Добірка наукової літератури з теми "Red wine aroma"

Volatile compounds are responsible for driving the aroma of wine. Because of their low perception thresholds, norisoprenoids may play an important role in wine aroma. Studies have shown that β-damascenone may act as an aroma enhancing compound. However, the direct impact on wine aroma is unclear. Our study examined the direct impact of β-ionone and β-damascenone on the aroma sensory perception of Pinot noir wines. Triangle tests were used to determine if assessors could distinguish between wines with varying concentrations of β-ionone and β-damascenone in three different Pinot noir wine matrixes. Descriptive analysis was performed on these treatments, perceived as different in triangle tests. Results show that β-ionone acts as a significant contributor to aromas in Pinot noir wine, as individuals could differentiate both the low and high concentration wines from the control. How β-ionone impacted wine aroma depends on the wine matrix, as different aroma descriptors were affected based on the model wine used, resulting in floral, red berry or dark berry aromas. The effect of β-damascenone on Pinot noir aroma was less clear, as perception seems to be heavily influenced by wine matrix composition. This study contributes to our understanding of the complex chemical causation of fruity aromas in Pinot noir wine.

Hexi Corridor is an excellent region for high-quality wines in China, but the characteristic and style of red wine from this region is unclear. To elucidate the regional style of red wines from Hexi Corridor, the aroma properties of red wines made from 16 different varieties/clones of grapes were comprehensively analyzed using HS-SPME-GC-MS, sensory evaluation, odor activity value method, and partial least squares regression analyses. We identified 52 aroma compounds and found that floral and black berry provided a good reference for shaping red wine style and selecting related varieties in Hexi Corridor region. Ethyl caproate, (Z)-3-hexen-1-ol, ethyl 9-decenoate, and hexyl alcohol, which were the characteristic aroma substances of Hexi Corridor red wines, had positive effects on the floral aroma of Merlot, Cabernet Sauvignon, Pinot Noir, and Malbec wines. Hexyl alcohol and (Z)-3-hexen-1-ol also contributed to the black berry and spice aromas, while isobutyl acetate opposed the expression of these aromas of Malbec and Cabernet Franc wines. These results showed that the sensory characteristics of floral and black berry are of vital significance in shaping the red wine style of Hexi Corridor, among which ethyl caproate, (Z)-3-hexen-1-ol, ethyl 9-decenoate, and hexyl alcohol are important contributors.

Wine yeast starter cultures differ in their ability to release aroma-enhancing metabolites associated with typical varietal wines. Therefore, this study investigated an indigenous Saccharomyces cerevisiae isolated from Paarl regional Shiraz grapes for the release of, amongst others, volatile thiols (aroma compounds traditionally associated with white cultivars, especially Sauvignon blanc) during the 2016 and 2017 vintages using Shiraz grape must. Chemical analyses of final wines showed that the indigenous strain i.e., NI6 produced Shiraz wines lower volatile acidity (VA) and acetic acid concentrations than wines produced with reference strains i.e., WE372 and MERIT, respectively. This was further supported by descriptive sensory evaluations of wines, as NI6 wines had typical Shiraz varietal aromas and flavours, i.e.,“berry”, “jammy”, “smoky” and “spicy and peppery”. This yeast strain also produced wines with more 3-mercapto-1-hexanol (3MH), a volatile thiol that imparts black currant aromas in red wines, than both red wine reference strains in 2016. Both red wine reference strains, however, produced red wines with higher ester compounds (imparts “fruity” aroma) concentrations than strain NI6. Nonetheless, the ability of NI6 to consistently release volatile thiols during both vintages is advantageous for Shiraz wine typicity. Overall, this study showed that wines with a positive correlation with black and/or fruits aromas and flavours also had volatile thiol levels above its sensory detection thresholds, which indicates that ester compounds are not solely responsible for Shiraz wine fruity aromas and flavours as was traditionally reported.

Wine aroma is the result of complex interactions between volatile compounds and non-volatile ones and individual perception phenomenon. In this work, an aroma network approach, that links volatile composition (chromatographic data) with its corresponding aroma descriptors was used to explain the wine aroma properties. This concept was applied to six monovarietal wines from Bairrada Appellation (Portugal) and used as a case study. A comprehensive determination of the wines’ volatile composition was done (71 variables, i.e., volatile components), establishing a workflow that combines extraction techniques and gas chromatographic analysis. Then, a bipartite network-based approach consisting of two different nodes was built, one with 19 aroma descriptors, and the other with the corresponding volatile compound(s). To construct the aroma networks, the odor active values were calculated for each determined compound and combined with the bipartite network. Finally, the aroma network of each wine was compared with sensory descriptive analysis. The analysis of the specific aroma network of each wine revealed that Sauvignon Blanc and Arinto white wines present higher fruity (esters) and sweet notes (esters and C13 norisoprenoids) than Bical wine. Sauvignon Blanc also exhibits higher toasted aromas (thiols) while Arinto and Bical wines exhibit higher flowery (C13 norisoprenoids) and herbaceous notes (thiols), respectively. For red wines, sweet fruit aromas are the most abundant, especially for Touriga Nacional. Castelão and Touriga Nacional wines also present toasted aromas (thiols). Baga and Castelão wines also exhibit fusel/alcohol notes (alcohols). The proposed approach establishes a chemical aroma fingerprint (aroma ID) for each type of wine, which may be further used to estimate wine aroma characteristics by projection of the volatile composition on the aroma network.

During the alcoholic fermentation of grape sugars, wine yeast produces a range of secondary metabolites that play a critical role in the aroma profile of wines. One of the most impactful yeast-modified compound families, particularly in white wines, are the ‘fruity’ polyfunctional thiols, which include 3-mercaptohexan-1-ol (3-MH) and 4-mercapto-4-methylpentan-2-one (4-MMP). While the formation and stylistic contribution of these thiols have been extensively researched in white wines, little is known about the conditions leading to their formation in red wines. In this study, we explored the ability of yeast strains to modulate the release of these aroma compounds during the fermentation of two red musts. In laboratory-scale Pinot Noir fermentations, the formation of 3-MH strongly correlated with yeast β-lyase activity, particularly with the presence of certain genotypes of the flavour-releasing gene IRC7. Subsequent production of Grenache wine at the pilot scale, with detailed compositional and sensory analysis, was undertaken to confirm laboratory-scale observations. A commercial wine strain used for expressing ‘fruity’ thiols in Sauvignon Blanc was shown to produce wines that exhibited more intense red fruit aromas. These results reveal an opportunity for winemakers to shape red wine aroma and flavour by using yeasts that might typically be considered for white wine production.

<p style="text-align: justify;"><strong>Aim</strong>: The goal of this study was to evaluate the impact of dimethyl sulfide (DMS) on the fruity aroma of a complex mixture containing 12 red wine esters.</p><p style="text-align: justify;"><strong>Methods and results</strong>: Aromatic reconstitutions were prepared using pure commercial esters and acetates at the average concentrations found in red wines, as well as several concentrations of DMS. The olfactory thresholds of DMS in such matrices were: 1.74 µg/L in dilute alcohol solution, 2.80 µg/L in fruity aromatic reconstitution (12 esters) in dilute alcohol solution, and 3.67 µg/L in fruity aromatic reconstitution in dearomatized red wine. The "olfactory threshold" of the fruity pool, consisting of the 12 esters, was calculated in two different matrices: dilute alcohol solution and dilute alcohol solution supplemented with 5 µg/L DMS. The presence of DMS in the mixture led to significantly decreased of the "olfactory threshold" of the fruity pool, highlighting its effect in increasing overall aroma intensity. Sensory profiles were then evaluated to investigate the qualitative impact of DMS on fruity aroma perception.</p><p style="text-align: justify;"><strong>Conclusions</strong>: These results confirmed the sensory importance of DMS, suggesting that it was an active contributor to the black-berry fruit nuances in the fruity matrix studied. This compound participated, both quantitatively and qualitatively, in modulating black-berry fruit aroma and, more specifically, in enhancing blackcurrant aroma.</p><p style="text-align: justify;"><strong>Significance and impact of the study</strong>: Studies investigating fruity aromas in red wines over the past decade have discussed the implication of DMS in fruity aroma expression. Although DMS does not present fruity aromas, this study clearly shows its indirect impact on fruity aroma expression, via particular perceptive interactions, in fruity model mixture.</p>

HSSPME-GC/MS method was used to investigate the volatile compounds responsible for varietal character in the aroma of wine distillates made from 16 different red wine grape cultivars: Andre, Blue Frankish, Merlot, Cabernet Moravia, Rubinet, Pinot Noir, Ariana, Alibernet, Laurot, Dornfelder, Blauer Portugieser, Agni, Neronet, Zweigeltrebe, Cabernet Sauvignon, and Domina. The grapes were all grown in the same vineyard in South Moravia, an important viticultural region in the south of the Czech Republic bordering Austria. The isometric log-ratio transformation was used to compute variances prior to statistical analysis, and a compositional biplot was used to interpret the data and identify the main chemical markers. A comparison of the key terpenoids present in the aroma profiles indicated that these were consistent with the known relationships between the cultivars based on their parentage. There were similarities in the terpenoid elements of the aroma profiles of Blue Frankish and its relatives Andre, Laurot, Agni, and Zweigeltrebe, which are dominated by (Z)-linalool oxide, linalool, isoborneol, terpinen-4-ol and &alpha;-terpineol. On the other hand, the aroma profiles of Pinot Noir, Blauer Portugieser, Cabernet Sauvignon and their related hybrids are dominated by o-cymene, limonene, (E)-sabinyl acetate, and (E)-calamenene. &nbsp;

During fermentation or ageing of wines, oak wood is commonly used in form of barrels, casks or derived oak products (chips, winewoods, tankstaves, among others). It is well known that aroma, structure, astringency, bitterness, aromatic persistence and colour may change as a result of wine‒wood contact. A full-scale experimentation was performed under different oak ageing conditions in order to evaluate colour, phenolic, aromatic and sensory differences among final red wines (9‒months ageing). Oenological parameters and wine colour were not impacted by ageing modality. At the end of ageing, no differences were found in total phenolic and tannin contents. Regardless of the ageing modality, total content and profile of fruity volatiles were globally maintained with regard to control (≥ 86 %). In contrast, the higher the surface of wine‒wood contact per unit of wine volume, the greater the extraction of woody aromas. Thus, barrels led to wines with the highest level of woody aromas (515‒864 µg/L), followed by cask modalities (430‒470 µg/L). From a sensory point of view, descriptors highlighting the woody character of wine (vanilla, spicy) were enhanced in all oak‒aged wines when compared to control. However, our results indicate that a masking effect of fruity aroma by oak wood did not occur, since all modalities were perceived as fruity as the control. Thus, each oak ageing modality may lead to wines with a different woody character, without no impact on fruity perception, allowing wineries to achieve the targeted aromatic profile, good structure and just the right balance between fruity and woody aromas.

Wine polyphenols (PPhs) and volatile organic compounds (VOCs) are responsible for two of the main sensory characteristics in defining the complexity and quality of red wines: astringency and aroma. Wine VOCs’ volatility and solubility are strongly influenced by the matrix composition, including the interactions with PPhs. To date, these interactions have not been deeply studied, although the topic is of great interest in oenology. This article reviews the available knowledge on the main physicochemical and sensory effects of polyphenols on the release and perception of wine aromas in orthonasal and retronasal conditions. It describes the molecular insights and the phenomena that can modify VOCs behavior, according to the different chemical classes. It introduces the possible impact of saliva on aroma release and perception through the modulation of polyphenols–aroma compounds interactions. Limitations and possible gaps to overcome are presented together with updated approaches used to investigate those interactions and their effects, as well as future perspectives on the subject.

“Portugizac Mlado vino” is a local red wine with Protected designation of origin and Traditional term, and it is usually consumed very soon after alcoholic fermentation as a young wine. The maturation and aging of the wine affect the aroma composition, which is generally not pronounced and specific in the case of most red wines, but, as a sensory property, it is important for the perception of quality and consumer choice. The objective of this work was to analyze the most important aroma compounds of esters and higher alcohols, with the unpleasant volatile phenols too, in “Portugizac” wines, related to aging. The 9 young wines “Portugizac”, PDO “Plešivica” were analyzed after 3 and after 15 months of bottle storage at 16 ºC. Ethyl esters of butanoic and hexanoic acid along with isoamyl acetate are considered to be the most important esters in the fruity aroma of wine, and their concentrations in all analyzed “Portugizac” young wine samples were higher than their perception thresholds. The concentration of ethyl acetate was in the range 30-123 mg/L. The concentrations of ethyl esters of octanoic and decanoic acid, as well as 2-phenyl ethyl acetate and diethyl succinate in all analyzed wines, were lower than their perception thresholds. The concentrations of higher alcohols were much higher than their perception threshold. Bottle storage significantly affected the concentrations of analyzed compounds; after 15 months, the concentrations of acetate and ethyl esters (except ethyl acetate and diethyl succinate), as well as terpene (linalool), decreased, while higher alcohols and ethyl phenols slightly increased if compared to three months. In general, the compounds responsible for the desired fresh, fruity aroma tones were altered in an undesirable manner, while, undesirable compounds of 4-ethyl-phenol and 4-ethyl-quaiacol, which were not present in young wines, were detected in aged wines. It can be concluded that the bottle aging affects the aroma profile, undesirable changes were more pronounced than positive ones and therefore the consumption of young wine “Portugizac” might be more sensory attractive.

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.

La plupart des composés volatils connus et impliqués dans les mécanismes de l’expression fruitée des vins rouges sont présents à des teneurs inférieures ou proches de leurs seuils de perception individuels. Compte tenu de phénomènes d’interactions perceptives entre eux, il est très complexe de déterminer leur impact réel sur l’arôme du vin. Au vu des difficultés rencontrées pour reconstituer fidèlement l’arôme des vins à partir uniquement de composés purs, nous avons développé une méthodologie permettant d’aborder cette reconstitution aromatique à partir de fractions issues du vin lui-même, afin de pouvoir évaluer l’importance relative de ces différentes fractions aromatiques vis-à-vis de l’arôme global du vin. Grâce à l’analyse sensorielle, et en s’attachant à quelques descripteurs particuliers, nous avons pu mettre en évidence, quelques interactions perceptives particulières comme des effets de contributions marquées ou de masquage. La caractérisation des composés présents dans les fractions concernées et à l’origine de ces effets notables a été mise en œuvre. Nos résultats soulignent le rôle indirect du 2-hydroxy-4-méthylpentanoate d’éthyle, un ester éthylique élué dans la fraction à l’origine d’une contribution marquée aux notes de fruits noirs frais qui, en provoquant la diminution du "seuil de perception" du pool fruité des vins rouges et l’augmentation de l’intensité de leurs notes de fruits noirs et de fruits frais, agit comme un exhausteur naturel de ces notes fruitées. Nous sommes aussi parvenus à mettre en évidence, le rôle direct du diacétyle, mais aussi le rôle indirect de l’acétoïne, de l’acide acétique et de la γ-butyrolactone, malgré leurs concentrations infraliminaires, sur la diminution de l’intensité globale et l’intensité du caractère de fruits frais. Ces résultats soulignent leur fort caractère, seuls ou en mélanges, de "réducteurs" de l’intensité de ces notes, et ce, même à des concentrations infraliminaires. Enfin, le comportement particulier, au sein d’un mélange fruité, du 3-hydroxybutanoate d’éthyle, de l’acétate de 2-méthylpropyle, du propanoate d’éthyle et de l’acétate de butyle, présents à des concentrations infraliminaires a été mis en évidence. La présence en mélange des deux premiers provoque la baisse notable du "seuil de perception" du pool fruité et celle des trois derniers augmente l’intensité des notes de fruits frais et fruits noirs traduisant l’effet exhausteur d’arômes dû à ces composés, effet comparable de celui du 2-hydroxy-4-méthylpentanoate d’éthyle qui présente quelques analogies structurales avec ces composés
Most of volatiles involved in red wines’ fruity expression are present at levels below or close to their individual perception thresholds. Given the existence of perceptive interactions between them, it is very difficult to determine their real impact on wine aroma. Rather than assessing the olfactive behavior of mixtures prepared from pure products, the main goal of this work was to highlight and study the impact of perceptive interactions on wine fruity aroma expression using various aromatic reconstitutions prepared from wine fractions. Sensory profile analyses identified significant differences among aromatic reconstitutions for the intensity of some descriptors, as particular "additive" or "masking" effects. The composition of the involved fractions was then studied by instrumental methods. The final target was to investigate the impact of fraction components on fruity aroma by preparing aromatic reconstitutions and using sensory reconstitution tests, to assess the role of these compounds on the perceptive interactions previously observed. Further analysis revealed that ethyl 2-hydroxy-4-methylpentanoate, eluted in fraction which had an "additive" effect on the black-berry and fresh fruity aroma, does not play a direct role as a key compound in red wine aroma. In contrast, our findings highlighted its indirect contribution to wine aroma, showing that this ester contributed to a synergistic effect, enhancing the perception of fruity character. Finally, it was clearly demonstrated that this compound acts as a natural enhancer for black-berry and fresh fruit notes in red wine. It was also established that diacetyl, acetoin, acetic acid and γ-butyrolactone together played the same hypo-additive role as fractions of which they were eluted, presenting a "masking" effect on fresh fruity aroma. The impact of the last three compounds was demonstrated conclusively, even at subthreshold concentrations. These findings highlighted the existence of new remarkable perceptual interactions impacting overall and fresh-fruit aroma perception. The particular behavior, in a fruity mixture, of ethyl-propanoate, ethyl-3-hydroxybutanoate, butyl acetate and 2-methylpropyl acetate, present at subthreshold concentrations, was demonstrated. The presence of ethyl-3-hydroxybutanoate and 2-methylpropyl acetate in mixture led to a significant decrease of the olfactory threshold of fruity pool confirming their synergistic effect in the overall increase intensity. These compounds with close chemical structures, participate, both quantitatively and qualitatively, in the modulation of red wines’ fruity aromas acting as natural enhancers of black-berry and fresh-fruit aromas

L’expression aromatique fruitée des vins rouges a été le sujet de nombreuses études qui démontrent qu’au moins une composante de cette expression est le reflet d’interactions perceptives impliquant des esters. La plupart des travaux concernant les interactions perceptives jusqu’à ce jour se sont avérés descriptifs, très peu ayant cherché à déterminer leurs origines. Dans ce but, un outil analytique a été développé afin d’apprécier les changements de volatilité d’esters représentatifs de l’arôme fruité des vins rouges. Ainsi, les coefficients de partage de 9 esters ont pu être déterminés aussi bien dans une solution hydroalcoolique que dans un vin rouge désaromatisé. L’application de cet outil analytique aux interactions perceptives préalablement mises en évidence a permis d'observer des changements de volatilité des esters lors de leur mise en mélange avec d'autres composés volatils en solution. Ces changements de volatilité, synonymes de potentiels effets pré-sensoriels, vont dans le même sens que ceux observés lors de l’analyse sensorielle. L’utilisation d’un verre de dégustation possédant deux compartiments a permis de mettre en lumière le fait que certaines modifications sensorielles pouvaient être expliquées, pour partie au moins, par des effets pré-sensoriels. L'impact olfactif de 5 alcools supérieurs ainsi que de 15 composés issus du bois de chêne a pu être démontré grâce à de nombreuses reconstitutions aromatiques, et leur rôle de masquage de l’arôme fruité des vins rouges a pu être souligné. Le calcul des coefficients de partage des esters a permis de montrer que des changements de volatilité ont lieu au sein de la solution. Ces modifications peuvent être corrélées aux résultats obtenus lors de l’analyse sensorielle. Ainsi, il est possible d’expliquer, en partie, les effets de masquage de l’arôme fruité observés grâce aux seuils de détection et aux profils sensoriels, du fait de la diminution de la présence d’esters dans l’espace de tête venant stimuler le dégustateur. Globalement, nos travaux ont permis de mettre en évidence que la mise en mélange en solution de composés volatils pouvait se traduire par la modification de la volatilité des constituants du mélange et que certaines de ces interactions pré-sensorielles pouvaient conditionner l'expression aromatique fruitée due aux esters
A lot of studies highlighted the perceptual role of esters in fruity aromatic expression of red wines, demonstrating that at least partially it was due to perceptive interactions. Indeed, a lot of synergistic and masking effects have been brought to light in the past. However, the origin of these interactions remains unknown, although some authors suggested several levels where they can take place. In this goal, an analytical tool was developed to study the possible occurrence of esters volatility modifications. The application of this tool allowed determining partition coefficients of 9 esters in dilute alcohol solution and in dearomatized red wine. Thanks to perceptive interactions previously demonstrated by various authors, the application of this analytical tool highlighted modifications of esters volatility when compounds were mixed together in the solution. These modifications support the observations made with sensory analysis, indicating the existence of pre-sensorial effects. The use of a new tool consisting in a tasting glass with 2 compartments, reveals that these volatility changes may led to true sensorial modifications. Masking effect of fruity aroma due to 5 higher alcohols but also 15 wood by-products was highlighted using various aromatic reconstitutions. Esters partition coefficients calculation showed volatility modifications from the matrix to the gas phase. These data may be correlated with sensorial analysis results. Thus, it is possible to explain, at least partially, fruity aroma masking effect highlighted through detection threshold and sensory profile thanks to decrease in esters presence in headspace, and so a decline of taster’s olfactory stimulation. To conclude, our work showed that the mixture of volatile compounds in solution may result in modification of molecules volatility, and furthermore highlighted that these pre-sensorial interactions may impact fruity aromatic expression related to esters

La famille aromatique du végétal dans les vins rouges recouvre une large diversité de nuances. Nos travaux révèlent que celles-ci n’ont pas toujours de lien direct avec les composés connus (2-méthoxy-3-alkylpyrazines, alcools en C6). Aussi, après avoir été définis sensoriellement, les déterminants moléculaires de cette famille d’odeurs ont été recherchés en s’appuyant, à partir de vins représentatifs, sur différentes techniques de fractionnement (CLHP, distillation sous vide) puis MDCPG-O-SM. Une première origine de ces nuances a été développée, celle associée à la maturité des raisins. La présence du 1,8-cinéole (eucalyptol), avec des notes « vertes », selon une origine variétale en lien avec la maturité des raisins a pu être attestée dans les vins de Cabernet Sauvignon. La capacité d’un cépage à en produire des quantités significatives (Fer Servadou) ainsi qu’une origine exogène associée à la présence d’une espèce d’armoise au vignoble (Artemisia verlotiorum) sont aussi établis. Une autre origine d’apparition des nuances végétales a été considérée : le pressurage des marcs. Cette étude montre le lien étroit entre la catégorie aromatique des vins de presse et la famille du végétal. En outre, elle révèle la présence de divers marqueurs odoriférants, en particulier le (Z)-4-heptenol dont l’évolution est corrélée au niveau de pression et la contribution sensorielle établie, à l’inverse de la plupart des alcools en C6 ; de même qu’elle suggère l’implication de plusieurs composés carbonylés à l’odeur caractéristique des vins de presse. L’influence des paramètres technologiques (inertage, pression, SO2, FML) est aussi précisée. La présence du salicylate de méthyle comme marqueur de défense de la plante contre plusieurs maladies cryptogamiques (mildiou, black rot, esca) et comme contributeur à l’odeur végétale de certains vins rouges a enfin pu être démontrée
The green aromas family includes in red wines a large diversity of nuances. First, this study revealed that these nuances are not directly related to known compounds (e.g. 2-méthoxy-3-alkylpyrazines, C6 alcohols). After a sensory definition, the molecular determinants of these aroma nuances were investigated based on fractionation strategies including HPLC and vacuum distillation then MDGC-O-MS. A first source of nuances associated with grapes ripeness was developed. The presence of 1,8-cineole (eucalyptol) with a varietal origin was evidenced in Cabernet Sauvignon wines. The ability of a grape variety to produce significant amounts (Fer Servadou) and an exogenous origin associated with the presence of Artemisia species in vineyards (Artemisia verlotiorum) were also highlighted. Another origin, related to the pressing of grape marc was then considered. This study shown the connection between the aromatic category of press wines and the green aromas. Furthermore, it revealed the presence of odoriferous molecules including (Z)-4-heptenol, with a sensory contribution, associated to the increase of pressure in the press tank, but not for the majority of C6 alcohols. It also suggested the involvement of several carbonyl compounds in the characteristic odor of press wines. The influence of technological parameters (without oxygen, pressure, SO2, malolactic fermentation) was also specified. Finally, this study revealed the presence of methyl salicylate as a plant defense marker against several fungal diseases (downy mildew, black rot, esca) and as a contributor to fresh green aromas of certain red wines

碩士
輔仁大學
食品科學系
95
Aroma wheel is a unique tool to analyze key odorants and characterize corresponding notes in food. Currently, no aroma wheels of wine in Taiwan have been developed, therefore, misunderstanding the lexicons may occur due to the translation. This study aimed to develop a red wine aroma wheel in Chinese, and then applied to characterize local Black Queen red wines. Volatile compounds in red wine samples were collected using purge-and-trap method, and odorants were then extracted from the Tenax traps by solvent. Collected odor components were identified and quantified by GC–FID and GC–MS. Furthermore, GC–Olfactometry (GC–O) and Aroma Extraction Dilution Analysis (AEDA) were accomplished to confirm key aroma and quantify their odor activities to build up a wine aroma wheel. Results showed that the optimal collection was derived from using N2 purge at 180 ml/min in 30oC water for 9 hr, and then eluted by ether/pentane (1:1). The extract was analyzed by GC–FID installed with a CP–Wax column. Those process recoveries averaged 87.94% using 1-decanol as the internal standard. The wine samples and the corresponding extracts were characterized using AEDA and descriptive sensory evaluation, in which, 8 descriptor categories including fruity, dehydrated berry, herbaceous/vegetative, wood/floral, caramel, acid, oily were determined. In the GC–O and ADEA analyzes, 135 and 141 compounds were obtained from wine and its extract, respectively. Those compounds were then identified by GC–MS including 11 alcohols, 11 acids, 4 aldehydes, 5 ketones, 11 esters, 7 terpenes, 2 alkyl benzene, and 10 phenolic compounds. The descriptors found from the GC–O and AEDA process, in association with the Dilution Factor (FD) values, were subsequently integrated to develop the wine aroma wheel. The present study involving the GC–O and AEDA techniques is not only beneficial to develop food aroma wheels, but train descriptive ability of panelist.

Processing techniques for red wines and their potential health benefits have intensively been investigated, however, information relevant to the grape and wine industry in Texas is less frequently available. The overall objective of this work was to investigate the reduction of 3-alkyl-2-methoxypyrazines that can affect the quality of Texas wines and to study the health benefits of Texas wines. The methods used include SPME-GC-MS and molecular bioassays. The first objective was to demonstrate the anti-inflammatory potential effect of red wine polyphenols from Black Spanish wine (Vitis aestivalis hybrid) in colonic human fibroblast cells. Results show that an extract prepared from Black Spanish wine decreased gene expression and activation of NF-kB transcription factor and target proinflammatory cytokines and cell adhesion molecules. Induction of microRNA-126 (miR- 126) by wine extract was found to be one of the underlying molecular mechanism by which wine extract decreased vascular cell adhesion molecule (VCAM-1) and inflammation in colon cells. These mechanisms may be relevant to the prevention of iv inflammatory bowel disease (IBD) that may increase the risk for colon cancer. The second objective was to investigate the role of the green june beetle (GJB ) as exogenous source of MPs other than the multicolored Asian Lady beetle (Harmonia axyridis). Over the last decade, the green june beetle has been suspected to be a source of MPs based on intermittent reports from Texas growers of an atypical aroma and flavor reminiscent of crushed green June beetles (GJB). Specifically the North region of Texas seems affected. Results demonstrated GJB as source of 3-isopropyl-2- methoxypyrazine, where one GJB could elevate MPs above sensory perceptible levels in 4.3 gallons of wine. The incorporation of GJB to the winemaking process may contribute negatively to the sensory properties of Texas wines and therefore should be strictly controlled. The third objective was to explore the potential effect of micro-oxygenation treatment and accelerated aging techniques relevant for the state of Texas in the reduction of 3-Isobutyl-2-methoxypyrazine (IBMP), and 3-isopropyl-2-methoxypyrazine (IPMP) levels as determined by SPME-GC-MS. Results show that MPs were not affected by MOX or oak interaction. Although the data suggest that MOX and oak exposure do not directly affect MPs concentration. The fourth research objective was to explore the potential effect of three commercial available yeast strains, BM45, K1, and D80, on MPs levels in Black Spanish wines. Black Spanish wines were fermented with MB45 strain resulted in the highest amount of MPs. Conversely K1 and D80 yeast strains reduced IBMP levels in comparison with the control. An increase in IBMP was not expected. However it has been demonstrated that amino acids valine and leucine are MPs precursors. If Vitis v aestivalis hybrid grapes contained a similar methyltransferase enzyme found in Vitis vinifera grapes and S. cerevisiae contained similar IPMP biosynthesis pathway found in Pseudomonas perolens BM45 may have led to the increased IBMP observed in the fermentation. In addition we evaluated MPs levels of wines fermented over 20 days with a chemical defined grape juice medium containing a concentration of yeast available nitrogen of 200 mg N/L. Data suggest that wines fermented with BM45 and D80 yeast strains reduced IBMP but K1 yeast did not show any effect in comparison with the control. In addition MPs were evaluated in the yeast mannoproteins fraction. Results show the presence of IBMP in low concentration below the method detection limit. This data demonstrate for the first time that yeast mannoproteins binds IBMP. to evidence for interactions between mannoproteins secreted by the D80 yeast strain and IBMP. This work will provide valuable information regarding the potential health benefits of Vitis aestivalis hybrid grapes and reduction of MPs and thus improving the quality of Texas wines

The connection between a wine and its geographical origin is of great relevance in the context of wine production and marketing. Notions such as wine typicality and identity (at the foundation of Protected Designation of Origin), cru and terroir, all of great importance in the wine market, are based on the ability of a wine to express a ‘sense of place’. The relationship between a wine and its geographical origin is in large part associated with distinctive sensory characteristics, aroma in particular, characterizing wines from specific areas. From a chemical point of view, this implies the existence of unique and specific chemical profiles underlying recognizable sensory features of wine identity and typicality. In spite of the many studies aimed at characterizing the wines of different wine regions, the chemical bases of such aroma typicality are still poorly understood. The main aim of this study was therefore to investigate the existence of unique aroma signatures of Valpolicella Corvina and Corvinone wines from specific geographical origin. For this, grape from five different vineyards were harvested and vinified during three consecutive vintages, and the wines obtained were submitted to chemical and sensory analyses aimed at identifying quantifiable chemical markers and sensory parameters. Although large quantitative differences exist across different vintages, results highlighted the existence of clear chemical patterns distinguishing the wines from each vineyard. We define these aroma chemical signatures of geographical origins. The main drivers associated with these chemical signatures were terpenes and norisoprenoids, but also compounds mostly associated with fermentation, such as branched chain ethyl esters and acetate esters. The fact that the drivers of distinction were deriving both from grape and fermentation imply that the link between a wine’s composition and its geographical origin is the result of complex interactions between grape composition and yeast response to grape related factors. Among these, grape concentration of aroma precursors and YAN play a central role. The work also allowed to highlight patterns of odor similarities across the wines, providing evidence also for a sensory dimension of wine geographical identity. Evaluation of the impact of different S. cerevisiae strains on aroma signatures of geographical origin indicated that area of origin has a greater impact than yeast. In fact, from a chemical point of view, most volatile compounds that are thought to influence wine aroma were primarily affected by grape composition. Sensory analysis confirmed that grape composition induces greater differences than yeast strain too. Lastly, since a period of ageing is mandatory for most Valpolicella wines according to the product specification, the influence of aging on the aroma chemical signatures of the different wines was studied. Despite strong transformations of volatile chemical profile, aged wines retained an aroma chemical signature that was characteristic of their geographical origin. The results of this part of the work also allowed to clarify the role of different possible precursors in the formation of the potent balsamic/minty odorants 1,4- and 1,8-cineole during wine aging.

Tese de Doutoramento em Ciências Alimentar
A grande variabilidade e diversidade dos vinhos tintos produzidos em Portugal provenientes de castas nacionais Vitis vinifera L. justificam a sua caracterização aromática e físico-química. Essa caracterização, tem por objectivos, preservar a qualidade e a tipicidade dos vinhos de diferentes regiões, bem como, contribuir para aprofundar o conhecimento de castas que proliferam no mundo vitivinícola. Além disso, a caracterização do aroma de vinhos clonais apresenta um interesse inegável para a indústria vitivinícola, devido à importância que assume nos diversos aspectos qualitativo, produtivo e financeiro. De entre algumas centenas de compostos voláteis pertencentes a diversas famílias químicas e existentes em diferentes gamas de concentração, apenas uma parte contribui efectivamente para o aroma, aumentando a sua intensidade e complexidade no vinho. O conhecimento sobre a identidade e a concentração de tais compostos é fundamental para uma melhor compreensão do seu papel no aroma do vinho. Esta abordagem deverá ser complementada com a análise sensorial descritiva, para que se possa obter uma visão mais abrangente do aroma dos vinhos e da apreciação da sua qualidade. O programa Português de Selecção Clonal, criado em 1978, cujos objectivos são os de conhecer e seleccionar as melhores castas, visando aumentar a qualidade dos vinhos produzidos em Portugal, possui actualmente diversos clones certificados que são cultivados por viticultores. As castas Aragonez e Trincadeira estão entre as oito variedades tintas mais plantadas em Portugal, encontrando-se já certificados 7 e 6 clones, respectivamente. O conhecimento sobre as relações entre o papel individual de cada composto odorante e o papel global dos compostos responsáveis pelo aroma, são metas específicas a alcançar, de modo a ser possível realizar a escolha dos melhores clones para produzir vinhos de elevada qualidade. Este estudo teve como objectivo, contribuir para a caracterização dos componentes do aroma de vinhos tintos clonais e dos respectivos mostos e uvas, das castas Aragonez e Trincadeira Vitis vinifera L O desenvolvimento e a aplicação de um método de cromatografia em fase gasosa – olfactometria (GC-O), designado método de intensidade posterior, permitiu, pela primeira vez, estabelecer os perfis odorantes de cada casta e, simultaneamente, diferenciar os vinhos clonais de ambas as castas e os mostos dos clones de Aragonez. Assim, em todos os vinhos clonais foram detectados diversos compostos odorantes, tendo apresentado intensidades médias mais elevadas: o ácido 3-metilbutanóico, o 2-feniletanol, o Furaneol™ e o 4-vinilguaiacol. A quantificação de alguns compostos odorantes utilizando a cromatografia em fase gasosa acoplada ao detector de ionização de chama (GC-FID) encontrados nos vinhos clonais e respectivos mostos e uvas, demonstrou a existência de diversas diferenças estatísticas entre os clones. Os compostos Furaneol™ e homofuraneol, caracterizados com os descritores de odor a açúcar queimado (tipo caramelo) e algodão doce, foram identificados nos vinhos clonais de Aragonez e Trincadeira bem como nas fracções livres e ligadas dos mostos de Aragonez, indicando a sua origem varietal. Demonstrou-se por GC-O, GC-FID e análise sensorial descritiva que o ano de vindima apresentou uma influência relevante nos vinhos clonais da casta Trincadeira. A análise discriminante linear aplicada aos dados obtidos, revelou a existência de algumas variáveis discriminantes que poderão ser utilizadas para se obter uma correcta classificação dos vinhos clonais provenientes das duas vindimas em estudo. Os atributos de aroma, adocicado, herbáceo, animal, frutos secos, frutos vermelhos, especiarias e madeira, utilizados pelo painel sensorial, foram úteis para a obtenção do perfil de aroma dos vinhos clonais de Aragonez e de Trincadeira. A não quantificação de compostos monoterpénicos e a escassez de norisoprenóides em C13 nas uvas e nos mostos são indicadores de que as castas Aragonez e Trincadeira podem ser classificadas como castas neutras. A informação obtida por GC-O e pela análise sensorial descritiva sugere uma elevada utilidade destas “ferramentas sensoriais” para o controlo da qualidade dos vinhos.
The large variability and diversity of red wines produced in Portugal with Portuguese Vitis vinifera L. cultivars fully justify their chemical and aroma characterisation. The objectives of this characterisation are to preserve the quality and tipicity of the wines from different regions and to contribute to the deeper knowledge of grape varieties in the world. Furthermore, the characterisation of the aroma of clonal wines is of undeniable interest to the winemaking industry, due to its productive, financial and qualitative aspects. Among hundreds of volatile compounds of distinct classes and a wide range of concentrations present in red wines, only a part contribute effectively to the aroma, enhancing the intensity and complexity of the wine flavour. Knowing the identity and the concentration of such compounds in wines is crucial for a better understanding of their role in defining wine aroma. This approach should be complemented with descriptive sensory analysis in order to give an overview of the aroma of wines and appreciation of the general quality of wines. The Portuguese Clonal Selection Program was created in 1978 with the objectives of getting to know and select our best varieties of grapes and to increase the quality of wines produced in Portugal. Nowadays it has several certified clones commonly used by grape-growers. Aragonez and Trincadeira are among the eight more planted red grape varieties in Portugal and respectively seven and six clones of both cultivars have already been certified. The knowledge of the relationships between the individual role of each odourant compound and the global role of the overall aroma compounds are specific targets that we need to know in order to be able to choose the best clones to produce the best wines. The aim of this study was to contribute for the characterisation of the aroma of distinct clonal red wines, musts and grapes, from Vitis vinifera L. cultivars Aragonez and Trincadeira. The development and application of a gas chromatography-olfactometry (GC-O) posterior intensity method allowed, for the first time, the establishment of the odourant profiles of each cultivar and, simultaneously, the differentiation of the clonal wines among Aragonez and Trincadeira varieties and clonal musts from Aragonez. Several odourant compounds were detected, having the highest average intensities in all clonal wines: 3-methylbutanoic acid, 2-phenylethanol, Furaneol™, and 4-vinylguaiacol. The quantification by gas chromatography-flame ionization detector (GC-FID) of some of the odourant compounds found in the clonal wines as well as those found in musts and grapes showed several statistical differences among clones Furaneol™ and homofuraneol, described with a burnt sugar (caramel-like) and candy-cotton odour descriptors, were identified in Aragonez and Trincadeira clonal wines as well as in both free and bound fractions of Aragonez musts, indicating their grape-derived origin. Vintage had a significant influence on Trincadeira clonal wines, as was demonstrated by GC-O, GC-FID and by descriptive sensory analysis. Stepwise linear discriminant analysis applied to data obtained from the previous analyses revealed some discriminating variables that can be used to obtain a correct classification of the clonal wines from the two distinct vintages. The aroma attributes sweet, herbaceous, animal, dried fruits, red fruits, spicy and woody, used by the sensory panel, were useful in obtaining the aroma profile of the Aragonez and Trincadeira clonal wines. The inexistence of quantified monoterpenic compounds and the poorness in C13-norisoprenoids found in musts and grapes indicated that Aragonez and Trincadeira can be classified as neutral cultivars. The information obtained by GC-O and descriptive sensory analysis suggested the usefulness of these “sensory tools” for controlling wine quality.

"In the process of red wine aging, the barrel plays a fundamental role both in the contribution of aromas and in the stabilization of the wine and its color. There are, however, different types of barrels, depending on materials, species and origin of the oak, morphology and geometry, and capacity (from 225 liters to larger formats of 300 and 500 liters). The purpose of this work is to perform the Life Cycle Assessment (LCA) of these barrel formats and compare them with the 225-liter Bordeaux barrel, providing detailed information on these products that can serve as a reference for their use in the calculation of the impact of its application in the wine aging processes. We will consider, for the realization of the present LCA, all the phases of process and manufacture of the barrel that cover from the contribution of materials and their processing until the final storage."