone stereoisomers. A suitably substituted racemic 1,2-dioxine featured as the common intermediate and enabled preparation of the gamma-lactone moiety upon reaction with a chiral malonate diester and separation of the diastereomers by column chromatography. A key step involved the decarboxylation of the ester cleaved gamma-lactone diastereomers, which could be directed to give either the cis- or trans-products. Standard chemical transformations were then utilised to produce the desired stereoisomers of oak lactone. Chapter 4 describes the results from the sensory studies that were completed on the synthetic oak lactone samples. Odour detection thresholds were measured in both a white and a red wine. The thresholds in the former medium were calculated to be 24 ug/L, 172 ug/L, 132 ug/L and 305 ug/L, while in the latter medium the thresholds were calculated to be 57 ug/L, 380 ug/L, 175 ug/L and 285 ug/L, for (4S,5S)-cis-, (4S,5R)-trans-, (4R,5R)-cis- and (4R,5S)-trans-oak lactone, respectively. Difference testings were completed on the pairs of enantiomers and also on mixtures of the nature-identical isomers: between the cis-enantiomers a significant difference was found at the 99% confidence level, while between the trans-enantiomers and also the mixtures of cis- and trans-isomers little difference was observed. Chapter 5 contains the experimental procedures for Part A. Part B: Chapter 6 discusses the sensory properties of some gamma- and delta-lactones, with the focus on a series of five-alkyl substituted gamma-lactones: gamma-octalactone, gamma-nonalactone, gamma-decalactone and gamma-dodecalactone. Topics covered in this chapter include chirality, biosynthetic pathways and quantification results in wine from previous studies for these gamma-lactones. Chapter 7 concerns the method development for the quantification of gamma-lactones in wine using a stable isotope dilution assay (SIDA). Deuterated analogues were prepared from commercially available racemic gamma-lactones for use as internal standards. Initially a head space solid-phase microextraction (HS SPME) method was developed using d5-standards; however, analysis of bottled wine samples revealed the presence of co-eluting compounds that contained several of the selected ions. Thus an alternative method was developed using d7-standards, with a specific focus on sample clean-up, via solid-phase extraction (SPE). Using this procedure, 44 white and 120 red wines were analysed for their gamma-lactone content. The lactones were found to be significantly more common in the red wines, with gamma-nonalactone the most abundant lactone in this series. Chapter 8 deals with the extension of the SIDA method, as developed in Chapter 7, for use with a chiral gas chromatography column. Optically pure standards were prepared, from either L- or D-glutamic acid, and used to determine the order of elution of the enantiomers. A method was developed for the quantification of the individual enantiomers of gamma-octalactone, gamma-nonalactone, gamma-decalactone and gamma-dodecalactone. The enantiomeric distribution of gamma-nonalactone was investigated in 34 red wines; the (R)-stereoisomer was found to be dominant with an average of 59%, although there were wines analysed that did contain the (S)-stereoisomer in greater amounts. Chapter 9 describes the results from the sensory studies that were completed on the individual enantiomers of the gamma-lactones. Odour detection thresholds were measured in a red wine. The thresholds were calculated to be 238 ug/L, 285 ug/L, 34 ug/L and 8 ug/L for the (R)-enantiomers, while the thresholds were calculated to be 135 ug/L, 91 ug/L, 47 ug/L and 39 ug/L for the (S)-enantiomers, of gamma-octalactone, gamma-nonalactone, gamma-decalactone and gamma-dodecalactone, respectively. Chapter 10 contains the experimental procedures for Part B. Chapter 11 contains the appendices, followed by the references in Chapter 12.

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Botha, Janita J. "Sensory, chemical and consumer analysis of Brettanomyces spoilage in South African wines." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/4141.

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Thesis (MSc Food Sc (Food Science))--University of Stellenbosch, 2010.
ENGLISH ABSTRACT: This study focussed on the sensory effects of the main volatile compounds produced by Brettanomyces yeast causing spoilage in wine. This research firstly aimed to determine the detection thresholds of eight Brett-related spoilage compounds in wine. The second aim was to determine the sensory effect of the four most important Brett-related compounds when present individually in wine. The third aim was to determine the sensory effects of these four compounds when present in wine in a range of combinations, and to further investigate their effect on consumer liking. Finally, this project aimed to investigate the incidence of these compounds in a small range of South African wines. The sensory detection thresholds of 4-ethylphenol, 4-ethylguaiacol, 4-ethylcatechol, 4- vinylphenol, 4-vinylguaiacol, isovaleric acid, isobutyric acid and acetic acid were determined. Apart from 4-ethylcatechol, these values generally agreed well with recent literature where values determined in wine are available. However, the discrepancies highlighted the importance of the effect of the medium (wine) when determining sensory detection thresholds. The use of the median as alternative calculation method was also investigated, and it was found that this method gives more insightful results than the standard American Society of Testing Materials (ASTM E679-04) method. Four compounds, namely 4-ethylphenol, 4-ethylguaiacol, 4-ethylcatechol and isovaleric acid were profiled individually in wine using a trained sensory panel. It was found that all four compounds caused a suppression of the natural berry-like character in the wine, which induced a sick-sweet character. 4-ethylphenol contributed Elastoplast™ and leather aromas in the wine, both of which are commonly associated with Brettanomyces taint. 4-ethylguaiacol added a medicinal aroma to the wine, and 4-ethylcatechol and isovaleric acid were responsible for savoury and pungent aromas, respectively. 4-ethylphenol, 4-ethylguaiacol, 4-ethylcatechol and isovaleric acid were also profiled in combination according to the central composite design. Several univariate and multivariate methods were applied to the dataset obtained. PARAFAC, a multiway method not widely utilized regarding sensory data, was applied to the data, the results of which were complementary to those obtained during univariate and multivariate analyses. It was found that there is a great deal of interaction between the four compounds profiled in terms of sensory effects. The most notable was the Elastoplast™ attribute, the intensity of which was affected by all four compounds. The pungent attribute was also affected by the 4-ethylphenol concentration. Consumer analysis revealed that some of the samples spiked with Brettanomyces-spoilage compounds were preferred to the unspiked (control sample). However, no further relationship could be found between consumer liking and either chemical composition or sensory profile. It is therefore speculated that consumer liking of Brettanomyces infected wine is driven by more complex sensory or socio-demographic factors. Finally, the concentration of 4-ethylphenol, 4-ethylguaiacol, 4-ethylcatechol, 4-vinylphenol, 4- vinylguaiacol, isovaleric acid, isobutyric acid and acetic acid was determined in a small set of South African wines, selected to contain a high proportion of wines spoiled by Brettanomyces. Significant correlations were found between 4-ethylphenol and 4-ethylguaiacol, as well as 4- ethylphenol and isovaleric acid. However, no correlation could be found between 4-ethylphenol and 4-ethylcatechol. It is speculated that this lack of relationship is due to the different precursor profiles present in the analysed wines. This study paved the way for future investigations on the sensory effects of Brettanomyces spoilage in Pinotage red wine.
AFRIKAANSE OPSOMMING: Hierdie studie het gefokus op die sensoriese invloed van die belangrikste vlugtige komponente wat deur die Brettanomyces gis geproduseer word en bederf veroorsaak in wyn. Eerstens is gefokus op die bepaling van die deteksiedrempelwaardes van agt Brett-verwante bederwende komponente. Die tweede doelwit was om die sensoriese invloed van vier van die mees belangrike Brett-komponente te bepaal wanneer hulle individueel in wyn voorkom. Die derde doelwit was om die sensoriese invloed van hierdie vier komponente te bepaal wanneer hulle in verskillende kombinasies in wyn voorkom, asook die effek daarvan op verbruikervoorkeur. Laastens is gepoog om die voorkoms van hierdie komponente in ‘n klein seleksie van Suid- Afrikaanse wyne te bepaal. Die sensoriese deteksiedrempelwaardes vir 4-etielfenol, 4-etielguaiacol, 4-etielcatechol, 4- vinielfenol, 4-vinielguaiacol, isovaleraatsuur, isobuteraatsuur en asynsuur is bepaal. Met die uitsondering van 4-etielcatechol het die waardes oor die algemeen goed ooreengestem met waardes wat onlangs in die wetenskaplike literatuur gepubliseer is. Die uitsonderings het egter die belangrikheid van die medium (wyn) gedurende die bepaling van sensoriese deteksiedrempelwaardes uitgelig. Die gebruik van die mediaan as ‘n alternatiewe berekeningsmetode is ook ondersoek en daar is gevind dat hierdie metode meer insiggewende resultate lewer as die standaard American Society of Testing Materials (ASTM E679-04) metode. Vier komponente naamlik 4-etielfenol, 4-etielguaiacol, 4-etielcatechol en isovaleraatsuur is individueel in wyn geprofileer met behulp van ‘n opgeleide sensoriese paneel. Daar is gevind dat al vier die komponente die natuurlike bessiekarakter in die wyn onderdruk terwyl dit aanleiding gee tot ‘n onnatuurlike soet karakter. 4-etielfenol is gekenmerk aan Elastoplast™ en leeragtige aromas in die wyn en beide van hulle word algemeen geassosieer met Brettanomyces bederf. 4-etielguaiacol het ‘n medisinale aroma tot die wyn toegevoeg en 4- etielcatechol en isovaleraatsuur het respektiewelik souterige (“savoury”) en sterk (“pungent”) aromas tot gevolg gehad. 4-etielfenol, 4-etielguaiacol, 4-etielcatechol en isovaleraatsuur is ook in verskeie kombinasies geprofileer volgens die sentrale saamgestelde ontwerp (“central composite design”). Verskeie enkelveranderlike en meerveranderlike statistiese analisemetodes is ook op die datastel uitgevoer. PARAFAC, ‘n meerrigtingsmetode wat nie normaalweg vir sensoriese analise data gebruik word nie, is ook uitgevoer op die data en die resultate was komplimentêr tot die van die enkelveranderlike en meerveranderlike analisemetodes. Daar is gevind dat, met betrekking tot sensoriese effekte, daar noemenswaardige interaksie tussen die vier komponente plaasvind. Die mees opmerklike hiervan was die Elastoplast™ aroma, waarvan die intensiteit deur al vier die ander komponente geaffekteer is. Verder is die sterk (“pungent”) aroma beïnvloed deur die 4-etielfenol konsentrasie. Verbruikersvoorkeur-analise het aangedui dat sommige van die monsters waarby Brettanomyces bederwende komponente gevoeg is, verkies word bó die kontrole-wyn. Daar kon egter geen verdere verband gevind word tussen die verbruiker se voorkeur en, nog die chemise komposisie of sensoriese profiele, van die wyn nie. Daar kan dus gespekuleer word dat verbruiker voorkeur van Brettanomyces bederfde wyn gedryf word deur meer komplekse en sosio-demografiese faktore. Laastens is die konsentrasies van 4-etielfenol, 4-etielguaiacol, 4-etielcatechol, 4-vinielfenol, 4- vinielguaiacol, isovaleraatsuur, isobuteraatsuur en asynsuur in ‘n seleksie van Suid-Afrikaanse wyne bepaal. Dié wyne is spesifiek so gekies sodat ‘n aansienlike aantal van hulle met Brettanomyces bederf was. Betekenisvolle korrelasies is gevind tussen 4-etielfenol and 4- etielguaiacol, sowel as 4-etielfenol en isovaleraatsuur. Daar is egter geen korrelasie tussen 4- etielfenol and 4-etielcatechol gevind nie. Daar word vermoed dat hierdie gebrek aan korrelasie te wyte is aan die voorloperkomponent profiele teenwoordig in die wyne. Hierdie studie het die weg gebaan vir verdere ondersoeke na die sensoriese effekte van Brettanomyces bederf in Pinotage rooi wyn.

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Coetzee, Carien. "Oxidation treatments affecting Sauvignon blanc wine sensory and chemical composition." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86321.

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Thesis (PhD(Agric))--Stellenbosch University, 2014.
ENGLISH ABSTRACT: This study focussed on the effect of oxygen on the chemical and sensory evolution of Sauvignon blanc wine under controlled oxidation conditions. The sensorial interactive effects between Sauvignon blanc varietal aroma compounds and compounds that typically arise during oxidation of white wines were also investigated. In the first research chapter the sensorial interactive effects of Sauvignon blanc impact compounds with aldehydes typically originating from oxidation of white wines were investigated. Four compounds, 3‐ mercaptohexan‐1‐ol (3MH), 3‐isobutyl‐2‐methoxypyrazine (IBMP), 3‐(methylthio)‐propionaldehyde (methional) and phenylacetaldehyde were added together in a model wine medium at varying concentrations. The concentrations chosen were according to those reported in literature to occur in Sauvignon blanc wines. The sensory effects of these compounds were profiled using a trained sensory panel. Compounds were first profiled individually and results showed that the change in comcpound concentration not only led to a change in intensity ratings but also in some cases a change in the descriptor. All four compounds in the same sample showed complicated interactive effects. Data were statistically analysed using relatively novel techniques such as statistical networks that allowed deeper insights into the interactions involved. Various observations were made such as the contribution of 3MH to the ‘green’ character of the wine, the potent suppressing abilities of methional on 3MH and IBMP and the additive effect of methional and IBMP contributing to the ‘cooked’ character of the sample. In the second research chapter the effect of repetitive oxidation on a fresh and fruity style Sauvignon blanc wine was investigated. Results showed the progress and evolution of aromatic and non‐aromatic compounds during an oxidative aging period. A large range of chemical analyses were conducted together with extensive sensory profiling. Results showed a decrease in volatile thiols responsible for the fruity nuances and an increase in oxidation‐related compounds, such as acetaldehyde, during the course of the oxidation. Sensory profiling showed the evolution of the wine aroma during oxidation. The wine evolved from a fresh and fruity wine to slight oxidation and then developed extreme oxidative characteristics. The Control samples (no oxygen added) developed a ‘cooked’ character which could indicate the formation of reductive compounds in these wines. Conversely, the wines that received a single dose of oxygen did not develop this flavour and were perceived to be more fresh and fruity than the Control samples. The evolution of the wine colour was also monitored using a spectrophotometer as well as a sensory panel and results suggest that the colour of the wine evolved before the disappearance of the pleasant aroma. The advantages and disadvantages of oxygen exposure to this type of wine style are discussed as well as the complexity of the wine matrix and sensory interactions occurring in the specific wine. The aim of the third research chapter was again to investigate further sensory interactions between Sauvignon blanc varietal aroma compounds and an oxidation‐related compound. After the observations reported in the second research chapter, the inclusion of acetaldehyde in an interaction study seemed to be of critical importance. Acetaldehyde can reach significant concentrations during oxidation and can have a detrimental effect on wine aroma. This interaction study included three compounds, 3MH, IBMP and acetaldehyde. Acetaldehyde was able to effectively mask the ‘green’ character of the sample, while it also enhanced certain fruity nuances when present at specific concentrations. 3MH was able to suppress the oxidising character of acetaldehyde when present at sufficient concentrations. The results from this study clearly showed the complexity of the wine medium and the interactions involved. It also highlighted the importance of performing these types of sensory studies in a simple medium opposed to a complex matrix such as wine. The effect of oxygen on various aspects of the wine was investigated and the combination of chemical and sensory data delivered some interesting conclusions also involving interactions that occurred. This study paved the way for future investigations on the sensory relationships of Sauvignon blanc aroma compounds and the role of proper oxygen management in the production of quality wines.
AFRIKAANSE OPSOMMING: Die doelwit van die studie was om die effek van gekontroleerde oksidasie op die ontwikkeling en verloop van verskeie chemiese komponente asook die ontwikkeling van die sensoriese profiel van ‘n Sauvignon blanc wyn te ondersoek. Bykomende studies ondersoek die interaksie/wisselwerking tussen aromakomponente in ‘n eenvoudige matriks. Interaksies tussen spesifieke Sauvignon blanc kultivargeassosieerde aromakomponente en komponente wat normaalweg tydens die oksidasie van witwyne ontwikkel, word ondersoek. Die eerste navorsingshoofstuk het ten doel om die interaksie tussen tipiese Sauvignon blanc aromakomponente (of impakkomponente) met aldehiede wat normaalweg tydens oksidasie van witwyne ontwikkel, na te vors. Vier komponente is in ‘n modelwyn gevoeg teen verskeie konsentrasies, wat oor die algemeen in die literatuur gerapporteer is om voor the kom in Sauvignon blanc wyne. Die komponente wat ondersoek is, is: 3‐merkaptoheksanol (3MH), 3‐isobutiel‐2‐metoksiepirasien (IBMP), 3‐ (metieltio)‐propionaldehied (methional) en fenielasetaldehied. Die sensoriese effekte van die komponente is deur ‘n opgeleide sensoriese paneel geëvalueer. Komponente is eers individueel geanaliseer en die resultate het getoon dat dat die intensiteit van die spesifieke aroma verander namate die konsentrasie verander. In sommige gevalle het die beskrywende woord vir die aroma ook verander. Deur al vier komponente in dieselfde monster te voeg word die ondersoek gekompliseer. Die data is statisties geanaliseer deur gebruik te maak van relatiewe nuwe tegnieke soos statistiese netwerke wat dieper insig in die betrokke interaksies bewerkstellig. Verskeie waarnemings word gerapporteer onder andere die bydrae van 3MH tot die ‘groen’ karakter van die wyn, die kragtige onderdrukkingsvermoë van methional op 3MH en IBMP asook die opbouende effek van methional en IBMP wat bydra tot die ‘gekookte’ karakter van die monster. Die tweede navorsingshoofstuk is daarop gemik om die effek van herhalende oksidasie op 'n vars en vrugtige styl Sauvignon blanc wyn te ondersoek en om die vordering en ontwikkeling van aromatiese en nie‐aromatiese komponente gedurende hierdie tydperk te analiseer. ‘n Wye reeks chemiese komponente is geanaliseer tesame met omvangryke sensoriese analise. ‘n Afname in die vlugtige tiole, wat verantwoordelik is vir die vrugtige geure, is gevind tesame met ‘n toename in oksidasie‐verwante komponente (soos asetaldehied). Sensoriese ondersoeke toon ook die evolusie van die wynaroma tydens oksidasie. Die wyn het ontwikkel van ‘n vars en vrugtige styl na effense oksidasiegeure waarna ekstreme oksidasiekarakters waargeneem is. Die Kontrole monsters het ‘n ‘gekookte’ karakter ontwikkel wat ‘n aanduiding van die ontwikkeling van ‘reduktiewe’ komponente in hierdie wyn kan wees. Aan die ander kant het wyne wat een suurstofdosering ontvang het, geen van hierdie geure ontwikkel nie en die wyn is as varser en vrugtiger beskryf in vergelyking met die Kontrole monsters. Die ontwikkeling van die wynkleur is ook gemonitor deur gebruik te maak van ‘n spektrofotometer asook 'n sensoriese paneel. Resultate stel voor dat die kleur van die wyn ontwikkel voor die aangename geure begin verdwyn. Die voor‐ en nadele van suurstofblootstelling aan hierdie tipe wynstyl word bespreek asook die kompleksiteit van die wynmatriks en sensoriese interaksies wat in hierdie spesifieke wyn voorkom. Die derde navorsingshoofstuk is weereens daarop gemik om die sensoriese interaksie tussen tipiese Sauvignon blanc kultivar‐geassosieerde aromakomponente en nog ‘n oksidasie‐geassosierde aromakomponent te ondersoek. Die resultate vanuit die tweede navorsingshoofstuk het die insluiting van asetaldehied in die interaksiestudie genoodsaak. Asetaldehied kan betekenisvolle konsentrasies tydens oksidasie behaal en kan ook nadelige effekte op wynaroma hê. Hierdie interaksiestudie het die volgende drie komponente ingesluit: 3MH, IBMP en asetaldehied. Asetaldehied het die ‘groen’ karakter van IBMP effektief gemaskeer terwyl dit die waarneming van die vrugtige aroma ondersteun en selfs verhoog het wanneer dit teen sekere konsentrasies teenwoordig was. 3‐Merkaptoheksanol het die oksidasiekarakter van asetaldehied onderdruk wanneer dit teen genoegsame konsentrasies teenwoordig was. Die kompleksiteit van wyn as ‘n navorsingsmedium is duidelik vanuit die studie veral in die ondersoeking van interaksie‐effekte tussen komponente. Die belangrikheid van die gebruik van 'n eenvoudige medium teenoor ‘n komplekse medium vir soortgelyke studies is dus duidelik. Die effek van suurstof op verskeie aspekte van witwyn is ondersoek en die kombinasie van chemiese en sensoriese data het interessante gevolgtrekkings gelewer. Die studie het die pad vir toekomstige studies gebaan in terme van sensoriese interaksies met betrekking tot Sauvignon blanc aroma. Die belangrikheid van oordeelkundige suurstofbestuur tydens die produksie van kwaliteit wyne is ook uitgelig.

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Bester, Inneke. "Classifying South African Chenin blanc wine styles." Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/18048.

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Thesis (MSc)--Stellenbosch University, 2011
ENGLISH ABSTRACT: South African Chenin blanc wine is characterised by its style diversity and has been receiving more industry limelight over the past few years. Three dry Chenin blanc wine styles are currently described by the wine industry as Fresh and Fruity (FF), Rich and Ripe unwooded (RR-unwooded) and, Rich and Ripe wooded (RR-wooded). According to the South African wine industry, however, consumers seem to be somewhat confused by these various Chenin blanc wine styles, which have not yet been clearly defined and classified. During this study we investigated the following perspectives of this wine style classification confusion: Currently, no specified sensory method is being used to differentiate between wine styles of a single wine cultivar, such as Chenin blanc. The sorting method can be used as a more cost and time effective classification and profiling method than general quantitative descriptive analysis (QDA). It was therefore investigated whether both uninstructed and instructed sorting, with consumers and wine experts, can be used to classify and describe the Chenin blanc wine styles similarly to QDA. The increase in young wine consumers, Generation Y, introduces new wine marketing opportunities for the wine industry which need to be investigated. Young consumers are not aware of the various Chenin blanc wine styles, which may influence their wine preferences. The influence of wine style knowledge on these consumers’ wine style preferences were investigated during blind and wine style informed preference test. Any segmentation within this Generation Y group was also investigated with regards to their Chenin blanc wine style preferences and/or exploratory data. The following scientific and industrial findings were made: QDA was successfully substituted by instructed and uninstructed sorting tasks. Although the sorting tasks easily differentiated between wooded and unwooded wines, QDA differentiated more successfully between the unwooded wines. Wine tasting experience did not significantly influence the sorting results of the consumers versus the wine experts, but more experienced panellists consistently used fewer descriptors than untrained consumers. All panellists sorted products slightly better when they were provided with wine style sorting instructions. However, there were no significant differences between the instructed and uninstructed sorting task results, i.e. a wine style descriptor list did not improve panellists’ abilities to describe their sorted wine groups. South African Chenin blanc wines can definitely be divided into wooded and unwooded wine styles, i.e. two wine style groups, but the unwooded Chenin blanc wine spectrum formed a wine-style-continuum. This finding is apparent from both the sorting and QDA methods. The unwooded continuum wines can further be differentiated from one another with the use of a fresh-to-mature scale and/or a light-to-full body scale during QDA. Generation Y wine consumers preferred all the Chenin blanc wine styles equally and moderately during the blind tasting, but their knowledge of the wine style concepts significantly increased their preferences for the wines during the informed wine style tasting. The cognitive influence of wine style knowledge is therefore powerful in terms of influencing a consumer’s wine preferences. Other interesting correlations were also made between Generation Y consumers’ wine style preferences and their exploratory data.
AFRIKAANSE OPSOMMING: Suid-Afrikaanse Chenin blanc wyn word gekarakteriseer deur styl diversiteit en is die afgelope paar jaar meer in die kollig. Drie droë Chenin blanc wynstyle word tans deur die wynbedryf beskryf as: Vars en Vrugtig, Ryk en Ryp ongehout en, Ryk en Ryp gehout. Volgens die Suid- Afrikaanse wynbedryf is daar heelwat verwarring is tussen hierdie Chenin blanc wynstyle weens die feit dat hierdie wynstyle nog nie duidelik gedefinieer en geklassifiseer is nie. Tydens die huidige studie het ons die volgende perspektiewe van hierdie wynstyl-verwarring ondersoek: Huidiglik word daar geen gespesifiseerde sensoriese metode gebruik om te onderskei tussen verskillende wynstyle van ’n enkele wyn kultivar, soos Chenin blanc, nie. Die sorteringsmetode kan gebruik word, instede van kwantitatiewe beskrywende analise, as ’n meer koste- en tyd-effektiewe produk klassifikasie en profileringsmetode. DIt was dus ondersoek of beide geïnstrukteerde en ongeïnstrukteerde sorteringstake, met verbruikers en wynkundiges, gebruik kan word om die verskeie Chenin blanc wynstyle kan profileer en klassifiseer soortgelyk soos kwantitatiewe beskrywende analise. Die toename in jong verbruikers, Generasie Y, skep nuwe wynbemarkingsgeleenthede wat ondersoek moet word. Jong verbruikers se onbewustheid van die verskeidenheid Chenin blanc wynstyle mag hulle voorkeure vir hierdie wyne beïnvloed. Die invloed van wynstyl kennis op hierdie jong verbruikers se wynstyl voorkeure was ook ondersoek gedurende ’n blinde en ’n wynstyl-ingeligte voorkeur toets. Enige segmentasie binne hierdie Generasie Y verbruikersgroep was ook ondersoek in verband met hul Chenin blanc wynstyl voorkeure en/of verkennende data. Die volgende wetenskaplike en industriële bevindings is gemaak: Kwantitatiewe beskrywende analise kan suksesvol vervang word deur beide geïnstrukteerde en ongeïnstrukteerde sorteringsmetodes. Alhoewel die sorteringsmetodes maklik gebruik kon word om te onderskei tussen gehoute en ongehoute wyne, kan kwantitatiewe beskrywende analise fyner onderskeid tref tussen die individuele ongehoute wyne. Die wynproe-ervaringsvlak het geen invloed op die sorteringsresultate gehad nie, maar meer ervare paneellede het konsekwent gebruik gemaak van minder beskrywende terme as onopgeleide verbruikers wat baie meer en verskillende soorte terme gebruik het. Beide panele het effens beter gesorteer wanneer hulle spesifieke wynstyl sorteringsinstruksies ontvang het. Daar was egter geen beduidende verskille tussen die geïnstrukteerde en ongeïnstrukteerde sorteringsresultate nie, wat daarop dui dat sorteringsinstruksies en ’n lys van wynstyl beskrywings nie die paneellede se wyse van sortering verander het nie. Suid-Afrikaanse Chenin blanc wyne kan definitief verdeel word in gehoute en ongehoute wynstyle, d.w.s twee wynstyl groepe, maar die ongehoute Chenin blanc wyn spektrum vorm ’n wynstyl-kontinuum. Laasgenoemde is bevind tydens beide die sorteringstake asook kwantitatiewe beskrywende analise. Die ongehoute kontinuum wyne kan verder van mekaar onderskei word met behulp van ‘n vars-tot-volryp en/of ‘n ligte-tot-volmond skaal tydens kwantitatiewe beskrywende analise. Alle jong wyn verbruikers het ewe veel van al die wynstyle gehou tydens die blinde wynstyl voorkeur toets, maar tydens die wynstyl-ingeligte voorkeur toets het hulle voorkeure vir al die wynstyle drasties verbeter. Die kognitiewe invloed van Chenin blanc wynstyl kennis kan dus lei tot hoër voorkeure vir die wynstyle. Ander interessante korrelasies is ook bevind tussen hierdie Generasie Y wyn verbruikersgroep se wynstyl voorkeure en hul verkennende data.

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Louw, Leanie. "Sensory analysis of brandy: the application of rapid profiling methodologies." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86483.

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Thesis (PhD)--Stellenbosch University, 2014.
ENGLISH ABSTRACT: Brandy has a high alcohol content of at least 36% alcohol by volume and a complex volatile chemical structure. Due to this, the sensory evaluation of brandy is challenging to execute and must be carefully managed to avoid panellists’ sensory and mental fatigue. Although rapid sensory profiling methods, such as projective mapping (PM), are commonly used for fast moving consumer goods, it was unclear whether these methods could accommodate the difficulties associated with brandy evaluation. The primary objective of this study was to validate PM, also called Napping®, as a reliable tool for brandy evaluation. Two variations of PM were tested: global napping (GN) where products are evaluated based on overall sensory perception, and partial napping (PN) where the product perception is broken down in to separate sensory modalities, in this case appearance, aroma and in-mouth sensations. Several practical aspects of PM were investigated in order to optimise the method for brandy evaluation and to gain understanding into practical methodological aspects that have not been fully understood at the onset of this study. The results showed that both GN and PN delivered reliable results, but that PN was more reproducible and better suited to larger sample sets (10 products). The concept of in-mouth sensations was found to be ineffective in extracting useful information on mouthfeel differences in the product set and that retronasal flavour should be separated from basic tastes and mouthfeel. A verbal instruction to the panellists was sufficient to obtain reliable information on mouthfeel differences; it was not necessary to use black glasses or nose-clips to eliminate the influence of appearance and flavour perception. In response to the insufficient reproducibility of GN, the sorting method was tested and validated as a suitable screening method that delivered reliable product maps of larger sample sets (10 products) in one replication, compared to GN which has to be replicated several times. A recent hypothesis states that the elongated horizontal dimension of a rectangular PM tasting sheet could be used to elicit more prominent product differences, while tasting sheets without an elongated axis, such as circles or squares, could be used to bring forth more subtle differences. This hypothesis was challenged by testing rectangular, square and round tasting sheet shapes. Although differences were observed between the shapes in terms of product configuration and panellist performance, the practical value of using different tasting sheet shapes to obtain specific information could not be established. The impact of high alcohol content and product complexity on panellist performance in PM was tested and it was concluded that product complexity did influence the panellists’ performance, particularly for high alcohol products. It was also found that prior knowledge of a products’ high alcohol content influenced the panellists’ descriptive language to include more alcohol-related terms. A new panellist performance measure was developed, namely the Relative Performance Index (RPI). This measure can be used to monitor trained panellists’ performance in the PM task more effectively to thereby ensure reliable results. The outcomes of this study extended the brandy sensory evaluation toolbox. Practical measures were identified that can be used to overcome the challenges associated with the sensory evaluation of complex high alcohol products.
AFRIKAANSE OPSOMMING: Met ‘n alkohol inhoud van mintens 36% alkohol per volume en ‘n komplekse vlugtige chemise samestelling is brandewyn ‘n uitdagende produk om sensories te evalueer. Maatreëls moet in plek gestel word om te verhoed dat sensoriese paneellede nie uitgeput raak nie om sodoende betroubare resultate te verseker. Hoewel vinnige sensoriese toetsmetodes, soos projeksiekartering (PM) en sortering, gereeld gebruik word vir die evaluasie van vining bewegende verbruikersgoedere was dit weens die voorafgenoemde redes onduidelik of die metodes geskik sou wees vir brandewynevaluasie. Die oorhoofse doelwit van hierdie projek was om PM, ook genoem Napping®, te valideer as ‘n geskikte metode vir die sensoriese evaluering van brandewyn. Twee variasies van PM is ondersoek: oorhoofse kartering (GN) waar die produkte op grond van ‘n algehele sensoriese waarneming evalueer word, en gedeeltelike kartering (PN), waar die verskillende sensoriese waarnemingsmodaliteite afsonderlik gemeet word. In hierdie geval is voorkoms, aroma en algehele binne-mondse ervaring gemeet. Verskeie aspekte van GN en PN is ondersoek ten einde die metodes vir brandewynevaluasie te optimiseer asook lig te werp op praktiese metodologiese aspekte waaroor daar nog onsekerheid was by die aanvang van hierdie studie. Die resultate het getoon dat beide GN en PN betroubare inligting oor brandewyn kan oplewer, maar dat PN meer herhaalbaar en beter geskik is vir groter produkstelle (10 produkte). Dit is egter bevind dat die konsep van algehele binne-mondse waarneming nie doeltreffend was om mondgevoelverskille tussen produkte uit te lig nie. Smaak- en mondgevoelwaarnemings moet liefs onderskei word van binne-mondse geurwaarneming. Dis bevind dat dit voldoende is om hierdie onderskeid deur skriftelike instruksies tot die paneel te bewerkstelling en dat die gebruik van swart glase en neusknippies nie nodig was om betekenisvolle inligting oor mondgevoel te bekom nie. Na aanleiding van die swak herhaalbaarheid van GN, is sortering getoets en gevalideer as ‘n geskikte siftingsmetode wat betroubare produkkaarte van groot produkstelle (10 produkte) kan oplewer met slegs een evaluasie, teenoor GN waarvoor meer as een sessie benodig word. ‘n Onlangse hipotese stel dat die langer horisontale dimensie van reghoekige PM proekaarte gebruik kan word om meer prominente verskille tussen produkte uit te wys, terwyl proekaarte sonder verlengde asse, soos sirkels en vierkante, gebruik kan word om meer subtiele verskille uit te wys. Hierdie hipotese is bevraagteken deur reghoekige, vierkantige en ronde PM proekaarte teenoor mekaar te toets. Hoewel die resultate vanaf die verskillende proekaarte effens verskil het in terme van produk konfigurasie en die paneel se taakverrigting, kon die praktiese waarde van die gebruik van produkkaarte met verskillende vorms om spesifieke inligting te bekom nie bevestig word nie. Die impak van hoë alkohol en produkkompleksiteit op paneellede se PM taakverrigting is ondersoek. Dit is bevind dat produkkompleksiteit wel hul taakuitvoering beinvloed, en dat hierdie invloed groter is vir hoë alkohol produkte. Dit is ook gevind dat paneellede se beskrywende taalgebruik beïnvloed om meer alkoholverwante woorde in te sluit word indien hul kennis dra van ‘n produk se hoë alkohol inhoud. ‘n Nuwe vaardigheidsberaming vir die meet van paneellede se taakverrigting is ontwikkel, naamlik die Relatiewe Taakverrigtingsindeks (RTW). Dit kan gebruik word om paneellede se vaardigheid in PM meer doeltreffend te monitor en sodoende betroubare resultate te verseker. Die uitkomste van die studie het die poel beskikbare metodes vir die sensoriese evaluering van brandewyn suksesvol verbreed en praktiese maatreëls is geidentifiseer om die uitdagings van ‘n komplekse hoë alkohol produkte te oorkom.

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Wilker, Karl Lawrence. "Effect of oak aging treatments on the phenolic composition and sensory quality of Seyval blanc wines /." The Ohio State University, 1986. http://rave.ohiolink.edu/etdc/view?acc_num=osu148726802174669.

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Weightman, Jayne. "Characterization of Chenin Blanc wines produced by natural fermentation and skin contact : focus on application of rapid sensory profiling methods." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/96008.

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Thesis (MSc)--Stellenbosch University, 2014.
ENGLISH ABSTRACT: Producers of South African (SA) dry and semi-dry Chenin blanc table wines are currently experimenting with winemaking techniques to modulate the flavours of the predominantly fruity styles of this genre. An important stage during wine style development is sensory profiling paired with consumer acceptance testing, before wine is produced on industrial scale. With those aforementioned goals in mind, this study was conducted in partnership with two commercial SA wine cellars. The main focus of the study was an investigation into the treatment effects of two winemaking techniques, respectively grape skin contact and natural fermentation, on the sensory profiles of experimentally produced Chenin blanc wines. Results obtained with descriptive sensory analysis (DA) of the wines were compared to those obtained by two rapid sensory profiling methods, namely projective mapping (PM) and frequency of attribute citation (FC). A consumer preference study was also done on the wines. In order to understand the treatment effects better, the dominant non-Saccharomyces yeasts that were present during the natural fermentations were identified using polymerase chain reaction (PCR), while the major volatile chemical compounds were identified with chromatography and mass spectrometry. The sensory and chemical profiles of the naturally fermented wines were significantly different from those of the inoculated wines. PCR analysis identified some of the yeasts present during alcoholic fermentation. In comparison to the inoculated fermented wines, the naturally fermented wines were generally perceived to have more intense and riper tropical fruity aromas, with enhanced sweetness and reduced intensities of sourness, bitterness and astringency. The wines fermented on the skins (FoS) had lower ester and volatile thiol concentrations than the control wines (with no skin contact) and limited skin contact wines. Sensory attributes linked to the FoS wines included aromas of dried fruit, dried grass and a vegetative character, with an increased sour and bitter taste and astringent mouthfeel. In contrast, the wines that were produced with limited skin contact (12 hours) retained their tropical fruity aromas better than the FoS wines. Limited skin contact seemed to have had a less harsh effect on the taste and mouthfeel than the FoS wines. A consumer study was done to establish a Generation Y consumer group’s (18-35 years) preference for the different treated wines. Overall, the naturally fermented wines, which were described as having a strong tropical fruit character, were preferred. The FoS wines were generally disliked by the consumers. Results obtained from the three sensory analysis methods, respectively DA, PM and FC, were similar, thereby confirming the suitability of the rapid methods PM and FC, to extract qualitative information from the sensory profiling of white wine. The results of this study made a significant contribution towards validation of rapid sensory methods for wine evaluation, which are particularly valuable in the context of sustainability and technology transfer to research and industry alike. The knowledge gained on the chemical profiles of SA Chenin blanc is novel and this is one of the first reports on the volatile thiol content of SA Chenin blanc wine.
AFRIKAANSE OPSOMMING: Produsente van Suid-Afrikaanse (SA) droë en semi-droë Chenin blanc tafelwyne eksperimenteer tans met wynmaaktegnieke om die oorwegend vrugtige style van hierdie genre te varieer. ‘n Belangrike fase van wynstylontwikkeling is sensoriese profilering van die produkte met gepaardgaande verbruikersaanvaardingstoetse, voordat die wyne op industriële skaal geproduseer word. Met dié bogenoemde doelwitte in gedagte, was hierdie studie in vennootskap met twee kommersiële SA wynkelders gedoen. Die hooffokus van die studie was om die invloed van twee wynmaaktegnieke, onderskeidelik druifdopkontak en natuurlike fermentasie, op die sensoriese profiele van eksperimenteel geproduseerde Chenin blanc wyne te ondersoek. Resultate wat met beskrywende sensoriese analise (DA) van die wyne verkry is, is vergelyk met dié wat deur twee vinniger sensoriese profileringsmetodes metodes, naamlik projektiewe kartering (PM) en frekwensie van kenmerkaanhaling (FC) verkry is. 'n Verbruikervoorkeurstudie is ook op die wyne gedoen. Ten einde die behandelingseffekte beter te verstaan, is die dominante nie-Saccharomyces giste wat teenwoordig was tydens die natuurlike fermentasie geïdentifiseer met behulp van die polimerasekettingreaksie (PCR), terwyl die vernaamste vlugtige chemiese verbindings geïdentifiseer is met chromatografie en massaspektrometrie. Die sensoriese en chemiese profiele van die natuurlike gefermenteerde wyne was beduidend anders as dié van die geiinokuleerde wyne. PCR analise het sommige giste wat teenwoordig was tydens alkoholies fermentasie geïdentifiseer. In vergelyking met die geiinokuleerde wyne, het die natuurlik gefermenteerde wyne intenser en ryper tropiese vrugtige aromas getoon, met ‘n verhoogde perspesie van soetheid en laer intensiteite van suurheid, bitterheid en vrankheid. Die wyne wat berei is deur fermentasie op die druifdoppe (FoS) het laer konsentrasies van esters en vlugtige swawelverbinding gehad, as die kontrole wyne (geen dopkontak) en beperkte dopkontak wyne. Sensoriese eienskappe gekoppel aan die FoS wyne was geasssosieer met gedroogde vrugte, gedroogde gras en 'n vegetatiewe aroma, met gepaardgaande verhoogde suur en bitter smaakpersepsies en ‘n frank mondgevoel. In teenstelling, het die wyne wat geproduseer is met 'n beperkte dopkontak (12 uur) hul tropiese vrugtige aroma beter behou as die FoS wyne. Beperkte dopkontak het ook ‘n minder negatiewe uitwerking op die smaakpersepies van bitterheid en vrankheid gehad. ‘n Verbruikerstudie is gedoen om 'n groep jong Generasie Y verbruikers (18-35 jaar) se voorkeure vir die verskillende behandelings te bepaal. Oor die algemeen is die natuurlike gefermenteerde wyne, wat beskryf is met 'n sterk tropiese vrugtekarakter verkies, terwyl die groep nie van die FoS wyne gehou het nie. Resultate wat verkry is met drie sensoriese analise metodes, onderskeidelik DA, PM en FC, was soortgelyk en die geskiktheid van die vinniger metodes, PM en FC, om kwalitatiewe inligting van witwyn se sensoriese eienskappe te verkry, is bevestig. Die resultate verkry met hierdie studie maak ‘n beduidende bydrae tot die validering van vinniger sensoriese metodes vir wynevaluering, wat veral waardevol is in die konteks van volhoubaarheid en tegnologieoordrag na navorsing en die industrie. Die nuwe kennis wat in hierdie studie gegenereer is met die chemiese profilering van SA Chenin blanc wyn is baie waardevol en hierdie is een van die eerste narvorsingsprojekte oor die inhoud van vlugtige swawelverbings in SA Chenin blanc wyn.

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Malherbe, Sulette. "Investigation of the impact of commercial malolactic fermentation starter cultures on red wine aroma compounds, sensory properties and consumer preference." Thesis, Stellenbosch : University of Stellenbosch, 2011. http://hdl.handle.net/10019.1/6587.

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Thesis (PhD)--University of Stellenbosch, 2011.
ENGLISH ABSTRACT: Wine is the result of a variety of biochemical reactions and microbial interactions which contribute to the organoleptic properties of wine. Wine aroma and flavour encapsulate the sensory experience of wine and could ultimately determine wine quality and consequently influence consumer acceptance and preference of a product. A thorough understanding of potential factors influencing wine aroma and flavour is therefore needed in order to exploit such factors. The aim of this study was to evaluate the influence of commercial malolactic fermentation (MLF) starter cultures on wine composition, aroma and flavour and the potential impact on consumer preference of experimentally produced red wines. An analytical platform was established to capture the compositional changes induced by different MLF bacteria in experimentally produced red wines. A fast gas chromatography flame ionisation detection (GC-FID) method was developed to determine 39 wine volatile compounds in less than 15 minutes per sample. A 3-fold reduction in analysis time was achieved in comparison to a conventional GC-FID method (40 minutes). Analytes quantified comprise a large boiling point and polarity range which illustrates the robustness of the method. A method was also developed for the direct quantification of carbonyl compounds including diacetyl, acetoin, 2,3-pentanedione and certain aldehydes using headspace solid phase microextraction coupled to gas chromatography mass spectrometry (HS-SPME GC-MS). Both analytical methods showed satisfactory linearity, repeatability and limits of quantification. The contribution of four commercial Oenococcus oeni malolactic fermentation (MLF) starter cultures to the volatile composition, organic acid content and infrared spectral properties of experimentally produced South African red wines, showed significant strain-specific variations in the organic acid profiles, especially for the production of citric acid and lactic acid during MLF. Subsequently, concentrations of compounds related to citric acid metabolism, namely ethyl lactate, acetic acid, diacetyl and acetoin, were influenced accordingly. Bacterial metabolic activity increased the concentration of higher alcohols, fatty acids and esters, with a larger increase observed in ethyl esters compared to acetate esters. A strain-specific tendency to reduce total aldehyde concentrations was found at the completion of MLF, however, further investigation is needed to clarify this observation. Infrared spectral fingerprints were used to characterise the different bacteria and in addition, the prediction of MLF related compounds, diacetyl, acetoin and 2,3-pentanedione, from mid-infrared spectra was explored by partial least squares (PLS) models. Quantitative descriptive analysis (QDA) results depicted significant differences between wines fermented with different starter cultures, in terms of sensory attributes including buttery, fruity, nutty and yoghurt/buttermilk aroma as well as smoothness and mouth-feel attributes. Consumer preference testing results indicate that sensory differences imparted by different MLF bacteria could influence consumer-liking. Preference mapping revealed interesting relationships between sensory attributes and consumer-liking, that can be used for preliminary interpretative purposes. In conclusion, this study illustrated the potential impact of bacterial strains on wine aroma and flavour, resulting sensory properties and consumer preference through an integrative approach combining compositional, spectral, sensory and consumer data. The results presented in this study are of significance to the wine industry since they illustrate and reiterate the potential of different MLF starter cultures as an additional tool to contribute to wine aroma and flavour, and potentially influencing consumer preference and product liking.
AFRIKAANSE OPSOMMING: Wyn is die resultaat van ‘n verskeidenheid biochemiese reaksies en mikrobiologiese interaksies wat tot die organoleptiese eienskappe van die finale produk bydra. Wynaroma en geur vang die sensoriese ervaring van wyn vas en dit kan dus wynkwaliteit bepaal en gevolglik verbruikersaanvaarding asook voorkeur van ‘n produk beïnvloed. Die potensiële faktore wat wynaroma en geur kan beïnvloed moet dus vir hierdie rede deeglik bestudeer word ten einde sulke faktore ten volle te benut. Die doel van hierdie studie was om die invloed van kommersiële applemelksuurgisting (AMG) aanvangskulture op wynsamestelling, die gevolglike aroma en geur eienskappe en die potensiële impak op verbruikersvoorkeure te ondersoek. ‘n Analitiese platform is gevestig om die veranderings in samestelling veroorsaak deur verskillende AMG bakterieë in eksperimenteel bereide rooi wyne vas te vang. ‘n Vinnige gas chromatografiese vlam geïoniseerde deteksie (GC-FID) metode is ontwikkel vir die meting van 39 vlugtige komponente in minder as 15 minute per wynmonster. In vergelyking met ‘n konvensionele GC-FID metode (40 minute) is ’n 3-voudige vermindering in analise tyd behaal. Gekwantifiseerde komponente bestaan uit ‘n wye kookpunt- en polariteitsreeks wat die robustheid van die metode illustreer. ‘n Metode vir die direkte kwantifisering van karboniel komponente, insluitende diasetiel, asetoïen, 2,3-pentanedioon en verskeie aldehiede is ontwikkel met die gebruik van dampfase soliede fase mikroekstraksie gekoppel aan gas chromatografie massa spektrometrie (HS-SPME GC-MS). Albei analitiese metodes besit voldoende lineariteit, herhaalbaarheid en lae deteksie limiete. Die bydrae van vier kommersiële Oenococcus oeni AMG aanvangskulture tot die vlugtige samestelling, organiese suurinhoud en infrarooi spektrale eienskappe van Suid-Afrikaanse rooiwyn het beduidende ras spesifieke variasies in die organiese suur profiele, spesifiek vir die produksie van sitroensuur en melksuur gedurende AMG, vertoon. Gevolglik is die konsentrasies van komponente verwant aan sitroensuur metabolisme, naamlik etiellaktaat, asynsuur, diasetiel en asetoïen, dien ooreenkomstig beïnvloed. Bakteriese metaboliese aktiwiteit het ‘n toename tot gevolg gehad in die hoër alkohole, vetsure en algemene ester konsentrasies met ‘n groter toename in etiel-esters in vergelyking met asetaat-esters. ‘n Ras-spesifieke tendens om die totale aldehiedkonsentrasie te verminder na afloop van AMG, is waargeneem alhoewel verdere ondersoek in hierdie area nodig is. Infrarooi spektrale patrone is gebruik om verskillende bakterieë te karakteriseer asook om die voorspelling van spesifieke AMG verwante komponente soos diasetiel, asetoïen en 2,3-pentanedioon met die gebruik van mid-infrarooi spektrala parsiële kleinste kwadraat verskille (PLS) modelle te ondersoek. Kwantitiewe beskrywende sensoriese analise illustreer beduidende verskille tussen wyne wat gefermenteer is met verskillende aanvangskulture in terme van geure soos botteragtigheid, vrugtigheid, neutagtigheid, joghurt/karringmelkgeur, asook gladheid en mondgevoel eienskappe. Verbruikersvoorkeur resultate illustreer die groot invloed wat sensoriese verskille veroorsaak deur verskillende AMG bakterieë op verbruikersvoorkeure kan hê. Voorkeur kartering het interessante verhoudings tussen sensoriese eienskappe en verbruikersvoorkeure uitgelig. Hierdie studie illustreer die impak van bakteriese rasse op wynaroma en geur en verbruikersvoorkeure deur ‘n geïntegreerde benadering waarin samestellende, spektrale, sensoriese en verbruikersdata gekombineer is. Die resultate van hierdie studie is van belang vir die wynindustrie deurdat dit die potensiële bydrae van verskillende AMG kulture tot wynaroma en geur asook die potensiaal om verbruikersvoorkeure te beïnvloed, illustreer en beklemtoon.

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Almeida, Susana Cristina Aleixo de. "Emotional responses elicited by wine when pairing with high fat food." Master's thesis, ISA, 2017. http://hdl.handle.net/10400.5/14827.

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Mestrado em Viticultura e Enologia / Instituto Superior de Agronomia / Faculdade de Ciências. Universidade do Porto
This work was aimed at the evaluation of emotional responses elicited by wine before and after food consumption. The tastings were performed by one trained panel and by consumers, segmented by gender, Vinotype, 6-n-propylthiouracil (PROP) sensitivity and Saliva flow rate. Three commercial red wines with different sensory features were used: i) Grand Gold awarded wine from Alentejo (2013); ii) wine from altitude vineyards in Douro (2011), iii) classical European old wine (1999) from Bairrada. Wines were evaluated using a tasting sheet with emotional and conventional tasting descriptors before and after eating a typical Portuguese dish, whose distinctive feature was its high fat content. Overall, food did not change the global evaluation scores given to the wines but some of their characteristics were scored significantly different through the emotional tasting. The results of both panels demonstrated that the emotional responses were more correlated with the global evaluation of the wines than the classical sensory descriptors. Within the trained individuals, the main correlations with global evaluation were obtained with “Initial Impression”, “Expectation for the mouth” and “Impression in relation to odor”. In particular, the global evaluation for the Bairrada wine, could be predicted by a model including these three variables with a R2=0.73. With the untrained tasters, the correlation with global evaluation was only significant for the “Impression in relation to odor”. The average scores given to the three wines by both panels did not diverge, despite their different sensory attributes. Therefore, our work only reflected trends in wine preferences. The untrained panel preferred the Alentejo wine while the trained panel preferred the Douro wine, before the food ingestion. The correlations between the global evaluation and the other sensory descriptors for the Alentejo wine could not explain this preference. We speculate that the untrained panel scored the wines based on what they are used to drink, giving lower scores to the unfamiliar one. The trained panel demonstrated a higher correlation between emotional and sensory descriptors. In fact, the trained panel seemed to understand better the different range of qualities of the wines. After ingesting food, the preference changed only for the trained panel, showing preference to the Bairrada wine. Both panels agreed that the old Bairrada was the most complex and difficult wine to understand In conclusion, the emotional tasting sheet was easy to interpret by all segments of consumers, leading to open and fair answers because it appeals to individual personal feelings. This tasting approach appears to be promising in the rapid learning of the different wine styles. In the future, it would be interesting to evaluate the evolution of scores given to unfamiliar wines that would require time to be appreciated using appropriate foods. This way, the classical European wines, that are difficult to understand by consumers, would have a better chance to be correctly appreciated
N/A

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Lund, Cynthia M. "Investigation of New Zealand Sauvignon Blanc Wine Using Trained Sensory Panels." Thesis, University of Auckland, 2009. http://hdl.handle.net/2292/5168.

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ABSTRACT A core tool of sensory science is the use of trained descriptive panels. This research describes an investigation into the role of motivation in the performance of trained panels and the use of a trained panel to develop a better understanding of the perception of Sauvignon blanc wines. Substantial investment in time and money is directed towards ensuring trained panels perform optimally. Having selected a panel, the panel leader needs to ensure that panellists provide accurate, reliable data. Panellist motivation is also an important factor to consider. While performance psychology, education and sport science fields have researched motivation extensively, knowledge about panellist motivation within sensory science is limited. However, findings from existing research in these other areas - which suggest an important role for autonomy, competence and relatedness - can be applied to sensory panels in order to increase intrinsic motivation. The initial part of the research investigated the fundamental factors that affect and influence panellists’ motivation and participation. A survey (n=74) revealed that extra income and a general interest in food were the key drivers in inspiring people to become panellists, whilst enjoyment in being a panellist, interest in food, and extra income were key drivers for people to remain panellists. In a second survey, the intrinsic motivation of seven trained panels from four countries (n=108) was assessed. External panels were found to be more intrinsically motivated than internal panels. Experienced panellists had an increased perception of competence, which is a key factor for people to be intrinsically motivated. Understanding motivational frameworks currently used in other research fields and integrating them into existing panel training protocols may enhance and sustain panellists’ intrinsic motivation. A trained panel (n=14) was then used in the second part of the thesis to identify key flavours in Sauvignon blanc wines from Australia, France, New Zealand, Spain, South Africa and USA. Sixteen characteristics were identified and measured, including sweet sweaty passionfruit, capsicum, passionfruit skin/stalk, boxwood/cat’s urine, grassy, mineral/flinty, citrus, bourbon, apple lolly/candy, tropical, mint, fresh asparagus, canned asparagus, stonefruit, apple and snowpea. Principal component analysis was used to describe differences between regions and countries. Sauvignon blanc wines from Marlborough, New Zealand (NZ), were described by tropical and sweet sweaty passionfruit characteristics, while French and South African Sauvignon blanc wines were described as having flinty/mineral and bourbon-like flavors. Chemical analyses of these wines also showed that Marlborough, NZ wines had more methoxypyrazine and thiol compounds. A consumer study (n=109) showed that New Zealanders significantly prefer New Zealand style Sauvignon blanc. The final part of this research focused on using trained panellists to explore the interactions between volatile and non-volatile wine compounds and their effects on the aroma profile of New Zealand Sauvignon blanc wine. Four volatile aroma compounds that are important in New Zealand Sauvignon blanc wine were studied (isobutyl methoxypyrazine [MIBP], 3-mercaptohexanol [3MH], 3-mercaptohexanol acetate [3MHA], and ethyl decanoate). Each of these four aroma compounds were assessed in combination with three non-volatile polyphenolic compounds commonly found in Sauvignon blanc wine: catechin, caffeic acid and quercetin. Results showed each polyphenol had a unique effect when blended with a specific aroma compound, either suppressing, accentuating, or showing little effect on the perception of the aroma compounds. The perception of MIBP, 3MH, and ethyl decanoate were largely suppressed by the added polyphenols, with a few exceptions. The perception of 3MH was accentuated with the addition of caffeic acid, and the perception of 3MHA was accentuated with the addition of catechin. The interactive effects of aroma compounds with polyphenols likely reflect non-covalent associations in the wine solution that reduce the volatility of the aroma compounds. With an understanding of the interactive effects of volatile and non-volatile compounds in wine, winemakers might optimize the impact of selected volatile compounds by managing polyphenol levels, supporting their efforts to attain desirable wine aroma profiles.

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Prangova, Mimi. "Visualization of Sensory Perception Descriptions." Thesis, Linnéuniversitetet, Institutionen för datavetenskap, fysik och matematik, DFM, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-9130.

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Visualization of Sensory Perception Descriptors is a topic in the field of Information Visualization. It is concentrated on the research and development of methods for analyses of data related with human modalities description. One possibility for investigating sensory perception descriptors is analyzing a great number of wine tasting notes. This thesis is concerned with the visualization of wine tasting notes in order to aid linguistic analyses. It strives to find proper visualizations that will give a better insight into the language used in wine tasting notes. Two main processes are described in the following report. First it sets out the process of researching of different methods of information visualization that led to the final approach for representing the data. A number of concepts for text analyses are discussed and the most useful of them are developed further. Several approaches for text visualization and statistical information are combined to build a system for tasting notes analyses. The second part of the report describes the process of developing a prototype that implements the represented approaches and gives an opportunity for real testing and conclusions.

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Hanekom, Evette. "Chemical, sensory and consumer profiling of a selection of South African Chenin blanc wines produced from bush vines." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/71812.

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Thesis (MScFoodSc)--Stellenbosch University, 2012.
ENGLISH ABSTRACT: Twenty five commercial Chenin blanc wines produced solely from bush vine vineyards and including three vintages, three styles and five production areas, were sourced for this study. Descriptive sensory analysis (DSA) and chemical analyses including GC-FID (gas chromatography fitted with a flame ionisation detector) and FTMIR (Fourier transform mid-infrared) spectroscopy were employed to establish the sensory and chemical characteristics, whereas consumer tests were conducted to determine consumer perception and liking of bush vine Chenin blanc wines. DSA (a profiling technique) was also compared to the sorting task (a classification technique) with a description assignment to evaluate the sorting task’s ability to profile wines. According to the results of DSA, the wines separated into two groups. One group associated with sensory attributes which can be considered indicative of the Fresh and Fruity Chenin blanc style. The other group associated with sensory attributes which can be considered indicative of the Rich and Ripe style of Chenin blanc. No separation between the wooded and unwooded Rich and Ripe styles was apparent. According to the results of the chemical analyses, the wines also separated into two groups. This separation seemed to be caused by vintage and the chemical changes associated with ageing as the wines from the youngest vintage (2010) was strongly associated with high levels of esters and malic acid. The older wines were situated farthest away from these attributes indicating low concentrations. When comparing the results from the sorting task and DSA, it could be seen that similar wine style groupings formed, indicating that DSA can also be regarded as an effective tool when categorising wines. The differences in the positioning of some of the wines and attributes on the DSA multivariate plots and the sorting task plots could be attributed to the difference in panels used. The sorting task was conducted using an expert panel with persons illustrating significant technical knowledge of Chenin blanc wines. Experience, exposure and technical knowledge tend to establish a common language amongst wine experts which could have caused the expert panel to perceive some wines differently when comparing the results of the latter panel to that of the trained panel. DSA was found to remain the most effective method for establishing a comprehensive sensory profile. Consumer analyses showed that regular white wine drinkers prefer the unwooded styles (Fresh and Fruity and Rich and Ripe unwooded) of Chenin blanc more than the wooded style. It was also found that consumers with a higher level of objective wine knowledge tend to associate the terms ‘bush vine’ and ‘old bush vine’ with the Rich and Ripe style of Chenin blanc, whereas consumers with a lower level of objective wine knowledge associated ‘old bush vine’ with the Fresh and Fruity style. Since all the wines used in the consumer analysis were produced from old bush vines, it is evident that consumer education on the impact of bush vine training system and vine age on wine quality is needed. Better understanding of these principles could lead to elevated product appraisals and consumer satisfaction.
AFRIKAANSE OPSOMMING: Vyf en twintig kommersiële Chenin blanc wyne, uitsluitlik van bosstok wingerde geproduseer, is bekom vir hierdie studie. Die wyne het drie style, drie oesjare en vyf produksiestreke ingesluit. Beskrywende sensoriese analise (BSA) en chemiese analises, wat GC-FID (gas chromatografie gekoppel met vlam-ioniserende deteksie) en FTMIR (Fourier-transformering mid-infrarooi) spektroskopie insluit, is uitgevoer om onderskeidelik die sensoriese en chemiese eienskappe van die wyne te bepaal. Verbruikerstoetse is ook uitgevoer om verbruikerspersepsie en -voorkeure vir bosstok Chenin blanc wyne te bepaal. BSA (‘n profilerings tegniek) was ook vergelyk met ‘n sorterings taak (‘n klassifikasie tegniek) met ‘n beskrywings opdrag, primêr om die sorterings taak se vermoë om wyne te profileer te ondersoek. Volgens die resultate van BSA, het die wyne in twee groepe verdeel. Een groep het met die sensoriese eienskappe wat op ‘n Vars-en-Vrugtige-styl dui, geassosieër. Die ander groep het met sensoriese eienskappe geassosieër wat met die Volrond-styl verband hou. Geen verdeling tussen die gehoute en ongehoute wyne binne die Volrond-styl was sigbaar nie. Volgens die resultate van die chemiese analises, het die wyne ook in twee groepe verdeel. Die verdeling blyk asof dit veroorsaak is deur oesjaar en die chemiese veranderinge wat met wynveroudering gepaard gaan. Wyne van die jongste oesjaar (2010) het ‘n sterk verband met hoë vlakke van esters en appelsuur getoon. Die ouer wyne was verder weg van hierdie eienskappe geleë, wat op laer ester en appelsuur konsentrasies dui. Wanneer die meerveranderlike resultate van die sorterings taak (met en sonder die aanduiding van sensoriese eienskappe) en dit van BSA vergelyk word, kon soortgelyke groeperings gesien word. Dit is ‘n aanduiding dat BSA ook wyne effektief kan kategoriseer. Die verskil in posisionering van sommige wyne tussen die BSA en sorterings taak resultate, kan toegeskryf word aan die verskillende panele wat gebruik is om die tegnieke uit te voer. ‘n Deskundige paneel (wynkenners) is gebruik om die sortingstaak uit te voer. Ervaring, blootstelling en tegniese kennis is geneig om te lei tot die vestiging van ‘n gemeenskaplike taal onder wynkenners. Hierdie gemeenskaplike taal kan as rede aangevoer word vir die uiteenlopende analise van sommige wyne wanneer die resultate van die deskundige paneel met dié van die opgeleide paneel (in BSA gebruik) vergelyk word. Dit is gevind dat BSA, wanneer ‘n omvattende sensoriese profiel bepaal moet word, die mees effektiefste metode bly. Verbruikerstoetse het getoon dat gereelde witwyn-verbruikers die ongehoute Chenin blanc style (Vars-en-Vrugtig en ongehoute Volrond) bo die gehoute styl verkies. Dit is ook bepaal dat verbruikers met ‘n hoër vlak van objektiewe wynkennis neig om die terme ‘bosstok’ en ‘ou bosstok’ met die Volrond-styl van Chenin blanc te assosieer, terwyl verbruikers met ‘n laer vlak van objektiewe wynkennis die term ‘ou bosstok’ met die Vars-en-Vrugtige Chenin blanc styl assosieër. Aangesien al die wyne wat in die verbruikerstoetse ingesluit is van ou bosstok wingerde geproduseer is, is dit duidelik dat verbruikeropvoeding insake die effek van die gebruik van bosstokke en ou wingerdstokke op wynkwaliteit noodsaaklik is. ‘n Beter begrip van hierdie beginsels sal lei tot verhoogde produkwaardasie, asook ‘n toename in verbruikertevredenheid.

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Robbins, Lisa R. "The Effects of Hyperoxidation and Storage Temperatures on the Flavor Profile and Sensory Quality of Riesling Wine." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1511893070533362.

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Nell, Marissa. "Sensory characterisation of several red cultivar (Vitis vinifera L.) wines, using berry sugar accumulation as a physiological indicator and sequential harvest." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/96887.

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Thesis (MSc)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: The global wine industry has shifted to a more adopted ‘consumer-preference’ production. Modern wine consumers are more knowledgeable and cultivated in their understanding of wine quality, value and style. The quality of red wines mainly depends on grape composition, the wine making process and the ability of tasters to recognise sensory attributes. The harvest date/stage has an influence on the grape composition, thus making the decision on when to harvest an important factor in the production of quality wines or different wine styles. The traditional indicators used in the wine industry to determine time of harvest are more related to the perception of taste and mouthfeel and give little indication of the style of wine in terms of aromatic profile. A new physiological indicator using berry sugar accumulation for the purpose of sequential harvest is proposed to assist the winemaker in producing wines with possible different sensory profiles. This indicator can be used in association with the classical indicators of ripening to affect the diversity of wine styles from a single vineyard or a group of vineyards. The wines could thus have different potential aroma profiles, depending on when the grapes were harvested. The main aim of this study was to assess the effect of performing sequential harvest using a physiological indicator on red wine’s sensory composition. This was done to study the possible relation between harvest time (e.g. fruit composition evolution) and the wine styles/sensory attributes across the different harvest times, thereby possibly increasing the diversity of wine styles. A theoretical berry sugar loading concept was compiled and displays a phase of rapid sugar loading starting at véraison followed by a plateau phase. Depending on whether grapes were harvested in the beginning, mid or end of the plateau phase of fruit sugar accumulation the wines could have different potential aroma profiles. Three main stages: fresh fruit (FF), neutral (N) or pre ripe and mature fruit (MF) has been previously proposed using the sugar loading concept and in terms of harvesting dates. Cabernet Sauvignon and Merlot grapes form Eikendal Vineyards, Stellenbosch were used to make wines according to sequential harvest. Four harvest stages were considered, pre fresh fruit (Pre FF), fresh fruit (FF), mature fruit (MF) and over ripe (OR). The wines were tasted and analysed using two different sensory techniques. In both Merlot and Cabernet Sauvignon wines, the PreFF and OR stages could be more easily discriminated than the two harvest stages in-between, FF and MF. The results suggested that the wines made from the FF and MF stages could not be distinguished from each other in general when the attribute citation frequency method or sorting tasks were performed. However, a trend could be observed for both Cabernet Sauvignon and Merlot wines in terms of aroma attributes with attributes changing from green to ripe fruit during ripening using expert tasters. Relevant research should be engaged to refine sequential harvest in order to obtain more diverse wine styles from a single site or a group of vineyards.
AFRIKAANSE OPSOMMING: Die wêreldwye wynbedryf het ’n verskuiwing ondergaan na ’n verbruikersvoorkeurbenadering in produksie. Wynverbruikers is deesdae beter ingelig en meer ontwikkeld ten opsigte van hulle kennis van wyngehalte, wynstyl, asook die waarde van wyn. Die gehalte van rooiwyn hang hoofsaaklik af van die druifsamestelling, die wynmaakproses en die vermoë van proewers om sensoriese eienskappe te herken. Aangesien die oesdatum/-fase ’n invloed het op druifsamestelling, is die besluit oor wanneer daar geoes moet word ’n belangrike faktor in die vervaardiging van gehaltewyne of verskillende wynstyle. Die tradisionele aanwysers wat in die wynbedryf gebruik word om oestyd te bepaal, hou verband met die waarneming van smaak en mondgevoel en gee weinig aanduiding van die wynstyl op grond van die aromatiese profiel. ’n Nuwe fisiologiese aanwyser wat gebruik maak van suikerakkumulasie in die druiwekorrel in opeenvolgende oeste, het ten doel om die wynmaker te help om wyne met verskeie moontlike sensoriese profiele te vervaardig. Hierdie aanwyser kan saam met die klassieke aanwysers van rypwording gebruik word om ’n verskeidenheid wynstyle uit een wingerd of wingerdgroep te vervaardig. Die wyne kan dus potensieel oor verskillende aromatiese profiele beskik, afhangend van wanneer die druiwe geoes is. Die hoofdoel van die studie was om die invloed van opeenvolgende oes te toets deur ’n fisiologiese aanwyser op rooiwyn se sensoriese samestelling toe te pas. Dit word gedoen deur die moontlike verhouding tussen die oestyd (bv. ontwikkeling van vrugsamestelling) en die wynstyle of wyn se sensoriese kenmerke op verskillende oestye te bestudeer ten einde die verskeidenheid wynstyle potensieel te vermeerder. ’n Teoretiese konsep van druifsuikeropname is saamgestel wat dui op ’n fase van vinnige suikeropname wat by véraison begin, gevolg deur ’n plato-fase. Wyn kan oor verskillende moontlike aromatiese profiele beskik, afhangend daarvan of die druiwe aan die begin, middel of einde van die plato-fase van suikeropname geoes is. Drie hooffases is al voorheen voorgestel deur gebruik te maak van die konsep van suikeropname volgens oesdatum, te wete vars vrugte (VV) (“fresh fruit”, FF), neutraal (N) (“neutral”, N) of voor ryp (“pre ripe”), en ryp vrugte (RF) (“mature fruit”, MF). Cabernet Sauvignon- en Merlot-druiwe van Eikendal, Stellenbosch, se wingerde is gebruik om wyn volgens opeenvolgende oes te maak. Vier oesfases is oorweeg, te wete voor vars vrugte (VVV) (“pre fresh fruit”, Pre FF), vars vrugte (VV) (“fresh fruit”, FF), ryp vrugte (RV) (“mature fruit”, MF), en oorryp (OR) (“over ripe”, OR). Die wyn is geproe en geanaliseer deur gebruik te maak van twee verskille sensoriese tegnieke. In die geval van beide die Merlot- en Cabernet Sauvignon-wyn kon die VVV- en OR-fases makliker onderskei word as die twee tussenin-fases, VV en RV. Resultate dui daarop dat wyn wat van die VV- en RV-fases gemaak is, oor die algemeen nie van mekaar onderskei kan word wanneer die frekwensie van kenmerkaanhaling-metode en sorteringstaak uitgevoer word nie. ’n Tendens kon egter waargeneem word vir Cabernet Sauvignon- én Merlot-wyn ten opsigte van aromatiese kenmerke, deurdat kenmerke gedurende rypwording van groen na ryp vrugte verander het indien ekspertproewers gebruik is. Verdere navorsing moet gedoen word om opeenvolgende oes te verfyn ten einde ’n wyer verskeidenheid wynstyle van ’n enkele area of wingerdgroep te verkry.

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Basson, Shantelle. "Consumer acceptance of a selection of South African red wines : intrinsic, extrinsic and socio-demographic influences." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/20380.

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Thesis (MSc Food Sc)--Stellenbosch University, 2012.
ENGLISH ABSTRACT: In this study an industry-selected and diverse range of South African red wines were analysed for sensory and chemical attributes, as well as degree of liking using a target group of black South African consumers. Segments of consumers that differed in degree of liking were then tested for their response to intrinsic (sensory) and extrinsic (non-sensory) cues. The selection of wines included eighteen dry and natural sweet red wines, representing low-end inexpensive wines together with high-end, top quality wines. Sensory profiles for all samples were established using Quantitative descriptive analysis (QDA). The results revealed that cultivar specific dry red wines associated with a wide range of sensory descriptors such as woody, vegetative and fruity, while the sweet red wines associated with the fruity and sweet-associated attributes. Chemically there was a significant variation between wines regarding the alcohol and sugar content. Gas chromatography with flame ionisation detection (GC-FID) indicated the major volatile constituents present in the wine, i.e. esters, alcohols and fatty acids. When investigating the association between the chemical and sensory data, it was revealed that the red blends were driven by the presence of alcohols and esters, and sensory descriptors such as high roast oak, coffee and mixed spice, whereas the red cultivar wines were mostly driven by fatty acids and esters and the sensory descriptors, green bean and asparagus. The sweet red blends were closely associated with acids and the sensory descriptors sweet-associated and floral. Degree of liking of a subset of 18 wines was investigated based on the preferences of black consumers from the Western Cape area, South Africa. These consumers predominantly preferred the sweet red wines with high sugar content, in a blind tasting session. Purchase intent was also evaluated by viewing actual photographs of packaging formats of the respective wines and the results indicated that the consumers preferred the well-known cultivar wines with a perception of value and style. Cluster analysis was furthermore performed to ascertain whether these consumers differed in their degree of liking of the intrinsic character of the respective wines. Four different clusters of consumers were identified: 1) Consumers preferring both dry and sweet red wines equally, 2) Consumers who strongly favoured sweet red wines and moderately liked dry red wines, 3) Consumers who strongly favoured sweet red wines with little preference for dry red wines; and 4) Consumers preferring dry red wines. Consumers were also probed on their general opinions or perceptions on the extrinsic character of the wines, and thus factors that influence the purchasing process. It was found that black consumers who don‟t consume wine often, preferred wines that they are familiar with, while consumers that drink wine more frequently enjoy to broaden their horizons by experimenting with more expensive wine brands. Extrinsic or non-sensory cues such as alcohol content, label, vintage, price and cultivar were found to be the most important considered factors when purchasing red wines, while awards and type of closure were regarded as the least important. It was also found that the discerning consumers, who purchase high-end wines, took more of the latter aspects into consideration, whereas consumers who purchase low-end wines considered a limited number of the non-sensory cues.
AFRIKAANSE OPSOMMING: In hierdie studie is 'n diverse reeks industrie-geselekteerde, Suid-Afrikaanse rooiwyne geanaliseer vir hul sensoriese en chemiese eienskappe. Verbruikersvoorkeur van die wyne is getoets, asook tot watter mate verbruikersvoorkeure beïnvloed word deur intrinsieke (sensoriese) en ekstrinsieke (nie-sensoriese) faktore. Die reeks van agtien wyne het bestaan uit droë en soet rooi wyne, wat op hul beurt verder verdeel kan word in goedkoper, kwaliteit wyne en duurder, ultra-premium wyne. Die sensoriese profiel van al die wyne is bepaal deur beskrywende sensoriese analise. Resultate het getoon dat die kultivar-spesifieke droë rooiwyne geassosieer word met 'n wye reeks sensoriese eienskappe soos houtagtig, kruidagtig en vrugtig, terwyl die soet rooiwyne beskryf is as vrugtige en soet-geassosieerd. In terme van die chemiese analises was daar betekenisvolle verskille betreffende die alkohol- en suikerinhoud van die wyne. Gas chromatografie gekoppel met vlam-ioniserende deteksie (GC-FID) het die mees vlugtige verbindings teenwoordig in die wyn aangedui, naamlik esters, alkohole en vetsure. Met die korrelasie van die chemiese en sensoriese data is gevind dat die droë versnitwyne gedryf word deur die teenwoordigheid van alkohole en esters, asook sensoriese eienskappe soos gehout, koffie, en gemengde spesery, terwyl die kultivar-spesieke wyne weer meestal gedryf word deur vetsure en esters en sensoriese eienskappe soos groenboontjie en aspersie. Die soet rooiwyne het chemies geassosieer met sure en sensoriese terme soos soet-geassosieerd en blomagtig. Die aanvaarbaarheid van 'n kleiner groepering wyne is bepaal deur gebruik te maak van swart verbruikers in die Wes-Kaap area, Suid-Afrika. Die verbruikers het in 'n blinde proesessie onderskeie wyne se wynverpakking besigtig en aangedui of hulle die wyne sou koop. Hierdie resultate het getoon dat die verbruikers bekende kultivarwyne verkies wat 'n persepsie van waarde en styl geïllustreer het. Segmentasie tegnieke is op die data uitgevoer ten einde te bepaal of verbruikers in groepe verdeel kan word, wat betref hul voorkeur van die sensoriese of intrinsieke eienskappe van die wyne. Vier verskillende groepe is geïdentifiseer, nl. verbruikers wat 1) droë en soet rooiwyne ewe veel verkies; 2) soet rooiwyne en tot 'n mate ook droë rooiwyne verkies; 3) soet rooiwyne en tot 'n mindere mate droë rooiwyne verkies; en laastens 4) slegs droë rooiwyne verkies. Verbruikers se algemene opinies en persepsies betreffende die ekstrinsieke eienskappe van die wyne is ook ondersoek, met ander woorde faktore wat die aankoop van wyne beïnvloed. Daar is gevind dat swart verbruikers wat nie gereeld wyn drink, bekende handelsmerke verkies, terwyl verbruikers wat gereeld wyn drink, daarvan hou om hul horisonne te verbreed en te eksperimenteer met 'n verskeidenheid handelsmerke. Ekstrinsieke of nie-sensoriese aspekte soos, alkohol-inhoud, etiket, oesjaar, prys en kultivar is die belangrikste faktore wat in ag geneem word wanneer rooiwyne gekoop word, terwyl wyntoekennings en die feit dat die wyn met kurke gebotteleer word, nie as belangrik beskou word nie. Daar is ook gevind dat die meer ingeligte verbruiker, wat hoë kwaliteit wyne koop, meer van die bogenoemde aspekte in ag neem tydens die aankoopproses, terwyl die verbruiker wat meer geneig is om goedkoper wyne te koop, slegs 'n paar ekstrinsieke faktore in ag neem.

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Correia, Carlos André Silva Henriques Martins. "Efeitos da poda manual e mecânica e da aplicação de diferentes correctivos orgânicos ao solo na composição química e análise sensorial de uvas e vinhos da casta Syrah nas regiões do Tejo e de Lisboa." Master's thesis, ISA, 2014. http://hdl.handle.net/10400.5/6874.

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Mestrado em Viticultura e Enologia - Instituto Superior de Agronomia / Faculdade de Ciências. Universidade do Porto
With the aim of studying the mechanization of vine pruning while still maintaining plant vigor and fertility of the soil, this study has tested the use of different types of fertilization in mechanical and manual pruning, in two different estates. The vinification of the grapes took place in the cellar of the Instituto Superior de Agronomia where, after natural clarification and stabilization the wines were bottled and subsequently analyzed. The analyzes were made on each of the different samples and consisted in the following parameters: Alcohol, Total Dry Extract, Total Acidity, Total Polyphenols, Total Anthocyanins, Color Intensity, Color tone, as well as the levels of Iron, Potassium, Calcium and Copper. In terms of results, the wines showed very similar parameters with small changes in values, but when subjected to a statistical analysis the results revealed not statistically significant, with the exception of Color tone and Potassium, although with very close values as well. With regard to sensory analysis it was observed a consistency in terms of results with the chemical analyzes, and it was also not evident a standard differentiator between the samples, confirmed by the variance analysis performed.

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Hughson, Angus. "Cork and talk the cognitive and perceptual bases of wine expertise /." Connect to full text, 2003. http://hdl.handle.net/2123/490.

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Thesis (Ph. D.)--University of Sydney, 2003.
Title from title screen (viewed Apr. 24, 2008). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Dept. of Psychology, Faculty of Science. Includes bibliography. Also available in print form.

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Romano, Mylena. "The influence of the organic label on the sensory profile and liking of wines. Is our perception and appreciation biased?" Master's thesis, ISA, 2019. http://hdl.handle.net/10400.5/19583.

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Vinifera Euromaster European Master in Viticulture and Oenology - Instituto Superior de Agronomia / EMaVE
Aiming to assess the influence of the organic mode of production on the acceptance and sensory profile of wines, consumers responded to a preliminary online survey to obtain information on willingness to pay and acceptance of unfamiliar flavours in organic wines. A knowledgeable and trained panel characterized several organic and conventional wines by free descriptive sensory analysis and provided their degree of liking, familiarity and willingness to pay (WTP). A total of 8 wines were tasted during 3 tasting sessions accompanied by 4 wines used as distractors. The information given to tasters was different in each session: (i) all wines were told to be conventional; (ii) all wines were told to be organic, and (iii) tasters were asked to guess the mode of production. The online survey showed the positive consumer opinion regarding organic wines for their environmental aspects reflected in higher WTP. Respondents were willing to accept flavour differences from conventional wines but leniency regarding any flaw was not supported. Tasters showed increasing liking scores and WTP in the organic labeled session. The liking scores grew 76.5% and the WTP, 98.7% when the tasters thought the wines were organic. The sensory profile of the wines varied according to the information, revealing an increased utilization of positive fruity and floral flavours. However, these observations were contradicted when tasters had to guess the production’s mode. Then, organic wines were linked to the eventual presence of negative flavours like animal and earthy while flawless wines were considered more likely to be conventional. Moreover, the emotional response “Unpleasant” was mostly used in the “guess” session and worked as a cue to define the mode of production. Finally, the organic label exerted a clear halo effect on wine appreciation, even when wines were evidently tainted and recognized as unpleasant by a knowledgeable tasting panel
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Ceciliani, Francesco. "Taster responses to acidity in white wines." Master's thesis, ISA-UL, 2017. http://hdl.handle.net/10400.5/13344.

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Mestrado Vinifera Euromaster - Instituto Superior de Agronomia - UL / Universitá degli Studi di Udine
The aim of this study was to evaluate the responses of a panel of tasters trained to acidity in white wines. The training of tastes and sensations of the mouth was performed in relation to the acidity, sweetness, bitterness and astringency. Next, the tasters were segmented according to vinotype, sensitivity to PROP (6-n-propylthiouracil) and saliva flow. This panel was used to determine the detection and recognition thresholds of tartaric, malic and lactic acids in white wine with 4.2 g / L of total acidity. The detection and recognition thresholds were 1.05 g/L and 1.32 g/L for tartaric acid, 0.85 g/L and 1.06 g/L for malic acid and 1.12 g/L and 1.30 g/L for lactic acid, respectively. These acids were added to an Arinto wine at concentrations 1.5 times higher than the recognition threshold, obtaining responses regarding the flavor effect considering intensity, persistence, salinity and appreciation. There were no differences (p<0.05) in relation to the first 3 parameters, while the appreciation was higher in relation to lactic and malic acids. The statistical treatment of the responses according to the segmentation revealed relationships (p<0.05) between saliva flow and sensitivity to PROP, and between saliva flow and the tartaric acid recognition threshold. The acidity appreciation was higher in men than in women. The results obtained can be used by the wine industry in the sense of adapting the white wines to the preference of the consumers, taking into account the recent trend towards the consumption of cold climate wines.
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Pardal, Rafaela Alexandra Cerqueira. "Physicochemical and sensory analysis of Syrah wines from vineyards mechanically pruned treated with different organic amendments." Master's thesis, ISA/UL, 2015. http://hdl.handle.net/10400.5/10922.

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Mestrado em Viticultura e Enologia - Instituto Superior de Agronomia / Faculdade de Ciências. Universidade do Porto
In order to study the effect of mechanical pruning and the addition of organic amendments to the vineyard in Syrah wine quality, three vineyards from different viticultural areas were tested – Quinta do Côro (Tejo), Quinta do Gradil (Lisboa) and Herdade de Rio Frio (Setúbal). In order to evaluate the influence of the treatments applied the wines were subjected to a physicochemical analysis as well as chromatic characteristics determination, total nitrogen content, mineral and heavy metals and other elements analysis and the tasting panel performed sensory analysis to determine if the differences were perceived. The results show that mechanical pruning led to wines with lower alcohol content, color intensity, total anthocyanin content as well as less tannin power and inferior tannin content. This type of pruning technique also led to lesser accumulation of minerals and lower levels of some heavy metals. In the sensory analysis, the wines from mechanically pruned vines were less appreciated by the tasters receiving worse scores, including lower global appreciation marks. The organic amendment that led to lower overall results in the studied parameters was sewage sludge, it reduced alcoholic content and color intensity as well as total anthocyanin content while grime and the control plots led to better results

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Van, Eeden Petrus Rabe. "Chemical, sensory and consumer analysis of cork taint in South African wines." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/2092.

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Thesis (MSc Food Sc (Food Science))--University of Stellenbosch, 2009.
This study focused on a serious quality-related problem in the global wine industry, including the South African Wine Industry, namely cork taint in wine. Annually, large financial losses are incurred by cork suppliers and wine producers, as a result of cork-tainted wine. Although contaminated new unused corks are frequently implicated as the origin of this taint, contaminated cellar equipment and water can also be the source of the problem. An explorative investigation into the incidence of cork taint in South African wines showed that 3.8% of the 133 wines tested, contained 2,4,6-trichloroanisole (TCA) concentrations of 3.5 ng/L and higher, as determined by gas chromatography coupled with electron capture detection (GC-ECD). TCA concentrations higher than 1 ng/L were found in 18% of the wines tested. All affected wines were sealed with solid or agglomerate cork stoppers. These wines were sourced from various wineries in the Western Cape region, South Africa and were of different cultivars. None of the wines sealed with synthetic closures had any detectable TCA, 2,4,6-tribromoanisole (TBA) or pentachloroanisole (PCA) levels and only very low 2,3,4,6- tetrachloroanisole (TeCA) levels (1 ng/L or less). Another group of 28 wines that were rejected by the official South African wine regulatory body on the basis of the presence of mouldy taint during wine certification, was also included in this study. GC-ECD analysis showed that 30% of the wines in this group contained TCA at concentrations of 3.5 ng/L and higher. These results pointed to a relative high incidence of TCA in the wines investigated, especially those sealed with cork stoppers. Although no general conclusions should be made on the incidence of cork taint in the wider wine industry based on the results found within this explorative investigation, these findings confirmed the presence of cork taint in South African wines. Detection threshold values were determined for TCA, TeCA, TBA and PCA in three wine cultivars using the standard ASTM method. Results indicate that factors relating to the wine cultivar seemed to affect threshold values considerably. Our research proposes a detection range rather than an average detection threshold. Detection ranges established for TCA, TeCA, TBA and PCA in Chenin blanc, Pinotage and Shiraz coincide with reported values in literature. This result can be regarded as a valuable expansion of the existing knowledge of detection threshold values. Descriptive sensory analysis indicated significant (P 0.05) changes in the aroma profile of Chenin blanc, Pinotage and Shiraz after TCA, TeCA, TBA or PCA was added to the respective base wines that contained no detectable levels of the haloanisoles. The mouldy taint induced by these haloanisoles were described as mouldy, mouldy-chemical, mouldychlorine, as well as mouldy-acidic. In Chenin blanc, additions of TCA, in the concentration range 1 to 17 ng/L, resulted in a marked increase in the mouldy aroma and was accompanied by an immediate decrease in fruitiness. This change was already evident at added TCA concentrations of 1 ng/L. Similar trends were observed in Pinotage, while the addition of low levels of TCA to Shiraz (2 ng/L) resulted in a significant (P 0.05) decrease in the herbaceous character of the wine. The aroma changes observed were prominent enough to render the wine totally unacceptable in comparison to its original character. Consumers’ degree of liking did not seem to be affected by very low concentration levels of TCA in Chenin blanc, Pinotage or Shiraz, but rejection increased as the concentration increased beyond detection threshold level. A slight gender effect was also noticed. Female consumers appeared to be more sensitive to increasing levels of TCA, whereas male consumers did not respond as negatively to higher concentration levels of TCA. This study makes an important contribution towards understanding the sensory impact of especially TCA contamination in wine, through the establishment of concentration ranges at which these compounds exert a noticeable detrimental effect on the aroma profile of wine. Additional insight into cork taint in wine is provided by the consumer preference studies, where the effects of the taint on the product acceptance by consumers are demonstrated. The development of a modus operandi to ensure that sensory panels provide reliable data, can be regarded as an important contribution to wine-related research. This study is one of the first where advanced sensometric techniques were applied in sensory studies on cork tainted wines.

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Nygren, Tobias. "Sensory evaluation and consumer preference of wine and food combinations : influences of tasting techniques /." Örebro : Örebro universitetsbibliotek, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-56.

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Nguyen, Dang-Dung. "The effects of micro-oxygenation on the evolution of red wine composition and sensory properties." Thesis, University of Auckland, 2011. http://hdl.handle.net/2292/6811.

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Micro-oxygenation (MOX) is a technique that continuously delivers a small metered amount of oxygen into a wine by means of micro-bubbling using a porous micro-diffuser. MOX is considered an effective oxygen management tool for winemakers to produce particular wines in a consistent style. While several beneficial effects of MOX on wine quality have been well examined in scientific research, information regarding the influence of MOX on the reductive sulfur containing off-odours, sulfur containing substances mainly produce unpleasant smells which impart organoleptic defects in wine, the well-known as rubbery or 'reduced' character, is very limited. Of note is that the term 'reductive' here refers to sulfur containing volatiles with detrimental effects on wine quality, to distinguish them with compounds responsible for characteristic varietal aromas. An analytical method, using headspace-microextraction coupled with Gas Chromatography-Mass Spectrometry, was successfully developed and validated for the separation and quantification of up to fourteen reductive 'light' and 'heavy' sulfur containing volatiles. The effects of MOX were examined using different oxygen dosage rates before and after malolactic fermentation (MLF) on a Cabernet Sauvignon and a BORDEAUX blend, respectively, in replicated trials using 300 L stainless steel tanks and high density polyethylene tanks (Flextanks). A commercial scale MOX trial on an Australian Shiraz after MLF was also monitored. The analysis focused upon the evolution of the chemical composition, especially the reductive sulfur compounds. Effects on the wine post MLF at the end of the MOX treatments in terms of the perceived sensory characteristics have also been investigated. Limited oxygen exposure stimulated wine colour development, with positive effects still observed when spontaneous MLF occurred during the MOX operation. A significant influence of oxygen on tannins was only seen in the Australian Shiraz with prolonged oxygenation. MOX had fairly limited effects on individual polyphenols, except for the highly oxidisable flavan-3-ol epicatechin and the monomeric anthocyanins. Oxygenation did not affect the desirable varietal thiol 3-mercaptohexanol (3-MH), but resulted in a lowering in the concentrations of most reductive sulfur compounds. These observations were reflected in the sensory characteristics of the finished wines. The research provides insights into the effects of MOX on the reductive sulfur compounds in terms of both quantitative and sensory perspectives, alongside the effect upon other wine constituents including the polyphenols. The results indicated that the chemical mechanism leading to a decrease in the off-odour methanethiol is more likely to be linked with oxidised wine polyphenols rather than from a direct oxidation to a disulfide. Increase in the content of dimethyl sulfide may come about from chemical transformations occuring during wine storage.

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Coste, Amaury. "Development of a new wine tasting method based on emotional responses." Master's thesis, ISA-UL, 2015. http://hdl.handle.net/10400.5/12215.

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Mestrado Vinifera Euromaster - Instituto Superior de Agronomia - UL
Conventional sensory analysis uses a technical language to define and quantify visual, aromatic and mouth-‐feel perceptions, while emotion based methods aim at qualifying the impressions or expectations these perceptions may trigger. The objectives this study were to (i) develop a wine tasting sheet including emotional responses and conventional sensory attributes; (ii) establish a list of emotions described by consumers after tasting red wine. A previous emotion based tasting sheet was improved through several Focus Group sessions. An Optimized Quantitative Descriptive Analysis (OQDA) was then run to assess 8 sensory descriptors of the emotional tasting sheet. Finally, 5 red wines were evaluated in a Final Consumer Tasting (FCT) of 103 consumers with the improved emotional tasting sheet and a Check-‐All-‐That-‐Apply questionnaire of 25 emotional adjectives. The main discriminating attributes were “Complexity” (Odor), “Astringency” (Taste) and “Duration of the fragrance of the wine” in the trained panel (OQDA) and “Color”, “Initial impression” (Odor) and “Expectation for the mouth” for the untrained tasters in the FCT. In particular, a classic European style red wine, was less liked in the FCT, though it received high scores in the OQDA and regarded as the most “surprising” in the CATA. This result is promising because it showed that emotional responses may enable an easier recognition of this wine style by consumers. Overall, the emotional method developed in this work proposes to evaluate wines in a way that is more accessible to the consumer than traditional sensory analysis

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Ngqumba, Zama. "Effect of Torulaspora delbrueckii and Saccharomyces cerevisiae yeasts on the phenolic content and sensory attributes of Chenin Blanc wines." Thesis, Cape Peninsula University of Technology, 2016. http://hdl.handle.net/20.500.11838/2333.

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Thesis (MTech (Chemistry))--Cape Peninsula University of Technology, 2016.
Wines contain a number of phenolic compounds, belonging to non-flavonoid and flavonoid complexes. Phenolic compounds in wine are responsible for wine colour, astringency, and bitterness. Saccharomyces cerevisiae yeast is normally used in winemaking but it has been proved to decrease the phenolic content in wines. Current research on the use of non-Saccharomyces yeast in winemaking has produced better quality wines than S. cerevisiae yeast therefore improving the sensory profile of wine. This study evaluated effect of Torulaspora delbrueckii yeast on the phenolic content of experimental wines derived from Chenin blanc grapes. A reversed phase high-performance liquid chromatographic (RP-HPLC) method was used for the identification and quantitation of the phenolic compounds. The difference test method was used to determine the sensory attributes of wines. The data was subjected to analysis of variance to compare treatment differences between the wines and principal component analysis to establish possible correlation between the data sets. Furthermore, a gas chromatographic-flame ionization detection method (GC-FID) was used for the quantification of volatile compounds in the wines. In this work, wines made with T. delbrueckii strain M2/1 had high concentration of (+)-catechin, caffeic acid, ferulic acid and p-coumaric acid in all studied vintages. Wines made with VIN13 had higher concentrations of flavan-3-ols, compared to wines made with M2/1 and 654. In sensory evaluation, M2/1 wines were prominent in astringency and complexity. Yeast strain M2/1, also attributed to body and complexity of the wine. However, in this study no correlations were observed between the phenolic content and sensory attributes and vice versa. The quality of wine cannot be concluded by chemical or sensory analysis alone, but the data sets are complementary. Although the phenolic concentration of wines made with S. cerevisiae strain (VIN 13) and T. delbrueckii (M2/1) were similar in measured phenolic concentrations, they had different sensory attributes. Wines made during the 2013 vintage indicated the importance of the use of a strain with higher enzyme activity and high fermentation rate. There is minimal to no skin contact in white winemaking. Therefore, the use of a yeast strain with an increased enzyme activity can facilitate the extraction of phenolics from grape, resulting in wine with improved quality.

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Suvac, Serghei. "Ensaios com alternativos de madeira e taninos enológicos em vinho tinto. Efeitos na composição química e análise sensorial." Master's thesis, ISA, 2013. http://hdl.handle.net/10400.5/6493.

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Mestrado em Viticultura e Enologia - Instituto Superior de Agronomia / Faculdade de Ciências e Tecnologia. Universidade do Porto
The aim of this study is to evaluate the effects of oak alternatives in red wine. The alternatives have been used: tannins of control enological tannin, tannin and extract of oak wood "Dialog", used doses were minimum, average and maximum. After one month aging in 10L bottles chemical composition and sensory analysis were evaluated. At the beginning of evaluation general analysis of wine were determined (% vol, pH, SO2, sugar, etc.) and analyzes which linked to phenolic compounds, (intensity and color tone, total anthocyanins, coloured anthocyanins, ionization index, polymeric pigments, total pigments, polymerization index, index of total polyphenols, total phenols, and CIELab analyze of color. Analyses showed that there are no major differences between samples, only the wine with concentration of oak extract 0.225 g/l have slightly higher values of total phenols, total polyphenols index and total anthocyanins. In terms of sensory analysis, in the tasting panel found no major differences in the overall assessment parameter, aroma and taste balance, some differences were found in wine with oak extract dose 0.225 g/l.

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Nunes, Inês Filipa Santos. "Evolution of phenolic and sensorial characteristics of rosé wines aged with different alternative wood chips." Master's thesis, ISA, 2017. http://hdl.handle.net/10400.5/14840.

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Mestrado em Viticultura e Enologia / Instituto Superior de Agronomia
The aim of this study was evaluating the effects of cherry (Prunus avium) and oak (Quercus petraea) chips in the phenolic, volatile and sensorial profile of a Portuguese rosé wine, made from Touriga attempting to understand whether the application of cooperage, including alternative woods, is potentially enhancing. For this purpose, several chemical analyses were carried out; for musts (at 0, 2, 6, 8,10 and 20 fermentation days), total phenols, non-flavonoids, chromatic characteristics, and colour due to copigmentation were assayed. For the wines (sampled at 40, 60 and 80 storage days), the same analysis took place, as well as HPLC determination of individual anthocyanins, polyamide column extraction and HPLC determination of proanthocyanidins, proanthocyanidin separation by degree of polymerization and sensory analysis. Both woods improved colour intensity and pigment stability, which was significantly more relevant when using cherry wood, and phenolic content was consistently higher with this wood, in comparison with the control and oak wines, the latter even showing less total phenols than the control at one storage point. Both also had a considerably larger proportion of coloured anthocyanins than the control, more pronounced in the wines fermented and aged with chips, and with no discernible dominance of any wood type, and oak wood induced an increase of malvidin-3-glucoside in storage. Cherry wood also showed a much higher concentration of monomeric procyanidins, namely (+)-catechins, with a possible effect of contact time. From sensory analysis, wines aged and/or fermented with wood chips always scored highest in overall rating (CHFA at 40 storage days, CHF at 60 and OKFA at 80), significantly improving colour intensity and overall quality, as well as woody aromas, which developed more intensely in the wine fermented and aged with oak chips. There were no definite differences between contact time when using wood, and results were sometimes irregular and with considerable associated error
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Lira, Miranda Eugenio Cristian. "Bentonite fining during different white winemaking stages: effect on the chemical and sensory properties of the wine." Doctoral thesis, Universitat Rovira i Virgili, 2013. http://hdl.handle.net/10803/125664.

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This thesis shows the results obtained from adding bentonite at different stages of the alcoholic fermentation in protein stability and reducing the bentonite required to reach stability. Results reflect the effect of this practice on alcoholic fermentation, chemical composition of wines, protein content and profile, aromatic profile and foam quality. The study was carried at pilot and industrial scale, with several grape varieties, in different geographical areas and during three vintages. The advantage of using bentonite during alcoholic fermentation was established, especially in moderate doses, making the addition from the middle of fermentation, obtaining more stable wines with less bentonite. Wines that were stabilized by bentonite treatment during fermentation were the best sensorial evaluated. Reproducibility between scales was confirmed for almost every parameter checked. Protein fractions and bentonite stabilizing dose for the different white wines was also identified and correlated. A commonly used technique was improved, achieving better quality wines.
En esta tesis se presentan los resultados de adicionar bentonita en diferentes etapas de la fermentación alcohólica en la estabilidad proteica y en la reducción de la dosis estabilizante de bentonita. Se aprecia el efecto en la fermentación, la composición química de los vinos, el contenido y perfil proteico, el perfil aromático y la calidad de la espuma. El estudio fue realizado a escala piloto e industrial, con diferentes variedades de uva, en distintas zonas geográficas y durante tres vendimias. Se estableció la ventaja de usar bentonita durante la fermentación, especialmente en dosis moderadas a partir de la mitad de la fermentación, obteniéndose vinos más estables con menos bentonita y mejor evaluados sensorialmente. Se confirmó la reproductibilidad entre escalas para la mayoría de los parámetros evaluados. Se identificaron y correlacionaron fracciones proteicas con dosis estabilizante de bentonita. Así se mejoró una técnica comúnmente usada para obtener vinos de mejor calidad.

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Goldsworthy, S. A. "Pre-fermentation maceration of pinot noir wine." Lincoln University, 1993. http://hdl.handle.net/10182/1058.

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Two pre-fermentation treatments were investigated in Pinot noir (Vitis vinifera L.) wines. The effects of cold maceration and carbonic maceration on the wines' composition, colour parameters and sensory properties were examined. Cold maceration is a winemaking technique used to increase non-alcoholic extraction in Pinot noir winemaking prior to fermentation. It involves holding crushed grapes with approximately 100-150 mg l⁻¹ SO₂ at low temperatures and is thought to increase the colour, aroma and flavour of the resulting wines. Carbonic maceration uses whole bunches that have undergone anaerobic metabolism to produce characteristically fruity and spicy wines. Pre-fermentation cold maceration produces wines that are higher in titratable acidity and monomeric anthocyanin content, but lower in colour density, hue and polymeric pigments. Reducing the maceration temperature below 10°C has little effect. Carbonic maceration produces wines that are lower in titratable acidity, monomeric anthocyanin content, and colour density but are higher in colour hue and amount of polymeric pigments. Quantitative descriptive analysis was used to define the effects of these pre-fermentation maceration treatments on the sensory characteristics of the resulting wine. Trained panel members found that there were no discernable sensory differences in the compositional parameters despite measurable chemical differences. Investigation into the aroma and flavour characteristics of the wines found that carbonic maceration produces wines that were lower in berry aroma and higher in acetate or ester-type aromas than the control wines. These wines were considered to have specific raspberry, floral, sugar, cherry and chemical aromas. This chemical note was also observed in the flavour of the carbonic maceration wines. The temperature of the cold maceration process has no major effect on the aroma and flavour of the resulting wines. However, the 10°C maceration was higher in woody/tobacco aroma than the 4°C maceration, and the 10°C treatment was also higher in bitter flavour than all the other treatments. Cold maceration wines were found to have specific mixed berry, dried fruit and sweet-oxidised aroma characters, together with a blackberry flavour note.

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Santos, Filipa Ferreira Reis Cardoso dos. "Use of alternative wood chips from new botanical species. Their impact on phenolic composition and sensory properties of a rose wine from Touriga Nacional grape variety." Master's thesis, ISA, 2017. http://hdl.handle.net/10400.5/14854.

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Mestrado em Viticultura e Enologia / Instituto Superior de Agronomia / Faculdade de Ciências. Universidade do Porto
The aim of this study was to evaluate the effects that acacia (Robinia pseudoacacia), cherry (Prunus avium), American and French oak (Quercus alba and Quercus petraea) wood chips and the evolution of the phenolic composition and sensorial properties of a rose wine made from Touriga Nacional grape variety during a storage period of 20 days. Chemical analysis were carried out: total phenols, flavonoid and non-flavonoid phenols, chromatic characteristics and tanning power. At the end of the assay a sensory analysis was performed. Three sensorial parameters group were considered: aspect, aroma and taste. The results showed some statistical significant differences in most of the phenolic parameters, mainly in the wines without fining. Thus, it was possible to conclude that there are differences between the impact of different botanic species used. In particular, acacia wood chips thus, the results suggest a significant impact on phenolic content of rose wine during the short period of stage, by the use of acacia wood chips. Concerning to sensorial analysis, two situations could be observed: a slight preference for the wine treated with cherry wood chips – without fining. On the other hand, there was a slight preference for the control wine (without added wood) – after fining
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Ifie, Idolo. "The effect of processing conditions on the bioactive compounds, aroma profile and sensory attributes of wine from Hibiscus sabdariffa." Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/15674/.

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Hibiscus sabdariffa (H. sabdariffa) is a rich source of bioactive phytochemicals with potential health benefits. Based on its reported use in folk medicine for the treatment of hypertension and recently type 2 diabetes, the plant has gained considerable commercial importance as a functional food. Three varieties of H. sabdariffa were analyzed for their phytochemical content and inhibitory potential on carbohydrate-digesting enzymes as a basis for selecting a variety for wine production. The dark red variety was chosen as it was highest in phenolic content and partially inhibited α–glucosidase (maltase), with delphinidin 3-O-sambubioside, cyanidin 3-O-sambubioside and 3-O-caffeoylquinic acid accounting for 65 % of this activity. None of the varieties significantly inhibited α–amylase. Regarding H. sabdarifa wine, the effect of fermentation (20 and 30 ˚C) and ageing (6, 15 and 30 °C) temperatures on the phytochemical composition and bioactivity of Roselle wine was investigated for a period of 40 days and 12 months respectively. The main change in phytochemical composition observed during fermentation was the hydrolysis of 3-O-caffeolquinic acid and the concomitant increase of caffeic acid irrespective of fermentation temperature. Wine fermented at 20 ˚C was slightly more active for α–glucosidase inhibition with more fruity aromas, but there were more flowery notes at 30 ˚C. Although ageing temperature did not produce an obvious trend in concentrations of most of the volatiles analysed, its impact was clearly demonstrated in the final concentrations of diethyl succinate which increased with higher ageing temperature. The data on the overall quality rating of roselle wine by a sensory panel showed that neither fermentation nor ageing temperatures produced any significant difference (p ≥ 0.05) in the wine samples. This study demonstrates that processing of H. sabdariffa into wine represents a promising alternative to expanding the functional properties of this crop.

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Bou, Nader Khalil. "Grapevine age : Impact on physiology and berry and wine quality." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0329/document.

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L’âge de la vigne et sa relation avec la qualité du vin sont des sujets d’intérêt récurrents, tant scientifiques qu’économiques. Les consommateurs et acteurs de la filière vitivinicole semblent s’accorder à propos de la capacité des vieilles vignes à produire des vins de caractère supérieur. Malgré les recherches en cours, la validité de ce point de vue reste débattue et les questions concernant les mécanismes à travers lesquels de vieilles vignes aboutiraient à des vins qualité supérieure restent nombreuses. Pour tenter d’y répondre, l’impact de l’âge des vignes sur la physiologie, la tolérance au stress hydrique, ainsi que la qualité des baies et du vin ont été étudiés dans un vignoble expérimental constitué de plants de Vitis vinifera L. cv. de matériel génétique identique (Riesling de clone Gm 239 greffé sur 5C Teleki) mais aux dates de plantation différentes.En 2014 et 2015, les vignes plantées en 2012 n’avaient pas encore atteint leur plein potentiel et avaient une productivité végétative et un rendement significativement inférieurs à ceux des vignes plantées en 1995 et 1971. Par ailleurs, les vignes plantées en 2012 n’ont pas été soumises au même traitement d’enherbement que les vignes plus âgées pendant cette période afin de prévenir une compétition excessive pendant leur établissement. La capacité inférieure de ces vignes et l’absence d’enherbement ont mené à une plus grande exposition des grappes à la lumière et une plus grande accumulation d’azote, ce qui s’est traduit par une plus grande concentration en acides aminés, monoterpènes, norisoprénoides, et flavonols en 2014 et 2015. Les années suivantes (2016 et 2017), le rendement et le poids des bois de taille de ces vignes, ainsi que la composition des baies, étaient comparables à ceux des vignes plus âgées. Les paramètres de maturité technologique (°Brix, l’acidité totale et le pH de moûts) n’ont pas été significativement affectés par l’âge des vignes. […]Des analyses sensorielles et chimiques ont été réalisées en 2017 sur des vins de millésimes précédents. Les vins des plus jeunes vignes ont été associés à des arômes de fruits mûrs et de l’arôme de pétrole typique du Riesling. Ces vins ont aussi été identifiés par de plus hautes concentrations de monoterpènes et norisoprénoides potentiels et de composés soufrés volatils, en 2014 et 2015 uniquement. Les profils sensoriels et chimiques de vins issus des vignes plantées en 1995 et 1971 étaient dépendants du millésime mais pas de l’âge des vignes. Les profils des vins produits en 2016 étaient en superposables pour les trois groupes d’âge.Les travaux décrits dans ce manuscrit de thèse sont uniques, du fait notamment que le vignoble dans lequel ils ont été conduits a été conçu spécifiquement pour étudier l’effet de l’âge de la vigne dans des conditions environnementales comparables. Une fois que les vignes les plus jeunes ont atteint leur potentiel fructifère et ont été conduites de la même manière que les vignes plus âgées, leur productivité, la composition de leurs baies et la qualité des vins qu’elles produisent ont convergé avec celles des deux autres groupes. Plus intéressant encore, des vignes âgées de 19 et 43 ans se sont comportées de la même façon tout au long de l’étude et ont abouti à des vins comparables en termes d’analyses sensorielles, ce qui va à l’encontre de l’idée reçue qui veut que les vignes les plus âgées produisent des vins de qualité différente.Des travaux précédents ont démontré que la productivité des vignes, quel que soit leur âge, pouvait être expliquée par les réserves de bois et par la taille du tronc. Pour avoir une meilleure idée des différences liées aux réserves, la technique dite « structure-from-motion with multi-view stereo-photogrammetry » (SfM-MVS) a été testée pour mesurer l’épaisseur des troncs et leur volume. Cette technique qui permet la création de modèles tridimensionnels géo-référencés et à l’échelle a pu générer des modèles précis de tronc de vignes plantées en champ
Vine age and its relation to the quality of the wine are topics of recurring interest, both scientific and economic. Consumers and actors in the wine sector seem to agree on the ability of old vines to produce wines of superior character. Despite ongoing research, the validity of this point of view remains debated and questions about the mechanisms through which old vines would end up with superior quality wines remain numerous. To try to answer them, the impact vine age on physiology, tolerance to water stress, and berry and wine quality were studied in an experimental vineyard planted with Vitis vinifera L. cv. of identical genetic material (Riesling Gm 239 grafted on 5C Teleki) but planted in different years.In 2014 and 2015, the vines planted in 2012 had not yet reached their full potential and had a significantly lower vegetative productivity and yield than the vines planted in 1995 and 1971. Moreover, the vines planted in 2012 were not subjected to the same grass treatment as older vines during this period to prevent excessive competition during establishment. The lower capacity of these vines and the absence of cover crop led to greater exposure of clusters to light and greater nitrogen accumulation, which resulted in a higher concentration of amino acids, monoterpenes, norisoprenoids, and flavonols in 2014 and 2015. In the following years (2016 and 2017), the yield and pruning weight of these vines, as well as their berry composition, were comparable to those of the older vines. The parameters of technological maturity (° Brix, total acidity and must pH) were not significantly affected by vine age.Vines planted in 1995 and 1971 showed similar physiological characteristics throughout the study with the exception of a higher incidence of esca syndrome in the older group. This disease was responsible for the decline in the total yield of vines planted in 1971, but individual yield per vine was equivalent for both groups.Sensory and chemical analyzes were conducted in 2017 on wines from previous vintages. The wines of the youngest vines were associated with aromas of ripe fruit and the kerosene aroma that is typical of Riesling. These wines were also identified by higher concentrations of potential monoterpenes and norisoprenoids and volatile sulfur compounds in 2014 and 2015 only. The sensory and chemical profiles of wines from vineyards planted in 1995 and 1971 were dependent on the vintage but not on the age of the vines. The wine profiles produced in 2016 were overlapping for the three age groups.The works described in this thesis manuscript are unique, particularly because the vineyard in which they were conducted was designed specifically to study the effect of the age of the vine under comparable environmental conditions. Once the youngest vines reached their fruiting potential and were conducted in the same way as the older vines, their productivity, the composition of their berries and the quality of the wines they produce converged with those of the two other groups. More interestingly, vines aged 19 and 43 years behaved similarly throughout the study and resulted in wines comparable in terms of sensory analysis, which goes against the an idea that the older vines produce wines of a different profile.Previous studies have shown that the productivity of the vines, whatever their age, could be explained by the wood reserves and the size of the trunk. To have a better idea of differences linked to reserves, the structure-from-motion with multi-view stereo-photogrammetry (SfM-MVS) method was tested to measure trunk thickness and volume. The technique, which allows the creation of scaled, georeferenced 3D models based on photographs, was able to produce accurate models of field-grown grapevine trunks

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Delia, Lorenzo. "Use of alternative wood chips from new botanical species. Their impact on phenolic composition and sensory properties of a white wine from Encruzado grape variety." Master's thesis, ISA-UL, 2016. http://hdl.handle.net/10400.5/12217.

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Mestrado Vinifera Euromaster - Instituto Superior de Agronomia - UL
The aim of this study was to evaluate the effects that Acacia (Robinia pseudoacacia), Cherry (Prunus avium), American oak (Quercus alba) and French oak (Quercus petraea) wood chips have on the evolution of the phenolic composition and sensorial properties of a white wine from Encruzado grape variety, during a storage period of 4 weeks. Chemical analysis were carried out: total phenols, flavonoid and non-flavonoid phenols, chromatic aspects, susceptibility to browning and tanning power. A sensory analysis was also performed at the end of the experiment. The results showed statistically significant differences between the treatments in most of the phenolic analysis, allowing us to establish a difference between the control wine and the wines aged in contact with the different wood chips species. In particular, acacia wood chips seemed to influence greatly the phenolic aspects of the white wine used in a short aging period. Generally, the wine aged with cherry chips presented intermediate values between acacia sample and the standard wine. Concerning the sensory analysis, there was a slight preference for the wine aged in contact with acacia wood chips, suggesting its suitability for aging for this kind of wine, as well as for cherry wood that has shown good aptitude

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Chapman, Dawn Marie Ahlgren. "Crop yield and vine irrigation effects on the sensory quality of Vitis vinifera L., cv. Cabernet Sauvignon and Sangiovese wine /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2004. http://uclibs.org/PID/11984.

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Biasoto, Aline Camarão Telles 1981. "Vinhos tintos de mesa produzidos no Estado de São Paulo : caracterização do processo de fabricação, de parametros fisico-quimicos, do perfil sensorial e da aceitação." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/254972.

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Orientadores: Maria Aparecida Azevedo Pereira da Silva, Flavia Maria Netto
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
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Resumo: No Estado de São Paulo, a produção de vinhos de mesa de uvas americanas e/ou híbridas, supera grandemente a de uva Vitis vinífera. No entanto, pouco conhecimento se tem sobre a tecnologia de fabricação utilizada para a elaboração desses vinhos no Estado de São Paulo, seu nível de segurança, perfil sensorial e aceitabilidade entre os consumidores paulistas. Assim, o objetivo da presente pesquisa foi caracterizar o processo de fabricação das vinícolas paulistas, avaliar o nível de implantação de sistemas básicos da qualidade e as condições higiênico-sanitárias destas vinícolas, caracterizar o perfil sensorial, a aceitação e parâmetros físico-químicos dos vinhos tintos por elas produzidos. Para a realização desse trabalho, após convite, foram selecionadas para participar da pesquisa 10 vinícolas artesanais e industriais do Estado de São Paulo. Todas encaminharam um de seus vinhos tintos secos para análises físico-químicas e sensoriais, os quais, em sua maioria, eram elaborados a partir de uvas americanas e/ou híbridas, e pertenciam à safra 2006. Sete dessas dez vinícolas foram selecionadas para participar da pesquisa de campo, por meio da qual, caracterizou-se as etapas de elaboração dos vinhos, desde o cultivo das uvas até o engarrafamento da bebida. Durante a visita, foi também preenchida a lista de verificação (check list) da legislação vigente brasileira, de forma a avaliar o cumprimento das Boas Práticas de Fabricação (BPF) e dos Procedimentos Operacionais Padronizados (POP¿s), bem como das condições higiênico-sanitárias dessas vinícolas. Através de Análise Descritiva Quantitativa (ADQ®), uma equipe de 12 julgadores selecionados e treinados desenvolveu a terminologia sensorial descritiva e o perfil sensorial dos vinhos. A intensidade de cada descritor foi avaliada em seis repetições para cada amostra, através de uma escala não estruturada de nove centímetros, ancorada em seus extremos com os termos de intensidade "fraco" e "forte". Os dados descritivos foram analisados por Análise de Variância (ANOVA), teste de médias Tukey (p= 5%) e Análise de Componentes Principais (ACP). Na sequência, 120 consumidores de vinhos tintos secos avaliaram através de escala hedônica híbrida, cada uma das dez amostras com relação a aparência, impressão global, aroma e sabor. Os dados afetivos foram analisados através de Mapa de Preferência Interno (MDPREF), ANOVA e teste de Tukey (p= 5%) para comparação das médias. Os vinhos foram também caracterizados quanto ao: teor de açúcares redutores, sólidos solúveis (ºBrix), compostos fenólicos totais, acidez total, acidez volátil, dióxido de enxofre livre, pH, graduação alcoólica, extrato seco e extrato seco reduzido, relação álcool/ extrato seco reduzido (p/p) e metanol. Os resultados físico-químicos foram também analisados por ANOVA e teste de médias de Tukey (p = 5%). Os parâmetros químicos dos vinhos avaliados, em geral, enquadraram-se nos Padrões de Identidade e Qualidade (PIQ¿s) estabelecidos pela legislação brasileira. Entretanto, de um modo geral, as vinícolas visitadas demonstraram estar em condições higiênico-sanitárias insatisfatórias; apenas um estabelecimento foi classificado no Grupo 1, atendendo a mais de 76% dos itens da lista de verificação. As amostras apresentaram perfis sensoriais bastante distintos entre si, diferindo significativamente (p = 0,05) com relação à maioria dos 33 descritores desenvolvidos através da análise descritiva, quais sejam: cor roxa, cor vermelha/rubi, viscosidade aparente e translucidez; notas aromáticas de uva, suco de uva, doce, amadeirado, alcoólico, frutas secas, frutas vermelhas, ácido, fermento, cogumelo, enxofre, chá, floral cítrico, floral não cítrico e vegetativo; notas de sabores descritas como uva, suco de uva, gosto doce, amadeirado, alcoólico, frutas secas, frutas vermelhas, ácido acético, gosto azedo, gosto amargo, semente e fermentado; além de sensações bucais de corpo e adstringência. Com relação aos seus perfis sensoriais, os vinhos segmentaram-se principalmente em função do varietal das uvas utilizadas na elaboração dos mesmos, a despeito das bebidas terem sido elaboradas por diferentes vinícolas, processos, etc. Vinhos elaborados a partir de uvas Bordô apresentaram notas mais intensas de aromas e sabores frutados (uva, suco de uva e frutas vermelhas) aroma e gosto doce, e aroma floral não cítrico (notadamente aroma de rosas); notas sensoriais realmente esperadas em vinhos de mesa de uvas americanas e/ou híbridas. Destacaram-se na preferência dos consumidores um vinho elaborado com o varietal Seibel 2 (¿Corbina¿), e vários contendo uvas Bordô
Abstract: In the State of Sao Paulo, Brazil, the production of table wine from American and/or hybrid grapes strongly surpasses the production from Vitis Vinifera grape varieties. However, in this State, there is little knowledge regarding the technology used to manufacture these wines, their level of food safety, sensory profiles and acceptability among the Brazilian consumers. Thus, the objectives of the present research were to characterize the manufacturing processes used by Sao Paulo¿s wineries, analyzing their quality control systems, sanitary conditions and their wines sensory profile, acceptance and chemical parameters. Thus, ten wineries joined the research, sending for analysis, a sample of their dry red table wine, from the 2006's crop. The majority of the wines were produced from hybrid or American grapes. Seven of the ten wineries were visited and all stages of their production plant was inspected, from the grapes plantation to the wine bottling. A checklist was filled out in order to verify the wineries performance regarding procedures of ¿Good Manufacturing Practices¿ (GMP) and Standard Operational Procedures (POP¿s), as well as sanitary conditions. Using Quantitative Descriptive Analysis, 12 trained panelists developed the wines lexicon and sensory profiles. Panelists rated the intensity of each attribute, using a 9 cm non-structure scale, anchored in its left and right extremes with terms ¿weak¿ and ¿strong¿ respectively. Each wine was evaluated in six replications by each panelist. The resulting data was evaluated using analysis of variance (ANOVA), Tukey test (p = 5%), and the Principal Component Analysis (PCA). Sequentially, 120 consumers evaluated the overall liking of all ten wines, using a hybrid hedonic scale. Additionally, the consumers evaluated how much they like/disliked the sample¿s appearance, aroma and flavor. The affective data was analyzed through the Internal Preference Map (MDPREF), ANOVA and Tukey test (p= 5%). Finally, the wines were analyzed with respect to reducing sugars, pH, total acidity, volatile acidity, total phenols, free sulphur dioxide, pH, methanol, soluble solids (oBrix), total solids, alcohol content and methanol content. The physical-chemical results were analyzed by ANOVA and Tukey test (p = 5%). Overall, the wines chemical parameters complied with the Brazilian legislation for red table wine. Nevertheless, several wineries showed substandard sanitary conditions. The wines possessed very distinct sensory profiles, differing significantly among them (p = 5%) in most of the 33 descriptors, such as: purple color, red/ruby color, visual viscosity; aroma and/or flavor notes of grape, sweet, woody, alcohol, dried fruit, berry, sour, yeasty, mushroom, sulfur, tea, floral citrus, rose and vegetative among others. Despite the fact that production had taken place at different wineries using different processes, wines produced from the same varietals showed similar sensory profiles, The wines produced with Ives (Bordô) grapes showed highest intensities of fruity aroma and flavor (grape, juice grape and berry fruit), sweet aroma and taste and rose aroma; all sensory attributes expected in wines produced from American and/or hybrid grapes. Among the ten wines evaluated, the consumers preferred one sample produced from Seibel 2 variety (¿Corbina¿) and the wines made from Ives (Bordô) grapes
Mestrado
Consumo e Qualidade de Alimentos
Mestre em Alimentos e Nutrição

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Paissoni, Maria Alessandra. "Characterization of anthocyanins and condensed tannins from grapes and their qualitative incidence on astringency and bitterness sensory properties." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0383/document.

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Dans le vin rouge, les composés phénoliques sont souvent associés à la qualité du produit. Parmi eux, les anthocyanes sont responsables de la couleur du vin rouge et chaque cépage possède un génome spécifique déterminant le profil anthocyanique de chacun. Les pratiques culturales peuvent influencer l’accumulation de ces molécules dans la baie de raisin, tandis que les différentes techniques fermentaires peuvent modifier leur extraction. Les flavanols monomères, oligomères et polymères des pépins et des pellicules contribuent à l’amertume et l’astringence des vins. Pendant la vinification et l’élevage, ceux-ci réagissent avec les anthocyanes modifiant les propriétés du vin. De nombreuses publications concernant les caractéristiques sensorielles des flavanols ont été réalisées, alors que la contribution sensorielle des anthocyanes est encore mal connue. Cette thèse se décompose en deux parties. La première partie s’intéresse à l’étude de l’utilisation d’ozone gazeux comme technique pré-fermentaire sur les cépages rouges Nebbiolo et Barbera après récolte et pendant le passerillage. L’ozone est une technique innovante pour la réduction des contaminations microbiennes et la réduction du dioxyde de soufre. L’influence de cette technique sur les parois cellulaire des pellicules, sur l’extraction, la concentration en flavanols et en anthocyanes pendant la macération a été évaluée. L’étude montre que l’ozone possède un impact sur la macération des raisins, induisant une extraction plus importante des anthocyanes dans le Nebbiolo. En revanche, l’ozone n’influence ni les anthocyanes moléculaires, ni le profil variétal de chaque cépage. Pendant le passerillage, l’inverse a été étudié. L’extraction des anthocyanes dans le Nebbiolo est diminuée. A l’inverse, bien que moins d’anthocyanes soient retrouvées dans le raisin de Barbera, le traitement ne possède aucun impact sur l’extraction de celles-ci. Concernant les flavanols, l’extraction est moins influencée par le traitement à l’ozone. Des différences ont été retrouvées dans le cépage Nebbiolo. Les flavonols sont plus concentrés après le traitement avec l’ozone sur les raisins post-récolte, alors qu’ils diminuent pendant le passerillage. La modification causée sur la paroi cellulaire par l’ozone ainsi que la dureté des pellicules pourraient prédire l’extraction des anthocyanes et des flavanols, grâce à des analyses multi-variées. En conséquence, le traitement avec l’ozone doit être adapté en fonction du cépage et du produit final désiré. Dans la deuxième partie, les anthocyanes des raisins ont été extraites à partir des raisins et ces extraits ont été fractionnés en trois fractions, glucoside, acetyl-glucoside et cinnamoyl-glucoside, par Chromatographie de Partage Centrifuge (CPC) et CLHP (Chromatographie Liquide Haute Performance) préparative. L’évaluation de l’astringence a été réalisée par des analyses de précipitation protéique avec une protéine modèle BSA (Bovine Serum Albumin) et des protéines salivaires, les anthocyanes réagissant avec ces dernières. Les analyses sensorielles et l’évaluation de l’astringence ont été combinées. La concentration en anthocyane diminue après le traitement avec les protéines salivaires, dans l’extrait total et dans les fractions, en particulier les cinnamoyl-glucosides apparaissent comme les plus réactives avec les protéines salivaires. Les seuils de perception gustatifs ont été calculés avec la méthode “Best estimate threshold” dans le vin modèle. Les fractions acétyl-glucosides et cinnamoyl-glucosides, suivies de la fraction glucoside, possèdent des seuils de perception plus bas aux concentrations retrouvées dans les vins. Les descripteurs associés à ces fractions sont l’amertume et l’astringence. Ces résultats démontreraient que les anthocyanes apportent une contribution sensorielle dans la perception du vin en bouche, corrélée à l’acétylation des molécules
In red wine, phenolic compounds are generally associated with the quality of products. Among them, anthocyanins extracted from skins are responsible for wine colour. The grapevine genomes determine the anthocyanins profiles, but several factors in the vineyard can influence their accumulation, as well as post-harvest techniques can modify their extraction during winemaking. Monomeric, oligomeric and polymeric flavanols from skins and seeds contribute to astringency and bitterness of wine and during winemaking and ageing complexes formation with anthocyanins modifies wine characteristics. Several publications are available to understand flavanols sensory characteristics, whereas anthocyanins role has not consensus in scientific literature. This PhD thesis is composed by two parts. The first part deal with the evaluation of the use of gaseous ozone as post-harvest technique in red wine grapes Nebbiolo and Barbera used on both fresh grape and during withering. Ozone treatment is an innovative technology proved to avoid mycobiota spoilage and preserving from the use of sulphur dioxide. Its influence on flavanol and anthocyanin contents and extractabilities during maceration was evaluated, considering skin cell wall modification. In fresh grape, ozone influenced skin maceration for both the varieties, leading to a higher anthocyanin extraction in Nebbiolo grapes and lower in Barbera. Ozone did not influence the final individual anthocyanin extractability, respecting the varietal anthocyanin fingerprint. During dehydration, opposite trend was found: in Nebbiolo reported no change in the content of total anthocyanins just after ozone-assisted dehydration, but their extraction yield was lower. On the contrary, although lower contents of anthocyanins were found in Barbera grapes no differences in final extractability was found. Regarding oligomeric and polymeric flavanols, their extractability was less affected by the ozone treatment. Only in Nebbiolo, both oligomeric and polymeric flavanol extraction was increased in fresh grape, whereas it is slightly decrease during dehydration. The ozone-induced modification of skin cell wall composition together with skin hardness parameters fitted well in multivariate models to predict anthocyanins, oligomeric flavanols and polymeric flavanols extraction. Therefore, the ozone treatment should be adapted depending on the variety and on the target wine. In the second part, grape anthocyanins were isolated depending on the acylation patterns, i.e. glucoside, acetyl-glucoside, and cinnamoyl-glucoside by a combination of centrifugal partition chromatography (CPC) and preparative-HPLC. Protein precipitation analyses to assess astringency and sensorial analysis were carried out. Anthocyanins reacted with both bovine serum albumine and salivary proteins, in different extent, since higher interaction between anthocyanins and salivary proteins was found with a significative reduction of total extract and fractions glucoside, acetyl-glucoside, and cinnamoyl-glucoside. The latter in particular is the more reactive to salivary proteins. Sensorial analysis was carried out as detection threshold test. Best estimated threshold (BET) of anthocyanins were resulted in wine-range scale, in particular acetyl-glucoside and cinnamoyl-glucoside BET are lower of glucoside threshold, and descriptors reported were astringency and bitterness. These results show that anthocyanins can be detected as in-mouth properties contributors, and the magnitude of their involvement is related to anthocyanins acylation

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Hickey, Cain Charles. "Vines of different capacity and water status alter the sensory perception of Cabernet Sauvignon wines." Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/42667.

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Reducing disease and increasing fruit quality in vigorous vineyards with dense canopies is demanding of time and resources; unfortunately, vineyards of this nature are common in humid environments. This study investigated the effectiveness with which vine capacity and water status could be regulated as well as if they related to fruit quality and wine sensory perception. The treatments regulating vine size and water status were under-trellis groundcover, root manipulation, rootstocks, and irrigation. Treatments were arranged in a strip-split-split plot design before the introduction of the irrigation treatment resulted in incomplete replication in each block. Treatment levels were under-trellis cover crop (CC) compared to under-trellis herbicide (Herb); root restriction bags (RBG) compared to no root manipulation (NRM); three compared rootstocks (101-14, 420-A, riparia Gloire); low water stress (LOW) compared to high water stress (HIGH). Vines grown with RBG and CC regulated vegetative growth more so than conventional treatments, resulting in 56% and 23% greater cluster exposure flux availability (CEFA). High water stress (HIGH) and RBG reduced stem water potential and discriminated less against 13C. Vines grown with RBG and CC consistently reduced harvest berry weight by 17 and 6% compared to conventional treatments. Estimated phenolics were consistently increased by RBG and were correlated with berry weight, vine capacity and CEFA. Sensory attributes were significantly distinguishable between wines produced from vines that differed in both vine capacity and water status, amongst other responses. Treatments have been identified that can alter the sensory perception of wines, with the potential to improve wine quality.
Master of Science

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Castilhos, Maurício Bonatto Machado de [UNESP]. "Vinificação em tinto de uvas americanas: efeito das técnicas de pré-secagem das uvas e de chapéu submerso nos perfis químico e sensorial." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/136357.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
A produção brasileira de vinhos encontra-se em constante especialização e tem como objetivo incrementar a qualidade dessas bebidas a fim de atender e superar as expectativas dos consumidores. Diante desse contexto, algumas entidades governamentais pesquisam o melhoramento genético de uvas almejando produzir matérias-primas com características singulares a fim de elaborar vinhos com qualidade ímpar e de caráter regional. Adicionalmente, cientistas da área pesquisam variações no processo de vinificação e, através dessas técnicas, promovem variações no perfil químico dos vinhos, respondendo positivamente no perfil sensorial descritivo e de aceitação. Esse estudo pesquisou os efeitos da pré-secagem das uvas e o emprego do chapéu submerso e explorou o comportamento químico e sensorial de vinhos elaborados com uvas americanas e híbridas. Os resultados mostraram que os vinhos elaborados pelo processo de pré-secagem das uvas apresentaram forte degradação de compostos fenólicos como antocianinas e flavonóis, sendo os flavan-3-óis (galoilados ou não) e proantocianidinas os que apresentaram maior resistência ao calor produzido pela secagem. De uma forma geral, tais vinhos foram descritos como amargos, adstringentes, encorpados, pungentes e persistentes por apresentarem elevada concentração desses compostos fenólicos. Os vinhos elaborados pelo processo de chapéu submerso não apresentaram diferenças significativas nos conteúdos de antocianinas, piranoantocianinas e flavonóis quando comparados aos vinhos elaborados pelo processo tradicional de vinificação, sendo descritos com elevada intensidade de cor e matiz violeta, além de apresentarem, em alguns casos, aroma foxado e frutado evidente. Apresentaram elevada aceitação em alguns casos, sendo considerados como alternativa ao tratamento tradicional.
Brazilian wine production is in constant specialization and aims to enhance the quality of red wines in order to meet and exceed consumer expectations. Thus, some governmental entities develop genetic improvement programs aiming at producing grapes with singular features that will be employed in the production of regional wines, i.e., wines whose features indicate their origin of production. Moreover, scientists from enological area study the variations in winemaking aiming at promoting such improvement on the chemical properties of wines, enhancing their acceptance sensory profile. Therefore, this study aimed at analyzing the effects of grape pre-drying and submerged cap in order to explore the chemical and sensory behavior of red wines produced from Vitis labrusca grapes and their hybrids. The results showed that the wines produced from pre-drying process presented relevant degradation of the phenolic compounds, mainly anthocyanins and flavonols; and flavan-3-ols (galloylated or not) and proanthocyanidins were the compounds that seemed to be less affected by the heat produced by the pre-drying procedure. In general, these wines were described as bitter, astringent, full-bodied, pungent and persistent to palate due to their high concentration of these aforementioned compounds. Wines produced form submerged cap winemaking presented no significant differences from the wines elaborated by traditional process concerning anthocyanin, pyranoanthocyanin and flavonol contents, and were described as colorful with intense violet hue and strong foxy and fruity aroma. These wines presented higher acceptance in some cases and were considered as an alternative to the traditional winemaking treatment.

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Reginato, Carlos Eduardo Roehe. "Impacto do transporte da uva sobre a composição química e o perfil sensorial de vinhos produzidos no Estado do Rio Grande do Sul." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2015. http://hdl.handle.net/10183/114968.

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O vinho fino é aquele produzido com uvas Vitis Vinifera. Um bom vinho deve apresentar um equilíbrio entre as suas características químicas e organolépticas. A uva precisa estar em condições físicas e bioquímicas adequadas para que o vinho resulte em qualidade máxima. O transporte e o tempo de espera para o processamento nas vinícolas constituem-se fatores importantes para a produção de vinhos. O trabalho teve como objetivo identificar o impacto destes fatores na qualidade dos vinhos finos produzidos no Estado do Rio Grande do Sul. A metodologia contemplou análises qualitativas e quantitativas realizadas com vinhos tintos e brancos produzidos com uvas nas safras de 2013 e 2014. Foram identificados fatores críticos que devem ser observados durante o transporte e o pré-processamento, os quais são vitais para a manutenção e integridade das uvas. Os resultados revelaram que o transporte e o tempo de espera para o processamento das uvas, modificam as características físico-químicas e sensoriais dos vinhos. As alterações observadas foram de diferentes intensidades em função das safras, da uva (Chardonnay e Merlot), da distância entre o local da colheita e da vinícola, e das temperaturas durante o transporte e o tempo de espera.
The fine wine is the one produced with Vitis Vinifera grape. A good wine must present a balance between chemical and organoleptic characteristics. The grape must be in adequate physical and biochemical conditions for the wine to reach the highest quality. The transport and the waiting time for processing at the wineries are important factors for the production of wines. The study aimed to identify the impact of these factors on the quality of the fine wines produced in the state of Rio Grande do Sul. The methodology included the qualitative and quantitative analysis carried out on red and white wines produced with grapes from the 2013 and 2014 harvest. Critical factors that should be observed during transport and pre-processing were identified, which are vital for the maintenance and integrity of the grapes. The results reveal that the transport and waiting time for processing changed the physical, chemical and sensorial characteristics of the wine. These changes were of different intensities depending on the crop, of the grape (Chardonnay and Merlot), the distance between the place of harvest and the winery, and the temperatures during transport and waiting time.

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Santos, Betania Araujo Cosme dos. "Compostos volateis e qualidade dos vinhos secos jovens varietal cabernet suavignon produzidos em diferentes regiões do Brasil." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/255043.

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Orientador: Maria Regina Bueno Franco
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
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Resumo: Apesar da importância do aroma e sabor para determinar a qualidade dos vinhos, praticamente não existe nenhum estudo sobre a composição de voláteis dos vinhos nacionais. Os poucos que existem utilizam ainda coluna empacotada e outros traçam apenas o perfil sensorial dos vinhos, sem fazer correlações dos dados com qualquer outro parâmetro. No presente trabalho estudou-se 11 vinhos seco varietal Cabernet Sauvignon oriundos das principais regiões produtoras do país: Serra Gaúcha e Campanha, no Rio Grande do Sul; do Vale do Rio do Peixe, em Santa Catarina e do Vale do São Francisco, região de Pernambuco/Bahia. Foram efetuadas análises dos constituintes químicos e minerais presentes, após a homogeneização de três garrafas de vinho. Os parâmetros físico-químicos foram determinados pelos métodos clássicos e os teores dos minerais cálcio, magnésio, ferro, cobre e zinco foram analisados por absorção atômica; potássio, lítio, sódio e rubídio por emissão de chama e o fósforo por colorimetria. As características sensoriais das amostras foram determinadas pelo uso da Análise Descritiva Quantitativa através de nove provadores selecionados e treinados. As amostras foram avaliadas em quintuplicata, em 11 sessões, utilizando blocos incompletos balanceados. O teste de aceitação também foi realizado e os dados avaliados utlizando-se o Mapa Interno de Preferência. Os componentes voláteis foram extraídos em triplicata de cada garrafa de vinho, através de uma técnica de extração em fase sólida utilizando coluna Lichrolut EN e eluíção com diclorometano, conforme metodologia já validada para análise de compostos voláteis em vinho. Os contituinte voláteis foram separados por duas colunas capilares de polaridades diferentes. A identificação dos voláteis foi realizada por espectrometria de massas, além da comparação dos índices de Kovats experimentais com os valores encontrados na literatura e comparação dos espectros dos compostos com os dos padrões disponíveis. O extrato da amostra de maior aceitação foi analisado pela técnica de cromatografia gasosa-olfatometria0 para identificar a contribuição dos diferentes compostos voláteis para o aroma global do vinho. Os resultados das análises físico-químicas mostraram que todos os vinhos estavam dentro dos padrões estabelecidos pela legislação vigente, sendo que os teores encontrados de acidez volátil foram considerados elevados. Os valores de pH também foram elevados, mas tal fato é esperado quando da avaliação de vinhos Cabernet Sauvignon. A análise de minerais mostrou que os teores de potássio estavam bem acima dos encontrados em literatura. A técnica estatística multivariada de Análise de Componentes Principais, aplicada ao teor dos componentes físico-químicos e dos minerais não foi capaz de discriminar as amostras em relação à sua origem geográfica. O emprego do Mapa Interno de Preferência demonstrou que a amostra 245 (Serra Gaúcha) foi a mais aceita pela equipe, sendo caracterizada por uma forte sensação de doçura, apesar do teor de açúcares (2,65±0,05 g/L), aroma frutado e de frutas vermelhas. Os vinhos da região nordeste obtiveram uma aceitação inferior junto aos consumidores, juntamente com a amostra 512 (Serra Gaúcha). Foram identificados pela primeira vez em vinhos nacionais, 39 compostos voláteis, sendo que 13 pertenciam à classe dos álcoois, 13 à dos ésteres, 7 à dos ácidos, 2 à das lactonas, além de 3 compostos carbonílicos e 1 composto fenólico. Apesar da variação da concentração dos compostos entre as amostras, o pico correspondente aos compostos 2-metil-1-butanol e 3-metil-1-butanol foi o mais abundante para todas as amostras, seguido pelo álcool feniletílico, lactato de etila e álcool isobutírico. A amostra 245 (Serra Gaúcha), que obteve a melhor aceitação, distinguiu-se das amostras 326 e 512 (Serra Gaúcha), de menor aceitação, pela alta concentração de acetato de etila, 1-butanol, 2-metil-1-butanol concomitantemente com o 3-metil-1-butanol, hexanoato de etila, 3-metil-1-pentanol, octanoato de etila e ácido hexanóico. Uma análise olfatométrica preliminar permitiu a detecção dos compostos voláteis odoríferos presentes na amostra de maior aceitação, além de estabelecer sua contribuição para o aroma total. Acetato de feniletila, furfural, hexanoato de etila, ácido hexanóico e butírico, além de um composto não identificado foram considerados importantes para o aroma do vinho estudado
Abstract: Despite the importance of flavour in determining the sensorial quality of wines, there are only few studies concerning the volatile composition of Brazilian wines. These few studies reported only major compounds, utilizing packed columns while other researchers described only the sensorial profile of the wines, without establishing any correlation of the data with other parameters. In the present study, 11 Cabernet Sauvignon red wines from main regions of the country were analysed: Rio Grande do Sul (Serra Gaúcha and Campanha); Santa Catarina (Rio do Peixe valley) and Pernambuco/Bahia (Rio São Francisco valley). Physical-chemical parameters were determined by classic analysis and the minerals content was determined by flame absorption and flame emission methods, after homogenization of 3 wine bottles. Nine selected and trained judges, utilizing Quantitative Descriptive Analysis, determined the samples¿ sensorial characteristics. They were evaluated in fiveplicates through 11 sessions. The acceptance test was realized with 87 consumers participation and data were interpreted utilizing Internal Preference Mapping (MDPREF). The volatile compounds were extracted in triplicates from each wine bottle and Total Analysis technique was used. A Lichrolut EN cartridge was utilized and elution with dichloromethane was performed, according to an already recognized in the literature methodology for volatile compounds analysis in wine. The volatile mixture of compounds was separated by high-resolution gas chromatography, utilizing two columns with different polarity phases. The identification of volatile compounds was realized by using mass spectrometer coupled to gas chromatography, besides comparison of Kovats experimental indexes with literature values and beyond that comparison between spectral mass data of the unknowns and those of the standards. A preliminary olfatometric test was realized using two selected and trained judges, who evaluated aroma of the eluted compounds of the highest preferred sample. Results of the physical-chemical and mineral analyses indicated that all samples were within the established legal limits. The amount of volatile acids was considered high, but such a fact is expected when Cabernet Sauvignon wines are evaluated. Potassium content of the samples was higher than already reported values in literature. The use of the MDPREF demonstrated that sample 245 was the highest preferred wine, characterized by a strong perception of the sweet, fruity and red fruit aroma descriptors. The northeast wines and sample 512 obtained the lowest acceptance among consumers. Thirty-nine volatile compounds were identified by GC-MS and Kovats Indexes in Brazilian wines by the first time, of which 13 were alcohols, 13 esters, 7 acids, 2 lactones, 2 terpenes, 3 carbonyl compounds and a phenolic compound. In spite of the great variation observed among the samples, 3-methyl butanol and 2-methyl butanol peaks were the most abundant compounds, followed by phenylethyl alcohol, ethyl lactate and isobutyric acid. The previous olfatometric test applied to the extract of the most preferred wine leaded to the detection of the odoriferous volatile compounds responsible for their acceptance while determining the contribution of those compounds to the global aroma. Hexanoic acid, furfural, butanoic acid and ethyl hexanoate were considered important contributors to the aroma of this preferred sample. ACP applied to physical-chemical and mineral content of the samples was not able to discriminate different samples according to their geographical origin
Doutorado
Doutor em Ciência de Alimentos

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Brlíková, Eliška. "Vliv přídavku tuzemských vín při výrobě vinných klobás." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2021. http://www.nusl.cz/ntk/nusl-449720.

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The aim of this diploma thesis was to determine the effect of the addition of several types of local wines in the production of wine sausages. Selected wine varieties were characterized using basic and modern analytical methods (liquid chromatography with a diode array detector) and the obtained results were compared with the results of sensory analysis.The sensory analysis was divided into two parts, the first evaluated six non-traditional wine varieties used in the production of wine sausages and the second part evaluated samples with the addition of the traditionally used wine variety Veltlínské zelené, but in three different volumes. Using the Statistica program, the data obtained from the sensory analysis were processed and the mutual correlation was evaluated. Using the gas chromatography method with a flame ionization detector the fatty acid content of a standard sample of wine sausage has been determined. Based on all the determined results, the best wine variety for the production of wine sausages was chosen, it was the blue grape variety André.

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Koenig, Lea. "Démarche taxonomique appliquée à la structuration hiérarchique d’un lexique aromatique et application à la caractérisation sensorielle des vins par une méthode HRATA." Thesis, Nantes, Ecole nationale vétérinaire, 2020. http://www.theses.fr/2020ONIR144F.

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La caractérisation aromatique des vins est une tâche complexe, même pour les évaluateurs expérimentés. Pour la faciliter, les termes aromatiques peuvent être regroupés par catégorie d’odeurs et présentés parfois sous forme de roues. Dans cette thèse, une nouvelle méthodologie, appelée Hierarchical-Rate-All-That-Apply (HRATA) est proposée. Celle-ci associe une structuration hiérarchique des attributs avec la méthodologie Rate-All-That-Apply (RATA) et est appliquée à la caractérisation aromatique de vins. Une première réflexion porte sur la structuration hiérarchique d’un lexique de termes aromatiques sur la base d’une expérimentation de tri libre. La représentation des proximités entre termes s'appuie sur la méthodologie des arbres additifs qui combinée à une stratégie de catégorisation permet de proposer une structuration taxonomique du lexique mis en œuvre. Une attention particulière est également portée sur l’influence de l’expertise dans la structuration d’un lexique aromatique du vin. La structuration hiérarchique est finalement intégrée lors de l’évaluation sensorielle au moyen d’une épreuve de notation de type RATA. Cette nouvelle méthode HRATA offre plus de liberté aux sujets car ils peuvent sélectionner les termes descriptifs à partir d'une grande variété d'attributs, généraux ou spécifiques selon leur sensibilité individuelle. Du point de vue statistique, les méthodes usuelles sont adaptées pour l’identification des attributs discriminants et la détermination d’une carte des produits. Du point de vue statistique, les méthodes usuelles sont adaptées pour l’identification des attributs discriminants et la détermination d’une carte des produits
The aromatic characterization of wines turns out to be a complex task, even for well-trained assessors. To gain ease, a common way consists in grouping terms into odor categories and organizing them by wheels. In this thesis, a new methodology, called Hierarchical-Rate-All-That-Apply (HRATA), is proposed. It combines a hierarchical structuration of the set of attributes together with Rate-All-That-Apply (RATA) notation. The HRATA methodology is then applied for the aromatic characterization of wines. In the first part, the structuration of a lexicon of aromatic terms is defined on the basis of a free sorting experiment. The representation of the proximities between terms is carried out by means of additive trees. An original partitioning technique is proposed, on the basis of an additive tree, which makes it possible to set up the taxonomic structuration of the lexicon. Particular attention is also paid to the influence of expertise in the structuration of an aromatic lexicon of wine. The hierarchical structure, thus obtained, is finally integrated into a sensory evaluation by means of a RATA rating. This new methodology HRATA provides a user-friendly characterization for subjects since they can rate descriptive terms from a wide variety of attributes, general or specific, depending on their individual sensitivity. From a statistical point of view, an adaptation of the usual techniques is carried out for the identification of discriminating attributes and the determination of a product map

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Silva, Vlademir Lenine Mendes da. "O efeito da marca na avaliação sensorial de um vinho." Master's thesis, Universidade de Évora, 2020. http://hdl.handle.net/10174/28086.

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Numa época em que o ambiente do marketing muda de uma semana para outra, importa conhecer a influência da marca na apreciação de um vinho, através da análise sensorial. O objetivo deste estudo foi o de avaliar o efeito da marca de um vinho, na preferência de um painel de consumidores comuns. Foram selecionados 32 provadores para avaliarem 6 vinhos tintos DOC e Regionais produzidos na região Alentejo, com PVP entre os 5 € e os 10 €. Os vinhos foram disponibilizados ao painel de provadores em dois diferentes momentos, avaliação em prova cega e avaliação com prova em que a marca estava visível. Os resultados obtidos mostram que os valores médios mais elevados, situam-se na prova com marca, em todas as variáveis, o que significa que os consumidores provadores são influenciados pela marca dos vinhos. A diferença na pontuação das amostras, após o conhecimento da marca, vem confirmar a tese de que a influência dos atributos extrínsecos é superior ao das caraterísticas sensoriais do vinho; The effect of branding on sensory evaluation of a wine Abstract: At a time when the marketing environment changes from week to week, it is important to know the influence of the brand on the appreciation of a wine through sensory analysis. The aim of this study was to evaluate the effect of a wine brand on the preference of a panel of ordinary consumers. 32 tasters were selected to evaluate 6 DOC and Regional red wines produced in the alentejo region, with PVP between 5 € and 10 €. The wines were made available to the tasting panel at two different times, blind tasting evaluation and matching visible tasting evaluation. The results show that the highest average values are in the branded tasting in all variables, which means that the tasters are influenced by the brand of the wines. The difference in sample points, after brand awareness, confirms the thesis that the influence of extrinsic attributes is greater than the sensory characteristics of wine.

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Rupio, José Alberto Mósca. "Importância dos estímulos do marketing na apreciação de um vinho." Master's thesis, Universidade de Évora, 2017. http://hdl.handle.net/10174/22816.

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A qualidade de um vinho apresenta múltiplas facetas e interpretações, sendo diferentemente percepcionada pelo consumidor comum consoante os seus hábitos de consumo e critérios fisiológicos, psicológicos e sociodemográficos. A análise sensorial é hoje utilizada como ferramenta de aferição do gosto e preferência do consumidor de vinho, possibilitando obter resultados válidos e representativos dos atributos mais valorizados pelo consumidor com recurso a painéis de provadores. Através da prova cega, reduzem-se as interferências externas à análise sensorial, permitindo obter uma avaliação isenta da influência das marcas ou de outros fatores distratores. O provador reage assim apenas à sua análise, sensibilidade e gosto pessoal, classificando o produto baseando-se em fatores exclusivamente intrínsecos e pela sua preferência hedónica. A marca é frequentemente considerada pelo consumidor como um dos atributos de qualidade no vinho. A montante da marca encontra-se o marketing, ferramenta de gestão responsável, entre muitos outros parâmetros, pela imagem de marca do vinho; Abstract: The quality of a wine has a lot of interpretations, being perceived by the common consumer in diferent ways, acording to his consumption habits, physiological, psychological and sociodemographic criteria. Sensory analysis, currently, it is also used as a measurement tool of taste and preference of wine consumer, giving the possibility to get valid and representative results for the most valorized attributes by consumer using tasting panels. Blind Tasting can reduce external interferences to sensory analysis, allowing an evaluation free from Brand Influence or other distraction factors. So the assessor responds only to his analysis, sensibility e personal taste, classifying the product only based on exclusively intrinsic factors, thus showing his hedonic preference. Brand is often considered by consumer one of the quality attributes in wine. Upstream the brand is marketing, a responsible management tool, among many other parameters, by the wine brand image.

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Serra, i. Cayuela Arnau. "Estudi de paràmetres que determinen la qualitat dels vins escumosos i la seva relació amb l'enfosquiment." Doctoral thesis, Universitat de Barcelona, 2014. http://hdl.handle.net/10803/145036.

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Segons estimació del Consell Regulador de l'any 2012, es van vendre 243 milions d'ampolles de vins escumosos amb denominació d'origen Cava, havent-hi registrats 253 cellers elaboradors de Cava i 163 empreses elaboradores del vi base. Per tant, és un sector econòmic important tant a Catalunya com en altres països, el qual vol oferir el millor producte als consumidors. La indústria elaboradora de vins escumosos considera important tenir paràmetres objectius que permetin estandarditzar la qualitat dels seus productes, i així poder garantir la millor qualitat d'aquests. L'aspecte visual és la primera característica que notem i que pot delectar o generar rebuig, podent influir en la percepció de l'aroma i/o el gust. L’estabilitat del color d'aquests vins en el procés d’elaboració, així com durant la distribució i l’emmagatzematge, és un aspecte de gran interès per les bodegues. El color dels vins escumosos acostuma a atribuir-se als compostos fenòlics procedents del raïm, tot i que hi ha altres substàncies en el medi que també poden contribuir en el procés de l'enfosquiment. Per altre banda, durant la rima les mares de segona fermentació poden alliberar o adsorbir compostos que poden alterar la qualitat visual dels vins, i per tant influir en el fenomen de l'enfosquiment. L’objectiu principal d’aquesta tesi Doctoral és avaluar el paper de les mares sobre el fenomen de l'enfosquiment i els compostos relacionats, així com trobar marcadors químics relacionats amb l'enfosquiment per crear models matemàtics per poder predir el període òptim de consum dels vins escumosos. Per a assolir aquest objectiu es van dissenyar dos mostrejos. Un per conèixer l'efecte de les mares de segona fermentació del Cava sobre l'enfosquiment i els compostos relacionats i l'altre per generar models matemàtics que permetin predir el temps màxim en el vi conservarà les seves propietats òptimes segons les condicions de conservació. En el primer, es va procedir a fer un estudi paral·lel amb dos series de vins comparant el període de rima i el mateix temps de vida comercial conservat en les mateixes condicions de celler. En el segon, es va realitzar un mostreig amb sis series de vins comercials, durant més de dos anys, conservats a diferents temperatures reals d'emmagatzematge (nevera, celler i ambient). No s'ha observat que les mares tinguin un paper destacat en la cinètica de formació de l'enfosquiment. Per altra banda, s'ha identificat el 5-HMF en el Cava i s'ha avaluat com a marcador de qualitat relacionat amb l'enfosquiment. En aquest sentit, aquest compost augmenta linealment amb el temps en el rang de temperatures estudiat. S'ha observat que posseïx bones característiques per ser emprat com a marcador de temps-temperatura, millors que la del clàssic paràmetre A420 i els compostos fenòlics. S'ha estudiat la cinètica de formació del 5-HMF, i a partir dels paràmetres cinètics s'han generat models matemàtics que permeten predir el temps de vida en el que el vi conserva les seves òptimes propietats. Aquests models permetran a les bodegues elaboradores de vins escumosos saber quan de temps els seus vins conservaran les propietats òptimes, així com disposar d'una eina útil per saber com han estat conservats els vins en cas de reclamació.
The sparkling wine wineries consider important to have parameters that allow standardizing the quality of their products, so they can guarantee the best quality of their wines. The appearance is the first characteristic we notice and can generate delight or rejection, and also it can influence the perception of smell and/or taste. The color stability of these wines in the process, as well as during distribution and storage, is something of great interest for the wineries . The color of sparkling wines is usually attributed to phenolic compounds from the grape, although there are other substances in the environment that can also contribute to the browning process. On the other hand, during the second fermentation the lees can release or adsorb compounds that may alter the visual quality of the wines, and thus have influence to the browning phenomenon. The main objective of this thesis is to evaluate the role of the lees on the phenomenon of browning and related compounds, as well as find chemical markers related to the browning in order to create mathematical models to predict the optimum period consumption sparkling wines. It has not been observed that lees have a role in the kinetics of formation of browning. Furthermore, 5-HMF has been identified in Cava and also it has been evaluated as a marker of quality related to browning. In this sense, this compound increases linearly with time in the temperature range studied. It has been observed that possesses good characteristics to be used as a marker as time-temperature parameter, with better properties than the classic A420 and phenolic compounds. We have studied the kinetics of formation of 5-HMF, and from these kinetic parameters were generated mathematical models that allow predicting the lifetime which the wine retains its optimum properties. These models allow sparkling wine producers to know how long their wines will retain their optimum properties and also provide a useful tool to see how the wines have been preserved in case of complaint.
Según estimación del Consejo Regulador del año 2012, se vendieron 243 millones de botellas de vinos espumosos con denominación de origen Cava, habiendo registradas 253 bodegas elaboradoras de Cava y 163 empresas elaboradoras del vino base. Por tanto, es un sector económico importante tanto en Catalunya como en otros países. La industria elaboradora de vinos espumosos quiere ofrecer el mejor producto a los consumidores así que considera importante tener parámetros objetivos que permitan estandarizar la calidad de sus productos. El aspecto visual es la primera característica que notamos y que puede deleitar o generar rechazo, pudiendo influir en la percepción del aroma y/o sabor. La estabilidad del color de estos vinos en el proceso de elaboración, así como durante la distribución y el almacenamiento, es un aspecto de gran interés para las bodegas. El color de los vinos espumosos suele atribuirse a los compuestos fenólicos procedentes de la uva, aunque hay otras sustancias en el medio que también pueden contribuir en el proceso del oscurecimiento . Por otro lado, durante la rima las lías de segunda fermentación pueden liberar o adsorber compuestos que pueden alterar la calidad visual de los vinos, y por tanto influir en el fenómeno del oscurecimiento . El objetivo principal de esta tesis doctoral es evaluar el papel de las lías sobre el fenómeno del oscurecimiento y los compuestos relacionados, así como encontrar marcadores químicos relacionados con el oscurecimiento para crear modelos matemáticos para predecir el periodo óptimo de consumo los vinos espumosos. Para lograr este objetivo se diseñaron dos muestreos: Uno para conocer el efecto de las lías de segunda fermentación del Cava sobre el pardeamiento y los compuestos relacionados y el otro para generar modelos matemáticos que permitan predecir el tiempo máximo en el vino conservará sus propiedades óptimas según las condiciones de conservación. En el primero, se procedió a realizar un estudio paralelo con dos series de vinos comparando el período de rima y el mismo tiempo de vida comercial conservado en las mismas condiciones de bodega . En el segundo , se realizó un muestreo con seis series de vinos comerciales, durante más de dos años, conservados a diferentes temperaturas reales de almacenamiento (nevera, bodega y ambiente ). No se ha observado que las lías tengan un papel destacado en la cinética de formación del pardeamiento. Por otra lado, se ha identificado el 5- HMF en el Cava y se ha evaluado como marcador de calidad relacionado con el pardeamiento. En este sentido, este compuesto aumenta linealmente con el tiempo en el rango de temperaturas estudiado. Se ha observado que posee buenas características para ser utilizado como marcador de tiempo- temperatura, mejores que la del clásico parámetro A420 y los compuestos fenólicos. Se ha estudiado la cinética de formación del 5-HMF, y a partir de los parámetros cinéticos se han generado modelos matemáticos que permiten predecir el tiempo de vida en el que el vino conserva sus óptimas propiedades. Estos modelos permitirán a las bodegas elaboradoras de vinos espumosos saber cuánto tiempo sus vinos conservarán las propiedades óptimas, así como disponer de una herramienta útil para saber cómo han sido conservados los vinos en caso de reclamación.

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Meneguzzo, Júlio. "Caracterização físico-química e sensorial dos vinhos espumantes da serra gaúcha." reponame:Repositório Institucional da UCS, 2010. https://repositorio.ucs.br/handle/11338/610.

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A influência da cultivar e da época de colheita na composição físico-química e na qualidade sensorial dos espumantes da Serra Gaúcha, Rio Grande do Sul, elaborados pelo método Champenoise nas safras 2006 e 2007, foi avaliada. As cultivares utilizadas foram Riesling Itálico, Chardonnay e Pinot Noir. As uvas foram colhidas em duas épocas distintas: uma referente ao ponto de colheita definido como ideal (época 1) e outra oito dias após (época 2). Os mostos, os vinhos base e espumantes foram analisados quanto à composição básica conforme a metodologia oficial brasileira. Além disso, nos vinhos base e espumantes foram analisados os elementos minerais e compostos aromáticos, através de absorção atômica e cromatografia gasosa, respectivamente. Os espumantes foram avaliados sensorialmente, por uma equipe de degustadores qualificados. Os resultados das análises clássicas dos mostos e vinhos base diferenciaram cultivares e épocas de colheita, nas duas safras estudadas. O mosto de Chardonnay apresentou maior valor de grau º Brix e de álcool potencial. O Pinot Noir se diferenciou pela acidez mais elevada, enquanto que o Riesling Itálico apresentou menores grau Brix e acidez total. Os mostos das uvas colhidas na segunda época apresentaram maiores teores de açúcar, álcool potencial, pH e relação brix/acidez total, e menor acidez. Nos vinhos base, as cultivares Chardonnay e Riesling Itálico apresentaram, respectivamente, maior e menor teor alcoólico e os vinhos das uvas de colheita mais tardia apresentaram menor acidez total. Entretanto, nos vinhos espumantes as análises clássicas não apresentaram diferenças significativas em relação às cultivares e épocas de colheita. Entre os elementos minerais dos vinhos base e dos espumantes correspondentes, o Zn foi único elemento que apresentou diferença significativa entre as cultivares sendo que os vinhos Chardonnay obtiveram os maiores teores. Os vinhos base provenientes das uvas com maior grau de maturação apresentaram, independente da cultivar, maiores níveis de K, Ca, Mg, Mn, Fe, Rb, Li e P e concentrações mais baixas em Cu e Zn. Quanto aos compostos voláteis, maiores quantidades de 2-fenil etanol e dietil succinato diferenciaram os vinhos da cultivar Chardonnay e maiores concentrações de hexanoato de etila e de acetato de isoamila diferenciaram os vinhos da cultivar Riesling Itálico. Já os vinhos Pinot Noir apresentaram teores de 2-metil-1-propanol e 2-metil-1-butanol significativamente superiores às outras variedades. Os vinhos obtidos de uvas colhidas na segunda época apresentaram menores teores de ácido butírico, diferenciando as duas épocas de colheita. Quanto à avaliação sensorial, a variedade Riesling Itálico apresentou maiores notas florais e a Chardonnay maior nota no frutado, tanto no aspecto olfativo quanto no gustativo. Já a Pinot Noir, maior nota vegetal, levedura e pão tostado. Na avaliação final os degustadores não fizeram distinção entre os espumantes Pinot Noir e os Chardonnay, preferindo estes aos de Riesling Itálico, nas duas safras estudadas. Na safra 2007 os degustadores preferiram os espumantes das uvas da primeira época de colheita, enquanto na safra 2006 não foi observada diferença entre as épocas de colheita. O presente trabalho contribuiu para a identificação dos principais constituintes e descritores que determinam a distinção e a tipicidade dos vinhos espumantes da Serra Gaúcha.
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The influence of cultivar and harvest date on physico chemical composition and sensory quality of sparkling wines from Serra Gaúcha, Rio Grande do Sul, produced by the Champenoise method for crop years 2006 and 2007 were evaluated. The cultivars were Riesling Italico, Chardonnay and Pinot Noir. The grapes were harvested at two different times: one related to the harvesting point defined as ideal (season 1) and another eight days after (time 2). Musts, base wines and sparkling wines were analyzed based on the basic composition as the official Brazilian methodology. In addition, the base wines and sparkling wines were analysed the mineral elements were analyzed and aromatic compounds by atomic absorption and gas chromatography, respectively. Sparkling wines have been evaluated by a team of qualified tasters. The results of the classical analysis of musts and base wines differentiated cultivars and harvest times in the two seasons studied. The Chardonnay must showed higher brix value and potential alcohol. The Pinot Noir has distinguished by higher acidity, while the Riesling Italico had lower Brix and total acidity. The musts of grapes harvested in the second season showed higher levels of sugar, potential alcohol, pH and the realation Brix/total acidity and lower acidity. In the base wine, the varieties Chardonnay and Riesling Itálico were respectively higher and lower alcohol content and wine grapes harvested later showed lower acidity. However, in the sparkling wines the classic analysis showed no significant differences in different cultivars and harvest times. Among the mineral elements of the base wines and sparkling wines corresponding Zn was the only element that showed a significant difference among cultivars is that Chardonnay wines had the highest levels. The base wine from grapes with a higher degree of maturity showed, regardless of cultivar, higher levels of K, Ca, Mg, Mn, Fe, Rb, Li and P and lower concentrations of Cu and Zn. As for the volatile compounds, larger amounts of 2-phenyl ethanol and diethyl succinate differentiated the wines of the cultivar Chardonnay, and higher concentrations of ethyl hexanoate and isoamyl acetate differentiated the wines of the cultivar Riesling Italico. Already Pinot Noir wines showed levels of 2-methyl-1-propanol and 2-methyl-1-butanol significantly higher than other varieties. The wines made from grapes harvested in the second period had lower levels of butyric acid, differentiating the two harvest seasons. As for the sensory evaluation, the variety Riesling Itálico showed higher floral notes and the Chardonnay with highest score on fruity in both the olfactory and the gustatory aspect. As for the Pinot Noir, highest notes aromatic for vegetable, yeast and toasted bread. In the final evaluation the panelists made no distinction between the sparkling wines Pinot Noir and Chardonnay, preferring these to Riesling Itálico, in the two harvests studied. In the season 2007 the tasters preferred the sparkling wines from the grapes of the first harvest season, while the harvest in 2006 there was no difference between harvest seasons. This work helped identify the main components and characteristics that determine the distinguish and tipicity of sparkling wines from the Serra Gaúcha.

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Silva, Maria Adélaide. "Effet de l’obturateur sur l’évolution de la qualité sensorielle du vin." Thesis, Bordeaux 2, 2011. http://www.theses.fr/2011BOR21902/document.

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L’évolution des vins lors de la conservation en bouteille est un processus lent et complexe où les obturateurs jouent un rôle fondamental, conséquence directe de leur perméabilité à l’oxygène mais aussi des interactions physico-chimiques avec les constituants du vin.Dans un premier temps nous avons étudié l’effet de la conservation en bouteille des vins de Sauvignon blanc après 24 mois d’embouteillage. Dans cette étude, la combinaison des conditions de mise en bouteille et des taux de transfert d'oxygène à travers les bouchons ont eu un effet significatif sur le développement du Sauvignon après l'embouteillage. Les vins fermés hermétiquement en bouteille « ampoule » ou avec des obturateurs à très faible taux de transfert d'oxygène comme les capsules à vis, présentent les plus fortes concentrations en dioxyde de soufre, en acide ascorbique, et en thiols variétaux, mais aussi des niveaux élevés de sulfure d’hydrogène (H2S), qui ont complètement masqué le fruité des vins, par rapport au caractère réduit dominant. Les plus fortes concentrations en 3-sulfanyl-hexanol (3SH) ont été trouvées pour les vins présents dans les bouteilles « ampoules » suivi des bouteilles scellées avec des bouchons à vis saran et des bouchons agglomérés. Les teneurs les plus faibles en 3SH ont été trouvées pour les bouteilles scellées avec des bouchons synthétiques (Nomacorc classic). Le développement du vin à partir de deux mois semble être plutôt lié aux propriétés de perméabilité des différents obturateurs utilisés.Dans un deuxième temps nous avons voulu étudier l’incidence de sept types d’obturateurs (bouchon en liège : naturel, naturel colmaté, microaggloméré, ciré, bouchons synthétiques, capsules à vis : saran et saranex) sur des marqueurs chimiques d’oxydation et de réduction, sur les teneurs en oxygène du vin, ainsi que sur la composition phénolique et aromatique des vins issus de cinq cépages (Merlot, Cabernet Sauvignon, Syrah, Sauvignon blanc et Riesling). Nous avons vérifié que la concentration d’oxygène dans l’espace de tête après embouteillage varie selon le type d’obturateurs, celle-ci peut être jusqu’à trois fois plus importante dans le cas des capsules à vis. Les teneurs en oxygène apportées lors de la mise en bouteille pourraient être responsables de l’absence de discriminations des paramètres chimiques entre les différentes modalités d’obturateurs, après 24 mois de conservation en bouteille. Nous avons mis en évidence une évolution de la composition des vins, avec une diminution importante des concentrations de certains composés (certaines anthocyanes telles que la malvidine et la cyanidine-3-O-glucoside ont diminuées de 60%, des flavanols monomères et dimères présentent des diminutions de l’ordre de 20%) pour les cépages rouges et une augmentation pour d’autres composés, comme l’H2S ou la 3-méthyl-2,4-nonanedione (MND, augmentation de 10%) ou le 1,1,6-triméthyl-1,2-dihydronaphtalène (TDN), dans le cas du Riesling; il est intéressant de remarquer que l’évolution de ce dernier semble être dépendante du type de bouchon, alors que les taux d’autres composés comme le sulfure de diméthyl (DMS) ne semblent pas être affectés par l’obturateur.L’étude des interactions entre les différents obturateurs et les composés soufrés du vin, tel que le sulfure d’hydrogène, responsables des odeurs désagréables couramment appelés « odeurs de réduction » a été réalisée. Nous constatons pour la première fois l’existence d’une sorption/ « scalping » de 75% d’ H2S ou de DMS en solution, après 25 jours de macération par les bouchons en liège. Nous montrons que certains des obturateurs étudiés peuvent sorber/scalper ces molécules, en milieu modèle hydroalcoolique, ouvrant ainsi les portes à des futures expérimentations portant sur l’obturateur en tant que constituant actif d’un emballage jouant un rôle dans la composition, l’évolution et la perception sensorielle du vin
Wine post-bottling evolution is a slow and complex process where the closures play a fundamental role as a consequence of their permeability to oxygen and of physicochemical interactions with the constituents of wine.Initially we studied the effect of conservation in bottle of Sauvignon Blanc wines after 24 months of bottling. In this study, the combination of the bottling conditions and rates of oxygen transfer through closures have had a significant effect on the development of Sauvignon after bottling. Wine stored in an airtight bottle or under closures allowing very low oxygen transfer, such as screw caps, had the highest concentrations of sulfur dioxide, ascorbic acid, and varietal thiols; these wines also had the highest levels of hydrogen sulfide (H2S) with dominant reduced off-flavours masking their fruity character. The highest concentrations of 3-sulfanyl-hexanol (3SH) were found in wines contained in the airtight bottles followed by those sealed with screw caps saran and agglomerated corks. The lowest levels were found in bottles sealed with synthetic corks (Nomacorc classic). The development of wine after two months seems to be related to the permeability properties of the different plugs used.Secondly, we studied the impact of seven types of closures (natural cork, colmated cork, microagglomerated cork, natural cork with wax, synthetic, screw caps: saran and saranex) on oxidation and reduction chemical markers, on oxygen contents, as well as phenolic and aromatic composition of wines from five grape varieties (Merlot, Cabernet Sauvignon, Shiraz, Sauvignon Blanc and Riesling). We observed that the oxygen concentration in the headspace after bottling varies with the type of closure, being up to three times higher in the case of screw caps. The oxygen introduced during bottling may be responsible for the lack of overall discrimination between chemical parameters of the different modalities of closures after 24 months of storage. We have demonstrated a change in the composition of wines, with a significant decrease in concentrations of certain compounds (anthocyanins like malvidin and cyanidin-3-O-glucoside were reduced by 60%, flavanol monomers and dimers decreased about 20%) for red grape varieties and an increase of other compounds such as H2S or 3-methyl-2,4-nonanedione (MND), with an increase of 10% or 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN), in the case of Riesling. The evolution of the latter appears to be dependent on the type of closure, while rates of other compounds such as dimethyl sulfide (DMS) remain unaffected.The interactions between different closures and sulfur compounds, such as hydrogen sulfide, responsible for the “reduction” off-flavours in wine were studied. We see for the first time the existence of a sorption/scalping, by cork stoppers, of 75% of H2S or DMS in solution, after 25 days of maceration. We show that some of the closures studied can sorb/scalp these molecules in wine-like media. This may have an impact on the composition, the development and sensory perception of wine, opening the door to future experiments regarding closures as active packaging constituents

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