Letteratura scientifica selezionata sul tema "Sauvignon blanc"

Methoxypyrazines are the principal aroma components responsible for the vegetative and herbaceous green bell-pepper flavour of Sauvignon blanc wines produced in Moravia. The aroma profiles of 8 samples of Moravian Sauvignon wines were analysed; the levels of 3-isobutyl-2-methoxypyrazine varied in the range of 4.7–17.0 ng/l. The commercial Sauvignon aroma preparation Aroma Fantasia S, available in the region, was analysed; the product contained the 3-isobutyl-2-methoxypyrazine, and in negligible concentrations also anethol and ethylbenzoate. The Moravian Sauvignon blanc wine samples spiked with different amounts of aroma preparation were evaluated by hedonic sensory analysis, to estimate the meaningfulness of such illegal improvement. The most preferred concentration ranged from 5 ng/l to 10 ng/l, which are the natural levels of MP in Moravian Sauvignon blanc wines, therefore the addition of aroma at this level, which can be detectable with difficulties, has no reason. The less sophisticated adulteration of wine, such as the production of artificial Sauvignon blanc wine by the addition of MP into less distinctive wines, is easily detectable according to the aroma profile.

Breeding technologies exploiting marker-assisted selection have accelerated the selection of new cross-bred pathogen-resistant grapevine varieties. Several genotypes have been patented and admitted to cultivation; however, while their tolerance to fungal diseases has been the object of several in vitro and field studies, their productive and fruit composition traits during ripening are still poorly explored, especially in warm sites. In this study, five white pathogen-resistant varieties (PRV) listed as UD 80–100, Soreli, UD 30–080, Sauvignon Rytos, Sauvignon Kretos were tested over two consecutive seasons in a site with a seasonal heat accumulation of about 2000 growing degree days (GDDs), and their performances were compared to two Vitis vinifera L. traditional varieties, Ortrugo and Sauvignon Blanc. Berries were weekly sampled from pre-veraison until harvest to determine total soluble solids (TSS) and titratable acidity (TA) dynamics. All tested PRV exhibited an earlier onset of veraison and a faster sugar accumulation, as compared to Ortrugo and Sauvignon Blanc, especially in 2019. At harvest, Sauvignon Blanc was the cultivar showing the highest titratable acidity (8.8 g/L). Ortrugo and PRV showed very low TA (about 4.7 g/L), with the exception of Sauvignon Rytos (6.5 g/L). However, data disclose that Sauvignon Rytos higher acidity at harvest relies on higher tartrate (+1.1 to +2.2 g/L, as compared to other PRV), whereas in Sauvignon Blanc, high TA at harvest is due to either tartaric (+1 g/L, compared to PRV) and malic (+2.5 g/L, compared to PRV) acid retention. Overall, Sauvignon Rytos is the most suited PRV to be grown in a warm climate, where retaining adequate acidity at harvest is crucial to produce high-quality white wines. Nevertheless, canopy and ripening management strategies must be significantly adjusted, as compared to the standard practice employed for the parental Sauvignon Blanc.

The world’s changing climate is placing great pressure on the resources for sustainable viticulture. With this, it has become necessary to investigate grape varieties that are well adapted to hot climates. This study investigated whether two Cypriot varieties (Xynisteri and Maratheftiko) responded differently to Shiraz and Sauvignon Blanc grown under different irrigation regimes (full, 50% and 25%). Irrigation trials were established in Cyprus in 2019 and in Australia in 2020/2021. Vine growth and physiology and fruit composition (field trial only) measurements were recorded. The trial in Cyprus in 2019 demonstrated that for all three irrigation regimes, Xynisteri had higher stem water potential, stomatal conductance, chlorophyll and greater biomass than Sauvignon Blanc under all irrigation regimes. In 2020/2021, Xynisteri had a greater biomass than Maratheftiko and Sauvignon Blanc, with Shiraz having the lowest. Under reduced irrigation, Xynisteri and Maratheftiko had higher stem water potential, stomatal conductance and chlorophyll content than Shiraz and Sauvignon Blanc. These results indicate that Xynisteri in particular may possess better cultivar-specific growth traits than Shiraz and Sauvignon Blanc when grown under the same environmental conditions and in turn may be a more appropriate choice in areas where water is limited.

Pruning experimental studies have been performed in different vineyards, in France, USA and Australia. This article investigates and models the effects of pruning quality on the installation of desiccation cones and wood necrotization. Two different modalities of pruning, short and high pruning, were performed at the same period each year on three cultivars in Bordeaux (Cabernet Sauvignon and Sauvignon Blanc) and Charente (Ugni Blanc) wine regions. In the short typ of pruning, the diaphragm was damaged but, in the high one, a 2–3 cm woody length was left immediately above the diaphragm. None of the three cultivars showed any correlation between necrosis length and spur diameter (R2 < 0.1925). Analysis of the Ugni Blanc, 8 months after pruning, showed significantly more necrosis length (>60%) than either Cabernet Sauvignon (31–41%) or Sauvignon Blanc (25–55%). Desiccation cone necrotization rates also varied with the vintage, particularly for Ugni Blanc. 4 or 8 months after pruning, the newly-installed desiccation cones could then be analysed. High pruning stopped the desiccation cones at the diaphragm, which ensured that the sap flow path remained unaffected.

<p style="text-align: justify;"><strong>Aims</strong>: A terroir can be defined as a grouping of homogenous environmental units, or natural terroir units, based on the typicality of the products obtained. Terroir studies therefore require an investigation into the response of grapevines to the natural environment.</p><p style="text-align: justify;"><strong>Methods and results</strong>: A network of plots of Sauvignon blanc and Cabernet Sauvignon were delimited in commercial vineyards in proximity to weather stations and their response monitored for a period of seven years. Regression tree methodology was used to determine the relative importance of the environmental and management related variables and to determine regression trees for each dependent variable. Excepting for scion clone, which had a high relative importance for bunch mass of Sauvignon blanc and yield to pruning mass index of Cabernet Sauvignon, no other nonenvironmental variable included in the analyses appeared to have a strong effect on grapevine performance and wine character. The performance of Cabernet-Sauvignon was related to the potassium content of the subsoil and climate (temperature and rainfall) of the season. The performance of Sauvignon blanc appeared to be related to soil texture, wind exposure and temperature of the site and season, both during the green berry growth stage and the month prior to ripening.</p><p style="text-align: justify;"><strong>Conclusions</strong>: From the results presented, it appears that environmental parameters have an overriding effect on the performance of both Cabernet Sauvignon and Sauvignon blanc but that these two cultivars react differently to environmental stimuli.</p><p style="text-align: justify;"><strong>Significance and impact of study</strong>: These results should contribute to the identification of viticultural terroirs with specific agronomic potential for Cabernet-Sauvignon and Sauvignon blanc.</p>

O objetivo deste trabalho foi avaliar o comportamento vegetativo e produtivo das variedades de videira Cabernet Sauvignon, Merlot e Sauvignon Blanc, e a composição da uva em São Joaquim, Santa Catarina. Foram avaliadas plantas de um vinhedo comercial, cultivado em espaldeira, a 1.293 m de altitude, durante os ciclos fenológicos 2005/2006 e 2006/2007. As variáveis meteorológicas, a fenologia, o desenvolvimento do dossel e a composição da uva na colheita foram comparados entre os ciclos. As temperaturas mais amenas influenciaram o ciclo fenológico das variedades Cabernet Sauvignon, Merlot e Sauvignon Blanc, que é mais longo e tardio que nas outras regiões vitícolas do Brasil. Houve influência significativa da precipitação pluvial sobre a maturação da uva, no ciclo 2006/2007. Os índices de desenvolvimento indicam a necessidade de ajuste no manejo do dossel para um maior equilíbrio entre o crescimento vegetativo e a produção. As variedades Cabernet Sauvignon, Merlot e Sauvignon Blanc apresentam elevada qualidade da uva no momento da colheita, sendo adequadas ao cultivo em São Joaquim, SC.

Key varietal characteristics of Sauvignon Blanc, including the descriptors of ‘green’ and ‘tropical fruit’, are mostly attributed to methoxypyrazines and volatile thiols, while monoterpenes, higher alcohols, esters, fatty acids, and other volatile compounds also add complexity and fruity notes to the wines. During the winemaking and ageing period, oxidation decreases the concentrations of these compounds and diminishes the flavours derived from this aromatic grape variety. Therefore, antioxidants, such as sulfur dioxide, are commonly utilized in Sauvignon Blanc wine production for better preservation of those beneficial primary aromas. This review focuses on key varietal aromas in Sauvignon Blanc wine and how they are influenced by oxidation, and SO2 alternatives, including ascorbic acid, glutathione, and glutathione-enriched inactivated dry yeasts, that can be used in winemaking as antioxidants.

A trial was conducted during the 2005–2006 season in order to determine the effects of different leaf-to-fruit ratios on yield components and fruit composition in four Vitis vinifera L. cultivars. The treatments consisted of selecting shoots of four lengths (>1.3 m, 1.3–0.8 m, 0.8–0.4 m, and <0.4 m) with two crop levels (1–2 clusters/shoot), which allowed defining eight ratios. Berry composition and yield components were measured. The treatments affected the accumulation of soluble solids in “Sauvignon blanc”, “Cabernet Sauvignon”, and “Syrah”, delaying it as the ratio decreased. All yield components were affected in “Sauvignon blanc”, while bunch weight and the number of berries per bunch were altered without a clear trend. None of the yield components were affected in “Cabernet Sauvignon”, while the lowest ratio presented the lowest number of berries per bunch in “Syrah”. Total polyphenol index (TPI) was affected in “Carmenère” without a clear trend. A highly significant correlation was found between shoot length and leaf area in all studied cultivars. As the ratio increased, the shoot lignification increased in “Sauvignon blanc”. However, studies must be conducted during more seasons to establish better conclusions about the effects of leaf-to-fruit ratios on yield and fruit composition.

O objetivo deste trabalho avaliar o efeito do aumento do número de gemas na intensidade de antracnose na videira ‘Sauvignon Blanc’ cultivada em região de elevada altitude de Santa Catarina. Os tratamentos consistiram em quatro diferentes cargas de gemas deixas na poda invernal: 15 gemas/planta, 30 gemas/planta, 50 gemas/planta e 75 gemas/planta. Os dados foram submetidas à análise de variância (ANOVA) e quando detectadas efeitos de tratamento, procedeu-se o teste de comparação de médias pelo teste Tukey a 5% de probabilidade de erro. O número de gemas por planta influenciou a incidência e severidade de antracnose nas folhas e ramos da videira Sauvignon Blanc, observando-se que plantas podadas com 75 gemas por planta apresenta maior intensidade de antracnose, enquanto, plantas podadas com 15 gemas, observou-se menor intensidade de antracnose nas folhas e ramos da videira Sauvignon Blanc.

<p>Phenolic compounds are key components of wine, since they contribute to wine characteristics such as colour, astringency and bitterness. They also act like antioxidants, with mechanisms involving free-radical scavenging that could prevent cardiovascular diseases and cancer. The aim of the present work was to compare the obtained results of total polyphenols content and antioxidant potential (AOP) of several white wines (welschriesling and sauvignon blanc) during ageing on fine lees. The total polyphenols content decreased in average for 16.1 % in welschriesling wines and for 18.7 % in sauvignon blanc wines in the period of three months of wine ageing on lees. In the same period AOP of wines decreased in average for 16.0 % in welschriesling wines and for 8.0 % in sauvignon blanc wines. Expectedly, the samples with added oak chips in grape must had higher antioxidant potential than others.</p>

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.

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Agrárias, Programa de Pós-Graduação em Recursos Genéticos Vegetais, Florianópolis, 2014.
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O Estado de Santa Catarina tem se destacado no cenário nacional pelo potencial na produção de vinhos finos de qualidade, em função da altitude. No entanto, algumas regiões de Santa Catarina, como o município em estudo, Rancho Queimado, apresentam elevada pluviosidade no período de maturação e colheita, além de riscos de ocorrência de geadas e granizos, o que compromete a qualidade da uva. A cobertura plástica dos vinhedos surge como uma opção para o controle destas adversidades climáticas, principalmente, para evitar a ação do excesso de precipitação durante a maturação das uvas. No entanto, a utilização e o conhecimento desta técnica é incipiente em uvas destinadas à vinificação. Portanto, é importante a caracterização climática e a definição dos parâmetros ecofisiológicos de vinhedos sob cobertura para que seja explorado ao máximo o potencial vitícola e enológico destes locais. O objetivo desse trabalho foi avaliar as influências microclimáticas estabelecidas pela cobertura plástica sobre a fisiologia, o potencial produtivo e a qualidade vitienológica da videira (Vitis vinifera L.). As variedades avaliadas foram Sauvignon Blanc, Cabernet Sauvignon e Merlot, no município de Rancho Queimado-SC (altitude de 1000 metros, latitude de 27°42' 26" S, longitude 49°04' 17? W), durante os ciclos 2011/2012 e 2012/2013. O vinhedo foi implantado no ano de 2009 em sistema de condução espaldeira, sobre porta-enxerto Paulsen 1103, com espaçamento de 3,0 m x 1,0 m. As variáveis climáticas avaliadas foram: temperatura do ar (ºC); precipitação pluviométrica (mm); umidade relativa do ar (%); radiação solar global (Wm-2) e radiação fotossintética ativa (µmol fótons m-2s-1). As análises ecofisiológicas compreenderam as avaliações fenológicas entre a brotação e a colheita, área foliar, teores foliares de clorofila, avaliação das trocas gasosas e rendimento. Na colheita foram avaliados o teor de sólidos solúveis totais, acidez total titulável, pH, índice de polifenóis totais e antocianinas manoméricas totais, trans-resveratrol, catequina e epicatequina. Com relação à temperatura, as máximas diárias são as que mais sofrem influência do uso da cobertura plástica, com aumento em média de 2?C. As médias das temperaturas máximas, mínimas e médias, assim como a amplitude térmica e o somatório térmico em graus-dia são superiores no vinhedo coberto quando comparados ao descoberto. Enquanto que a radiação global, a radiação fotossinteticamente ativa, a umidade relativa do ar e a precipitação pluviométrica foram maiores no vinhedo descoberto. A presença da cobertura plástica reduz em 28% a radiação fotossinteticamente ativa incidente sobre o dossel vegetativo, e em 32% a radiação solar global em todo o ciclo da videira. Devido ao aumento no somatório de graus-dia, a cobertura plástica sobre o vinhedo antecipou o início da brotação e demais eventos fenológicos até a mudança de cor das bagas. Entretanto, a redução da radiação solar proporcionou o prolongamento do processo de maturação das uvas. Uvas das variedades Cabernet Sauvignon e Merlot produzidas na área coberta apresentaram menores teores de acidez e maiores teores de sólidos solúveis totais, pH, polifenóis totais, catequinas e epicatequinas. Uvas cobertas de Merlot apresentram maiores teores de antocianinas manoméricas totais e de resveratrol. Houve incremento no teor de sólidos solúveis totais em uvas Sauvignon Blanc sob cobertura plástica. O teor de resveratrol foi reduzido em uvas das variedades Cabernet Sauvignon e Sauvignon Blanc cobertas, enquanto o conteúdo de catequinas e epicatequinas foram superiores em comparação as uvas do vinhedo descoberto. As uvas produzidas a partir do vinhedo coberto apresentam melhor qualidade do que em céu aberto, como consequência da melhor sanidade dos cachos. Os resultados obtidos na avaliação das trocas gasosas sugerem que o processo fotossintético foi beneficiado pelo microclima propiciado pela cobertura, e isto foi refletido na maior produtividade das plantas. Houve aumento das concentrações dos pigmentos nas folhas de plantas cobertas das variedades Cabernet Sauvignon na fase de maturidade e Sauvignon Blanc no ciclo 2012/13. As plantas cobertas das três variedades avaliadas mantiveram suas folhas cerca de 28 dias a mais do que as plantas descobertas. A presença da cobertura plástica aumenta a produtividade das variedades Cabernet Sauvignon em 54% e Sauvignon Blanc em 30%. E melhora a relação área foliar:produtividade de todas as variedades avaliadas.

Abstract : In last years viticulture in high altitude regions of Santa Catarina State has been highlighted for producing wines of unique quality in Brazil. Some regions of Santa Catarina State, as the city under study, Rancho Queimado, have high rainfall in maturation and harvest period, as well as risk of occurrence of frosts and hail, which compromises grape quality. The plastic cover is an option to control weather adversities especially to avoid excessive rainfall during the grape ripening. However, the use and knowledge of this technique is incipient to grapes for winemaking. The objective of this study was to evaluate the microclimate influences established by the plastic cover on the physiology, production potential and enological quality of the vine (Vitis vinifera L.). The varieties evaluated were Sauvignon Blanc, Cabernet Sauvignon and Merlot in the city of Rancho Queimado - Santa Catarina State (latitude 27 ° 42 '26 "S, longitude 49 ° 04' 17" W, altitude 1,000 meters), during seasons 2011/2012 and 2012/2013. The vineyard was planted in 2009, trained in vertical shooting positioning trellis, grafted on 1103P and spacing 3.0 x 1.0 m. Climatic data evaluated were precipitation (mm), relative humidity (%), maximum, air temperature (°C), global radiation (Wm-2) and photosynthetically active radiation (µmol photons m-2s-1). Ecophysiological analyzes were: phenological assessments between budbreak and maturity, leaf area, leaf chlorophyll content, leaf gas exchanges and yield. At harvest were evaluated total soluble solids, total acidity, pH, total polyphenols, total monomeric anthocyanins, trans-resveratrol, catechin and epicatechin. Regard to temperature, daily maximum suffers the greatest influence by the use of plastic cover, with an average increase of 2°C. The maximum, minimum and mean temperatures as well as thermal amplitude and heat summation (growing degree-days) are higher in the covered vineyard. While global radiation, photosynthetically active radiation, relative humidity and precipitation are higher in the uncovered vineyard. Due to the increase in the heat summation, the plastic cover antecipates budbreak and other phenological events until veraison. However, the reduction of solar radiation prolong the maturation process. Cabernet Sauvignon and Merlot produced under plastic cover present lower acidity and higher total soluble solids, pH, total polyphenols and catechins. Merlot produced under plastic cover presents higher contents of total monomeric anthocyanins and trans-resveratrol. Sauvignon Blanc under plastic cover presents higher contents of total soluble solids. The resveratrol content is reduced in covered Cabernet Sauvignon and Sauvignon Blanc, while the content of catechins and epicatechins are higher in the uncovered vineyard. The presence of the plastic cover reduces 28% of photosynthetically active radiation incident on the canopy, and 32% of global solar radiation throughout the cycle of the vine. The grapes produced in the covered vineyard have better quality as a result of better cluster sanity. The plastic cover influences vine phisiology. The results obtained in the evaluation of leaf gas exchange suggest that the photosynthetic process is benefited by the microclimate afforded by the cover, and this is reflected in higher plant yield. The plastic cover also increases the pigments concentrations in the leaves of Cabernet Sauvignon and Sauvignon Blanc (season 2012/13). The plants covered from the three varieties keep their leaves about 28 days longer than the uncovered ones. The plastic cover increases 54% of Cabernet Sauvignon yield and 30% of Sauvignon Blanc yield. And also improves the leaf area:yield ratio of all tested varieties.

The grape variety Sauvignon Blanc (SB) is the flagship of New Zealand’s wine industry and accounted for over 75 % of the value of total wine exports in 2008. Two volatile thiols, 3-mercaptohexan-1-ol (3MH) and 3-mercaptohexyl-acetate (3MHA), reminiscent of grapefruit and passion fruit respectively, are critical for the main varietal characters in New Zealand SB. These aromatic thiols are not present in the grape juice, but are synthesized and released by the yeast during alcoholic fermentation from non-aromatic precursors. The aim of this work was to elucidate the underlying genetics of volatile thiol synthesis in yeast (Saccharomyces cerevisiae) during alcoholic fermentation of grape juice. A gene-deletion strategy was chosen for the investigation of putative genes influencing 3MH and 3MHA release. The first part of this thesis optimized fermentation conditions in grape-juice-based media, which enabled auxotrophic laboratory strains, derived from S288C, to ferment grape juice to completion with high efficiency. Key steps to achieving this goal were the supplementation of the grape juice with higher than recommended amounts of amino acids, which increased the fermentation rate of auxotrophic yeast strains. Lysine auxotrophic strains especially benefited from this measure. In combination with the dilution of SB grape juice by 25 % with synthetic grape juice without sugars, the auxotrophic laboratory yeast BY4743 was able to metabolize all sugars in the grape juice-based media in a time frame similar to that of a commercial wine yeast. The key properties of the resulting wine were comparable to wine made with a commercial wine yeast under the same conditions. In the second part, these newly developed fermentation conditions were employed to screen 69 single-gene deletion strains in the laboratory yeast background BY4743. The list of the 69 candidate genes was compiled by combining existing knowledge about thiol production in yeast with the mining of several biological databases. Screening of the single-gene deletions revealed 17 genes which caused biologically relevant increases or decreases in volatile thiol production, but none abolished it. The majority of the 17 genes were related to the sulfur and nitrogen metabolism in yeast. A subset of these thiol-influencing genes were also deleted in a wine yeast, and were overexpressed in both wine yeast and laboratory yeast, to gain more insight in their regulatory effects. The findings confirmed that sulfur and nitrogen metabolism in yeast were important in regulating 3MH and 3MHA synthesis. Different sulfur and nitrogen sources were added to the grape must prior to fermentation and their effect on thiol release was studied. It was found that nitrogen sources urea and DAP, as well as, the sulfur compound S-ethyl-L-cysteine (SEC) increased 3MH and 3MHA concentrations in the resulting wines. The addition of cysteine to grape juice fermented with wine yeast deleted in genes CYS3 and CYS4 more than doubled total thiol production. Mapping approaches to investigate thiol production in yeast were employed in the final part of this thesis. Genetically mapped F2 progeny of a cross between a low thiol-producing yeast strain and a high-thiol producer were screened for their thiol phenotype. The 3MH and 3MHA phenotypes across 48 screened F2 progeny resembled normal distributions, indicating a quantitative trait. Subsequent mapping identified a locus on chromosome 14 with a small effect on the 3MHA phenotype, but no obvious candidate genes were evident in the region. Another approach to investigate the evolution of volatile thiols in yeast included the use of SEC, a thiol compound resembling the cysteinylated precursor of 3MH, as a sole nitrogen source in a yeast growth assay. It was found that most wine yeast, European yeast isolates and laboratory yeasts could utilize SEC as a nitrogen source, whereas various other S. cerevisiae isolates could not. Crosses between three pairs of Sec- and Sec+ yeast strains strongly indicated that this trait was monogenically inherited. However, no direct correlation between the SEC phenotype and volatile release could be observed. Genetic mapping experiments in one SEC-segregating yeast population linked this SEC phenotype to the leu2-D0 deletion in a cross between a Leu+ and Leu- yeast strain. It was shown that leucine auxotrophy most likely caused the Sec- phenotype. In a second F2 population of a cross between prototrophic Sec+ and Sec- strains, strong linkage was established to a region on chromosome 6 containing two candidate genes, DUG1 and IRC7. DUG1 was proved not to be the cause of the SEC phenotype, whereas IRC7 remains a strong candidate gene.

Thesis (MSc (Wine Biotechnology))--University of Stellenbosch, 2011.
Includes bibliography.
ENGLISH ABSTRACT: The varietal character of Sauvignon blanc wine is mostly defined by the balance between tropical and green vegetative flavour nuances. Grape derived methoxypyrazines are the main aroma contributors towards green vegetative flavours. Methoxypyrazines are heat and light sensitive. Due to warm climatic conditions in South Africa, methoxypyrazine levels decrease during grape ripening. The addition of food flavourings to Sauvignon blanc wine, a practice known as spiking, has occurred in the past to improve the green character of the wines. Adding flavourings to wine and selling the wine as natural certified wine is illegal in South Africa. Currently, adulterated Sauvignon blanc wines are identified using gas chromatography–mass spectrometry (GC-MS) and liquid chromatography–mass spectrometry (LC-MS) methods to quantify methoxypyrazines and compare levels to an established database. Although of high sensitivity, GC-MS and LCMS methods are costly and time consuming, therefore not optimal for routine screening of wines. Hence the need for the development of a fast and cost effective method for routine screening of large amounts of wines to identify adulteration. Small scale vinification practices were used to prepare experimental Sauvignon blanc wine. Flavourings were added to Sauvignon blanc grape juice before fermentation, during the preparation of experimental spiked wines. Control wines, containing no flavouring, were also prepared. Commercial wines were spiked after fermentation and bottling. Each wine was only spiked with a single flavouring. The flavourings added were the juice of homogenised fresh green peppers and commercially available flavourings for wine. The following commercial flavourings were used: green pepper, asparagus, grassy and tropical. The above mentioned wines were analyzed using Fourier transform infrared (FT-IR) spectroscopy, GC-MS, LC-MS and descriptive sensory analysis. The FT-IR techniques used were Fourier transform mid infrared (FT-MIR) transmission, FT-MIR attenuated reflection and Fourier transform near infrared (FT-NIR) reflection spectroscopy. The data was interpreted using the following multivariate statistical techniques: principal component analysis (PCA), partial least squares discrimination (PLS-D) and conformity testing. Multivariate models constructed from FT-MIR and FT-NIR data were able to discriminate between spiked and control wines. Sensory analysis results clearly showed differences between non-spiked wines and spiked wines with 3-isobutyl-2-methoxypyrazine concentrations 10 times higher than naturally occurring in wine. Differences between control and spiked wines with concentrations of 3-isobutyl-2-methoxypyrazine similar to concentrations naturally occurring in wines could not be detected to prove adulteration conducting sensory analysis. However, differences between control and spiked wines with levels of 3-isobutyl-2-methoxypyrazine similar to levels naturally occurring in wines could be detected using FT-IR data in conjunction with multivariate statistics. This study showed that, FT-IR spectroscopy in conjunction with multivariate statistical methods can be a possibility for the screening and identification of wines suspected of adulteration in terms of added flavourings. Descriptive sensory analysis also proved to be a potentially useful tool. However screening and training of potential panel members are time consuming.
AFRIKAANSE OPSOMMING: Die variëteitskarakter van Sauvignon blanc wyn word grotendeels gedefinieer deur die balans tussen tropiese en groen vegetatiewe aromas. Metoksipirasiene is die hoof aroma verbindings wat verantwoordelik is vir groen vegetatiewe aromas. Metoksipirasien is hitte- en ligsensitief. Warm klimaatsomstandighede in Suid-Afrika het tot gevolg dat metoksipirasien konsentrasies daal tydens druif rypwording. Sauvignon blanc wyne is in die verlede vervals deur middel van die byvoeging van vars groen soetrissies om die groen vegetatiewe karaktereienskappe van die wyne te bevorder. Die byvoeging van geurmiddels of plantekstrakte by wyn en verkoop van daardie wyn as gesertifiseerde natuurlike wyn is onwettig in Suid-Afrika. Tans word vervalsde wyne met behulp van gaschromatografie-massaspektrometrie (GC-MS) en vloeistofchromatografie-massaspektrometrie (LC-MS) opgespoor. Kwantifisering van metoksiepirasien konsentrasies in wyne en druiwesappe word vergelyk met konsentrasies in ‘n bestaande databasis. Alhoewel GC-MS en LC-MS hoë sensitiwiteitsmetodes is, is dit duur en tydrowende metodes, dus nie optimaal vir roetine sifting nie. Dus word ‘n koste- en tydseffektiewe roetine metode benodig om vervalsing van wyne op te spoor. Eksperimentele wyne is op klein skaal berei. Geurmiddels is voor fermentasie by die druiwesap gevoeg. Kontrole wyne waarby geen geurmiddels gevoeg is nie, is ook berei. Kommersiële wyne is gegeur na fermentasie en bottelering. Elke wyn is met ‘n enkele geurmiddel gegeur. Gehomogeniseerde vars groen soetrissie asook kommersieel beskikbare geursels vir wyn is gebruik. Die volgende kommersiële geursels is gebruik: groen soetrissie, aspersie, gras en tropiese geursel. Die volgende analitiese tegnieke is gebruik vir analisering van bogenoemde wyne: Fourier transformasie infrarooi (FT-IR) spektroskopie, GC-MS, LC-MS en beskrywende sensoriese analise. Die spesifieke FT-IR tegnieke wat gebruik is, is: Fourier transformasie mid-infrarooi (FT-MIR) transmissie, FT-MIR verswakte weerskaatsing en Fourier transformasie naby-infrarooi (FT-NIR) reflektansie. Die volgende multiveranderlike statistiese tegnieke is gebruik ter interpretasie van data: hoof komponent analise (PCA), parsiële kleinste kwadraat diskriminant analise (PLS-D) en gelykvormigheidstoetsing. Multiveranderlike modelle, bereken met behulp van FT-MIR en FT-NIR data, kon diskrimineer tussen gegeurde en kontrole wyne. Resultate wat verkry is tydens sensoriese analises het duidelike verskille uitgewys tussen gegeurde en kontrole wyne met betrekking tot 3-isobutiel-2- metoksipirasien konsetrasies waar 3-isobutiel-2-metoksipirasien konsentrasies 10 keer hoër was as wat natuurlik voorkom in wyn. Geen beduidende verskille kon waargeneem word in gevalle waar wyne vervals is met laer konsentrasies van geurmiddels deur sensoriese data te ontleed nie. Nietemin, statisitiese verskille tussen kontrole en vervalsde wyne kon waargeneem word vir lae-konsentrasie-geurmiddel vervalsde wyne deur FT-IR data met behulp van multiveranderlike statisitiese metodes te ontleed. Hierdie studie het gewys dat FT-IR in kombinasie met multiveranderlike statistiese tegnieke spesifiek hoof komponent analise (PCA) en parsiële kleinste kwadraat diskriminant analise (PLS-D) asook gelykvormigheidstoetsing bruikbare tegnieke is om te onderskei tussen kontrole (egte natuurlike) en vervalsde wyne ten opsigte van die byvoeging van geurmiddels. Beskrywende sensoriese analise kan ook nuttig gebruik word, alhoewel keuring en opleiding van paneellede tydrowend is.

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Agrárias, Programa de Pós-Graduação em Recursos Genéticos Vegetais, Florianópolis, 2015.
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A viticultura catarinense é uma atividade econômica em plena expansão e, nos últimos anos, vem buscando a melhoria dos vinhedos para produção de uvas e vinhos de alta qualidade. Nas regiões de altitude de Santa Catarina, a vitivinicultura ainda é muito recente e pouco se sabe sobre o comportamento ecofisiológico das plantas cultivadas. Dentre as variedades de maior importância econômica na região estão a Sauvignon Blanc e a Cabernet Sauvignon. Este estudo teve como objetivos caracterizar o crescimento vegetativo e os níveis de hormônios endógenos em ápices dos ramos, e caracterizar a diferenciação floral morfológica em gemas das videiras  Sauvignon Blanc e  Cabernet Sauvignon , cultivadas em São Joaquim-SC, no ciclo fenológico 2013/2014. A área experimental está localizada em um vinhedo comercial conduzido em sistema espaldeira, em altitude de 1.293m (28º15'13"S e 49º57'02"W). O delineamento experimental utilizado foi o completamente casualizado (DCC). Durante o ciclo foi realizado o acompanhamento da fenologia e das variáveis meteorológicas. As avaliações e coletas foram realizadas quinzenalmente. A partir da brotação foi acompanhada a evolução do crescimento vegetativo de 20 plantas por variedade, medindo-se o comprimento dos ramos da base até o ápice. Foram coletados aleatoriamente no vinhedo, ápices dos ramos das videiras para identificação e quantificação de hormônios endógenos (GA3 e GA4, AIA, ABA, cZ e tZ, SA e JA), através de Cromatografia Líquida de Ulltra Performance (UPLC) e Electrospray Ionization - Mass Spectrometry/Mass Spectrometry (ESI-MS/MS). Foram coletadas as cinco gemas basais de oito ramos por variedade para observação, em estereomicroscópio e microscopia eletrônica de varredura (MEV), dos estádios iniciais da diferenciação floral. Pode-se observar que o padrão de crescimento dos ramos foi similar para as duas variedades estudadas, sendo a maior taxa de crescimento observada no final da primavera, na primeira quinzena de dezembro (11/12/2013), após a plena floração. A paralisação do crescimento dos ramos ocorreu no verão, durante o período de maturação das bagas, no início de fevereiro (04/02/2014) para a Cabernet Sauvignon e em meados de fevereiro (18/02/2014) para a Sauvignon Blanc. A paralisação do crescimento foi induzida pela diminuição do fotoperíodo. As baixas temperaturas (<10°C) parecem estar associadas a uma resposta adicional no processo de aclimatação ao frio. As concentrações de ABA, SA e JA nos ápices dos ramos aumentaram durante a evolução do ciclo vegetativo, tendo suas máximas concentrações durante o período inicial de formação das bagas, antes da véraison. Os níveis hormonais nos ápices dos ramos apresentaram comportamento similar ao longo do ciclo para ambas as variedades. A  Cabernet Sauvignon apresentou concentrações maiores dos hormônios: ABA, SA e JA em comparação com a  Sauvignon Blanc . As concentrações de tZ não variaram significativamente ao longo do ciclo da  Cabernet Sauvignon e este fitormônio não foi quantificado para a  Sauvignon Blanc . Não foi possível quantificar os hormônios: GA3, GA4, AIA e cZ nos ápices de ambas as variedades. O início da diferenciação floral nas gemas ocorreu antes da floração para ambas as variedades, sendo 25 dias antes da plena floração (30/10/2013) para a  Sauvignon Blanc e 8 dias antes da plena floração (12/11/2013) para a  Cabernet Sauvignon . O primórdio de inflorescência totalmente desenvolvido foi identificado para a  Sauvignon Blanc antes da véraison, enquanto para a  Cabernet Sauvignon após a mudança de cor das bagas. Os resultados deste estudo possibilitaram a melhor compreensão do efeito das condições climáticas e do controle hormonal sobre o crescimento vegetativo da videira cultivada em São Joaquim-SC. Neste trabalho também identificou-se as fases fenológicas em que ocorreram os estágios iniciais da diferenciação floral das variedades na região.

Abstract : Santa Catarina viticulture is an expanding economic activity which is seeking in the last years to improve the vineyards for production of higher quality grapes and wines.The grapevine and wine production in Santa Catarina Highlands is still recent and little is known about grapes ecophysiological behavior. Sauvignon Blanc and Cabernet Sauvignon are among varieties of greater economic importance in this region. This study aimed to characterize the vegetative growth and the endogenous hormones levels in shoots apexes, and to characterize the morphological floral differentiation in grapevine buds of  Sauvignon Blanc and  Cabernet Sauvignon grown in São Joaquim/SC, at phonological cycle 2013/2014. Experimental area is located in a commercial vineyard conducted in VSP system (vertical shoot positioned), at 1.293m altitude (28º15'13"S and 49º57'02"W). The experimental design was completely randomized blocks. Phenology and weather variables were monitored during the season. Analysis and samples were taken every two weeks. From budburst on, shoot growth was assessed in 20 plants per variety, measuring the length from the base to the shoot apex. Aapexes of shoots were collected randomly for endogenous hormones (GA3 and GA4, AIA, ABA, cZ and tZ, SA and JA) identification and quantification using Ultra Performance Liquid Chromatography (UPLC) and Electrospray Ionization - Mass Spectrometry / Mass spectrometry (ESI-MS / MS). For floral differentiation analysis, five basal buds from eight shoots per variety were collected, and observations of the early stages of floral differentiation in stereomicroscope and scanning electron microscopy (SEM) were performed. It was observed similar pattern of shoot growth for both varieties, with higher growth rate in late spring, on the first half of December (12/11/2013), after full bloom. Shoot growth cessation occurred in the summer, during grape berry ripening, in early February (02/04/2014) for  Cabernet Sauvignon and in mid-February (18/02/2014) for  Sauvignon Blanc . Growth cessation was induced by photoperiod decrease. Low temperatures (<10°C) seem to be associated to an additional response in the process of cold acclimation. ABA, SA and JA concentration in apexes of the shoots increased during the course of the season, with maximum levels in the initial period of berry formation, before véraison. Hormone levels in shoot apexes showed similar behavior during cycle for both varieties.  Cabernet Sauvignon presented higher concentration of hormones (ABA, SA and JA) compared to  Sauvignon Blanc . For both varieties, changes in hormones levels in the apexes during the growth cycle had similar behavior. Concentrations of tZ did not present significant variation for  Cabernet Sauvignon and this plant hormone could not be quantified for  Sauvignon Blanc . It was not possible to quantify GA3, GA4, AIA and cZ in the apexes of shoots for both varieties. The beginning of floral differentiation in buds occurred before flowering for both varieties, 25 days before full bloom (10/30/2013) for 'Sauvignon Blanc' and 8 days before full bloom (12/11/2013) for  Cabernet Sauvignon . The fully development of inflorescence primordium was identified for 'Sauvignon Blanc' before véraison, while for  Cabernet Sauvignon it was after berries color change . Results of this study provided a better understanding of the effect of weather conditions and hormonal control over the vegetative growth of grapevine grown in São Joaquim-SC. In this work it was also identified the phenological phases when the early stages of floral differentiation of varieties in the region occurred.

Mestrado Vinifera Euromaster - Viticulture and Enology - Instituto Superior de Agronomia - UL / Institut National d'Etudes Superieures Agronomiques de Montpellier
In many ways New Zealand has become an ideal for a New World wine country. With the first commercial Sauvignon blanc only released in 1974, Sauvignon blanc fought its way to become not only the flagship of New Zealand`s wine industry, holding around 66 % of the country’s total grape production at the 2015 harvest, but also made its way to be recognized for its outstanding quality all over the world. For some critics, New Zealand Sauvignon blanc is arguably the best in the world and others called the Marlborough wine region the best place to grow Sauvignon blanc in New Zealand. Even though testimonies like that may be subjective as taste lies on the tongue of the beholder, New Zealand Sauvignon blanc clearly came a way plastered with success leading to an export value of $1.424 billion NZD in 2015. Key to this success is that the industry found a way to distance itself from its French archetype, world famous Sauvignon blanc originated from the Loire valley, and reinvented itself, introducing a unique winestyle that does not need to shy any comparison. In the heart of this winestyle aroma compounds of the thiol group play an important role. Derived during yeast activity during fermentation from non-odorous precursors found in grapejuice, the two most important thiols that have been related with Marlborough Sauvignon blanc are 3MH and 3MHA. These deliver exotic nuances reminiscent of grapefruit, passionfruit, gooseberry, guava and boxtree. Due to the high oxidability of thiols, several strategies have been adapted by the industry to preserve these key compounds and their non-odorous precursors during the processing of grapes, which includes harvesting, transportation, processing and storage. Although a lot of research has been carried out to further understand the relations between precursors, thiols and their preserving, and to be able to continuously contrast New Zealand Sauvignon blanc from competitors, many questions still remain unclear at the present day. One of them is the effect of juice turbidity on aroma development during fermentation. Research has revealed a broad idea on the positive and negative effects, caused by micronutrients and physical parameters of grape solids derived during process steps leading to juice extraction from the berries on fermentation kinetics and general aroma development. To my best knowledge no research has been published to the present day that focuses on the effect of juice turbidity on the thiol development and expression in Sauvignon blanc ferments. This masterthesis in hand, with the title “Effects of must turbidity on fermentative aroma development in Sauvignon blanc” is supposed to give an overview over the state of research on Sauvignon blanc with a further focus on the question about possible effects and practical applications of juice turbidity. Finally, this work tries to improve the small scale winemaking protocol of Plant and Food Research, Blenheim, where this research has been conducted.
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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.

Thesis (MScAgric)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: Sauvignon blanc wines have become progressively more important in the commercial market. Extensive research is being done in various countries to gain more understanding about the aroma compounds found in Sauvignon blanc wines and the interactions between them. Sauvignon blanc wines often have either have a green or tropical style. The green style is caused by the methoxypyrazines while the volatile thiols are important contributing compounds to the tropical style. Various international studies have focussed on measuring the chemical composition of Sauvignon blanc wines. However, more research is required on South African Sauvignon blanc wines. Little is known of the volatile thiols content of South African Sauvignon blanc wines, although the methoxypyrazine content has been extensively reported on. Although methoxypyrazines and volatile thiols are seen as the most important aroma compounds contributing to Sauvignon blanc character, other compounds contribute as well. Esters, monoterpenes and phenols have been found to influence Sauvignon blanc aroma and interact with the methoxypyrazines and volatile thiols. The complex interaction between the compounds responsible for the aroma of Sauvignon blanc wines are still not fully understood and further research is thus needed. The first part of the current study investigated the interaction between a specific methoxypyrazine and volatile thiol. Five different concentrations of 2-isobutyl-3- methoxypyrazine (ibMP) and 3-mercaptohexan-1-ol (3MH) were spiked in dearomatize, neutral Sauvignon blanc wine. The single compounds as well as every possible combination of the range of concentrations were evaluated using sensory descriptive analysis. It was found using various statistical approaches that ibMP suppressed the tropical attributes associated with 3MH and that 3MH suppressed the green attributes that correlated with ibMP. The concentrations at which the suppression occurred and the degree of suppression was different for each attribute. The second part of the current study focussed on commercial South African Sauvignon blanc wines. Sensory descriptive analysis and chemical analysis were used to assess the wines and measure the volatile thiol and methoxypyrazine concentrations. The concentrations of volatile thiols and methoxypyrazines were found to be in line with international Sauvignon blanc wines. It was also shown for the first time that the mutually suppressive trend between the volatile thiols and methoxypyrazines can be seen in commercial Sauvignon blanc wines as well. Future work is needed to fully understand the complex interaction between the various compounds in Sauvignon blanc wines. Further research could focus on investigating the mechanism of interaction between the volatile thiols and methoxypyrazines as well as other aroma compounds.
AFRIKAANSE OPSOMMING: Sauvignon blanc-wyne word toenemend belangriker in die kommersiële mark. Omvattende navorsing word in etlike lande gedoen om meer begrip te ontwikkel van die aromaverbindings wat in Sauvignon blanc-wyne teenwoordig is, asook van die interaksies tussen hulle. Sauvignon blanc-wyne het in baie gevalle óf ’n groen óf ’n tropiese styl. Die groen styl word veroorsaak deur metoksipirasiene, terwyl die vlugtige tiole belangrike bydraende verbindings is wat aanleiding gee tot die tropiese style. Verskeie internasionale studies het reeds gefokus op die meet van die chemiese samestelling van Sauvignon blanc-wyne, maar meer navorsing is nodig oor Suid-Afrikaanse Sauvignon blanc-wyne. Min is bekend oor die inhoud van vlugtige tiole in Suid-Afrikaanse Sauvignon blanc-wyne, hoewel daar reeds op groot skaal oor die metoksipirasieninhoud verslag gedoen is. Hoewel metoksipirasiene en vlugtige tiole die belangrikste aromaverbindings is wat tot Sauvignon blanc-karakter bydra, is daar ook ander verbindings wat ’n bydrae maak. Esters, monoterpene en fenole het almal ’n invloed op Sauvignon blanc-aroma en reageer op die metoksipirasiene en vlugtige tiole. Die komplekse interaksie tussen die verbindings wat vir die aroma van Sauvignon blanc-wyne verantwoordelik is, word nog nie volledig begryp nie en verdere navorsing is nodig. Die eerste deel van die huidige studie het die interaksie tussen ’n spesifieke metoksipirasien en vlugtige tiol ondersoek. Vyf verskillende konsentrasies van 2-isobutiel-3-metoksipirasien (ibMP) en 3-merkaptoheksaan- 1-ool (3MH) is by ontgeurde, neutrale Sauvignon blanc-wyn gevoeg. Die enkel verbindings, asook elke moontlike kombinasie van die reeks konsentrasies, is deur middel van beskrywende sensoriese analise geëvalueer. Daar is met behulp van verskillende statistiese benaderings gevind dat ibMP die tropiese eienskappe wat verband hou met 3MH onderdruk het, terwyl 3MH die groen eienskappe wat verband hou met ibMP onderdruk het. Die konsentrasies waarteen die onderdrukking plaasgevind het en die vlak van onderdrukking het vir elke eienskap verskil. Die tweede deel van die studie het gefokus op kommersiële Suid-Afrikaanse Sauvignon blancwyne. Beskrywende sensoriese analise en chemiese analise is gebruik om die wyne te assesseer en die konsentrasies van vlugtige tiole en metoksipirasiene te meet. Die konsentrasies vlugtige tiole en metoksipirasiene was in lyn met dié van internasionale Sauvignon blanc-wyne. Daar is ook vir die eerste keer gewys dat die wedersyds onderdrukkende tendens tussen die vlugtige tiole en metoksipirasiene ook in kommersiële Sauvignon blanc-wyne gevind word. Toekomstige werk sou kon fokus op ’n begrip van die komplekse interaksie tussen die verskillende verbindings in Sauvignon blanc-wyne. Verdere navorsing sou ook kon fokus op ’n ondersoek van die meganisme van interaksie tussen die vlugtige tiole en metoksipirasiene, sowel as ander aromaverbindings.
The South African Wine Industry (Winetech), THRIP and the NRF for financial support

Thesis (MScAgric)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: Acids are one of the major components that originate largely from the berry, that are found in wine, and that influence the sensory perception. The presence of organic acids in adequate concentrations in the grape berry, of which tartaric- and malic acid are the main organic acids present, is important as this determines the potential of a must to produce a good and stable wine. The effect of temperature on the organic acid content of the must is widely discussed with higher temperatures in general being associated with lower quantities of organic acids present in the juice, and lower temperatures during ripening associated with higher quantities, specifically in the case of malic acid. Due to the topographical diversity of the Stellenbosch Wine of Origin district and the closeness of the ocean and the occurrence of sea breezes, the mesoclimate differs greatly over short distances. Sixteen sites, consisting of eight Sauvignon Blanc and Cabernet Sauvignon sites respectively, were selected from a broader terroir study site network. Three vintages with complete climatic datasets were selected for vintage comparisons. Climate in the study area was monitored on differing scales, and data from a weather station network, as well as from mesoclimatic dataloggers within the sites were available. The available data was firstly compared to determine the variability of the data, not only between the two climatic scales, but also between the sites. Different climate classification indices and parameters available in literature were thereafter compared and evaluated for the best representation in this area. The Huglin index was found to be a better representation regarding the thermal climatic indices. Due to the great differences between temperatures noted for the mesoclimatic loggers and the nearest automatic weather station, the use of mesoclimatic logger data was preferred, and is advised in future studies where this scale of data is available. Malic and tartaric acid has a definite synthesis period up until véraison, after which the content of tartaric acid remains constant in the berry and the content of malic acid decreases until harvest due to mainly respiration. The temperature data was therefore separated in a synthesis period from flowering to véraison, and a ripening period from véraison to harvest. In this study, clear differences were firstly seen in the climate as expected, not only between sites per vintage, but in addition between vintages and between vintages per site. The phenological differences between the sites could be largely attributed to the differences in temperature as phenology and temperature was found to be highly correlated in this study. Differences in the ripening parameters were noticed in addition to the contents of the organic acids between sites, although no definite contribution of temperature was shown to affect the contents of these compounds at either véraison or harvest. These differences may be attributed to other factors such as the soil water content and the canopy architecture. In addition, these factors all contribute in differing percentages to the differences found in the contents per site. It was found though that temperature can be used as an indicator of the organic acid content in the grape berry, considering that the temperature data is available on a mesoclimatic scale, separated in a synthesis and period of degradation, and the number of hours within the temperature thresholds are determined. Differences seen in the organic acid contents can however not only be attributed to the differences in topography and the temperature as discussed in this study.
AFRIKAANSE OPSOMMING: Sure is belangrike druifkomponente wat grootliks hul oorsprong in die korrel het, in die wyn voorkom, en die sensoriese persepsie van die wyn beïnvloed. Die voorkoms van organiese sure in genoegsame konsentrasies in die korrel, waarvan wynsteensuur en appelsuur die hoof organiese sure is, is belangrik aangesien dit die potensiaal van die sap om ʼn goeie en stabiele wyn te produseer, bepaal. Hoe temperatuur die inhoud van organiese sure in die druiwesap affekteer is gereeld onder bespreking, met hoër temperature in die algemeen geassosieer met ʼn laer inhoud van organiese sure, terwyl laer temperature geassosieer word met ʼn hoër inhoud van organiese sure in die sap, veral in die geval van appelsuur. As gevolg van die topografiese diversiteit van die Stellenbosch Wyn van Oorsprong distrik, asook die nabyheid van die oseaan met die gepaardgaande voorkoms van die seebries, verander die mesoklimaat aansienlik oor klein afstande in hierdie area. Vir die studie was sestien wingerde, wat bestaan het uit agt Sauvignon Blanc en agt Cabernet Sauvignon wingerde, geselekteer vanuit ʼn groter terroir studie. Verder was drie seisoene, met volledige klimaatsdatastelle, geselekteer vir die vergelyking van data tussen die seisoene. Klimaat was op verskillende skale binne die studie area gemonitor en data van ʼn weerstasie netwerk, sowel as van mesoklimaat dataversamelaars binne die wingerde, was beskikbaar. Die beskikbare datastelle was vergelyk, asook geëvalueer, om die mees verteenwoordigende datastel vir die area te bepaal. Met die oorweging van die termiese indekse was daar gevind dat die Huglin indeks beter verteenwoordigend van die area was. Verder, as gevolg van die groot verskille wat gevind is tussen die temperature gemeet met die mesoklimaat dataversamelaars en die naaste outomatiese weerstasie, was daar besluit dat die gebruik van die mesoklimaat data verkies is en is dit ook aan te beveel vir die gebruik in toekomstige navorsing indien die tipe data beskikbaar is. Wynsteen- en appelsuur het beide ʼn definitiewe sintese periode tot en met véraison, waarna die hoeveelheid wynsteensuur in die korrel relatief konstant bly en die hoeveelheid appelsuur afneem hoofsaaklik as gevolg van respirasie. Die temperatuur data was dus verdeel in ‘n periode van sintese vanaf blom tot en met véraison, en ʼn rypwordingsperiode vanaf véraison tot en met oes. In hierdie studie was daar eerstens groot verskille waargeneem in die klimaat soos wat daar verwag is. Hierdie verskille was nie net waargeneem as tussen die seisoene nie, maar ook tussen die wingerde binne ʼn seisoen. Die fenologiese veskille tussen die wingerde wat ook waargeneem is, kon hoofsaaklik aan die verskille in die temperatuur toegeskryf word en ʼn goeie korrelasie tussen temperatuur en fenologie is opgemerk. Merkwaardige verskille in die rypwordingsparameters, asook in die inhoud van die organiese sure, was waargeneem, alhoewel die bydrae van temperatuur op die inhoud van hierdie komponente by véraison of oes nie as definitief getoon is nie. Dit kan toegeskryf word aan die bydrae van ander faktore, soos byvoorbeeld die grondwaterinhoud en die lowerargitektuur, op die inhoud van hierdie komponente. Die addisionele faktore dra egter in verskillende persentasies by tot die verskille waargeneem tussen die wingerde.

La mise au point de techniques de fractionnement des moûts de Sauvignon blanc par chromatographie de partage centrifuge et par chromatographie Flash, a permis de mettre en évidence la présence de deux « nouvelles » formes précurseurs du 3SH (le S-3-(hexan-1-al)-glutathion et l'acide S-3-glutathionyl-hydroxyhexanesulfonique). L’ensemble de ces résultats a permis de confirmer la contribution majeure des S-conjugués au potentiel en 3SH des moûts. Le S-3-(hexan-1-ol)-L-cystéine, le S-3-(hexan-1-ol)-glutathion ainsi que les deux nouvelles formes identifiées, permettent d’expliquer près de 65% du 3SH libéré dans les vins. Par ailleurs, nous avons montré que l’ensemble des formes précurseurs appartenait à la même voie d’assimilation de la levure et que le S-3-(hexan-1-ol)-L-cystéine est un intermédiaire indispensable à la biotransformation des S-conjugués au glutathion, précurseurs du 3-sulfanylhexanol. De plus, le pourcentage de biotransformation des différents S-conjugués en 3SH semble directement lié à leur position dans le flux métabolique
The development of fractionation techniques in Sauvignon Blanc musts such as centrifugal partition chromatography and flash chromatography, permitted to identify two precursor forms of 3-sulfanylhexanol : the S-3-(hexan-1-al)-glutathione, and the S-3-glutathionyl-hydroxy hexanesulfonic acid. These results confirmed the major contribution of S-conjugates in the potential liberation of 3-sulfanylhexanol in musts. The two newly identified forms along with S-3-(hexan-1-ol)-L-cysteine and S-3-(hexan-1-ol)-glutathione, explain up to 65% of the total release of 3-sulfanylhexanol. Futhermore, we showed that all precursor forms belonged to the same assimilation pathway of yeast and the S-3-(hexan-1-ol)-L-cysteine is an essential intermediate in the metabolism of S-glutathione conjugates, which is a precursor of 3-sulfanylhexanol . Finally, the biotransformation percentage of different S-conjugates of 3-sulfanylhexanol seems directly related to their position in the metabolic flow

In this chapter, an overview of the impact of phytosanitary treatments on the vineyard microbiome is provided, together with the results of the research we conducted. The studied plant material consisted of grapevine from the cultivars Sauvignon blanc and Cabernet Sauvignon, cultivated within the plantation of the Research Station for Viticulture and Enology from Murfatlar, Romania. For each cultivar, a treated plot and an untreated plot were established. For each of those, the phyllosphere microbiota was quantified using the epifluorescence microscopy method, followed by automated image analysis using CellC software. At the same time, the soil fungal diversity was evaluated in three stages during the year 2021, using microscopic morphological criteria. The results give useful information regarding the phytosanitary state of the studied plant, as well as the short-term effects produced by the ceasing of pesticide application on the grapevine microbiota.

Esca is an increasing threat to global viticulture causing significant losses by reducing yields, declining or wilting vines, and shortening the productive life of vineyards. Recent findings indicate that the disease may also affect the quality of grapes and the chemical composition of musts and wines. However, more research in this field is needed. Esca seems to affect the ripening process of grapes resulting in lower sugar content, higher acidity, and increased nitrogen concentrations. Regarding polyphenolic compounds, reduction on the concentrations of (+)-catechin, (−)-epicatechin, anthocyanins, and tannins has been observed due to the alteration of flavonoid metabolism. Esca is a complex-chronic disease, where several fungal pathogens act simultaneously or successively, to cause necrosis to the vascular tissues of grapevines by blocking the xylem vessels and by producing enzymes and phytotoxic metabolites. As genotype affects stress response, specific Vitis vinifera cultivars present higher levels of resistance to the disease than others. There is evidence that varieties such as Merlot, Grenache Rouge, and Roussanne are relatively resistant, compared with more susceptible Cabernet Sauvignon, Mourvèdre, Sauvignon Blanc, and Semillon. Another main objective of the current work was to investigate the possible effects of climate change on Esca development and propose appropriate control strategies.

It is widely claimed that growing the vines that will produce good wine grapes starting from seed is difficult. In part, as noted above, this is apparently due to the presence of different alleles expressed differently as a function of environmental factors. As a consequence, most wine is produced from grapes arising from a graft of a vine that already produces desirable product. However, it is possible to plant seeds to generate vines— although the product is not always what is expected! The fact that parent varieties (the flower of one parent and pollen of another) will generally produce a variety different from either parent is generally sought to be avoided in com¬mercial enterprise. However, since grape flowers (as will be discussed in Chapter 12) are often found as tight clusters, hermaphroditic reproduction either naturally or by intervention can be effective. Adventures in crossing, such as with the Vitis vinifera varieties Cabernet franc and Sauvignon blanc can be profitable. They are reported to have led to the formation of Cabernet Sauvignon. The grape seed needs to germinate. Germination is evidenced by the forming of the plant within the seed and the opening of the seed coat to produce a seedling (Figure 2.1). The plant embryo responds, as dictated by the genome, to the warmth of the soil and the availability of water, and continues to grow from the first cell division until the plant sprouts. It is not uncommon for seeds of many species to have set a genetically dictated timer. The setting of the timer may, for example, require that the ground be frozen and subsequently thawed (a process called vernalization). Once moistened, by a thaw or rain, the dry seed takes up water that passes through channels in cell walls and membranes (the inside of the cell being drier than the outside) that apparently open in response to the “timer” and in response to soil constituents. Ions found in the soil are washed in with the water. The water and nutrients in the soil are now available to put the enzymes and their cofactors, previously lying fallow in the seed, to work.

The aim of the research was to assess the harmfulness of alternariosis on various genotypes of grape varieties. The difference in the intensity of development and spread of alternariosis in intra- and interspecific hybrids of grapes was 78.7 and 75.4 % at the end of the growing season. No harmful effect of alternariosis on the yield and quality of grapes of intraspecific hybrid (‘Sauvignon Blanc’ variety) was detected. Strong development on an interspecific hybrid (‘Bianca’ variety) led to the yield decrease by 48.6 %, and sugar content reduction – by 7.7 %.