Effect of storage temperature on the chemical composition and sensory profile of Sauvignon Blanc wines

Background and Aims: Most white wines lose fresh and fruity characteristics, associated with volatile esters, during ageing in the bottle. A higher storage temperature accelerates these changes. The aim of this study was to examine the influence of storage temperature on the chemical and sensory properties of Sauvignon Blanc wines. Methods and Results: Three commercially bottled Sauvignon Blanc wines from the 2008 and 2009 vintages were stored at 5, 10, 18°C and at room temperature for 12 months. Wines stored at warmer temperatures (18°C and room temperature) contained lower concentrations of acetate esters, including the prominent varietal thiol 3MHA, and ethyl esters of fatty acids, than the wines stored at cooler temperatures (5 and 10°C). A warmer temperature accelerated the rate of ester hydrolysis. Conversely, the concentrations of ethyl esters of branched acids were higher in wines stored at the warmer temperatures. The sensory profile of the wines was assessed after 12 months for the two 2008 wines and after 8 months for the 2009 wine. The wines stored at cooler temperatures were characterised by higher fruity and fresh vegetal aromas, whereas the wines stored at warmer temperatures exhibited the opposite sensory profile, with dominant woody/smoky/oaky, buttery, flinty and canned asparagus notes. Conclusions: These results indicate that temperature‐dependent hydrolysis processes are critical for Sauvignon Blanc aroma stability during the first year in the bottle. Significance of the Study: Cool storage temperature conditions can significantly increase the shelf‐life of Sauvignon Blanc wines by preserving their fruity and fresh green characters.     

Free and Bound Volatile Secondary Metabolites of Vitis Vhifera Grape cv. Sauvignon Blanc

Free volatiles, and those hydrolytically released from glycosidic forms, were analyzed for Sauvignon Blanc juices from three successive vintages. Most of the 213 compounds identified were in one of the bio-genetic categories: norisoprenoids, benzene derivatives, monoterpenes or aliphatics. Several have not been previously reported as grape components. Monoterpenes were in lower concentration than normally found in floral grape varieties, but at higher levels than reported in Chardonnay juices. A notable proportion (40–50%) of the bound monoterpenes were monocyclic. Hydration of α-terpineol at pH 3 gave c-4-(1-hydroxy-1-methyIethyl)-1-methyl-r-1-cyclohexanol (cis-p-men-thane-1,8-diol) and t-4-(1-hydroxy-1-methylethyl)-1-methyl-r-1-cy-clohexanol (trans-p-menthane-1,8-diol) as the main products and a low yield of t-4-(1-methylethyl)-r-1-methylcyclohexane-1,4-diol (trans-p-menthane-1,4-diol). These were confirmed as major components of the acid hydrolysates of the bound fraction.     

Effect of polyphenols on the perception of key aroma compounds from Sauvignon Blanc wine

Background and Aims:  Sensory wine research has mainly focused on the role of volatile compounds and their contribution to the aroma profile. Wines also contain polyphenolic compounds, which are not volatile. This research begins to investigate the interactions of volatile and non-volatile wine compounds and the consequential effects on sensory perception of aroma.
Methods and Results:  Trained panellists of this study measured the perception of four aroma compounds (isobutyl methoxypyrazine, 3-mercaptohexanol, 3-mercaptohexanol acetate and ethyl decanoate) in wine. Panellists assessed the four compounds in combinations with three polyphenols (catechin, caffeic acid and quercetin) commonly found in white wine. The perception of isobutyl methoxypyrazine, 3-mercaptohexanol and ethyl decanoate was largely suppressed by the added polyphenols, while the perception of 3-mercaptohexanol was accentuated with the addition of caffeic acid. Of the three polyphenols, only catechin had a slight effect of accentuating the mercaptohexanol acetate perception.
Conclusions:  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.
Significance of the Study:  Understanding these interactions can assist winemakers in managing polyphenol levels to optimize selected volatile compounds to achieve desirable aroma profiles.     

Influence of fruit ripeness and juice chaptalisation on the sensory properties and degree of typicality expressed by Sauvignon Blanc wines from Marlborough,New Zealand

Background and Aims: Interest in the typical sensory properties exhibited by Sauvignon Blanc wines from Marlborough, New Zealand, is increasing. Although critical from a winemaking standpoint, there is a significant lack of data concerning the extent to which these typical sensory characteristics are affected by fruit ripeness at harvest and juice chaptalisation. Methods and Results: Experimental Marlborough Sauvignon Blanc wines fermented from fruits at three different ripeness stages, with or without juice chaptalisation, were assessed by a panel of wine professionals from Marlborough. Results suggest that the balance between green and fruity ripe flavours that makes a Marlborough Sauvignon Blanc typical of its style would originate from the fruit ripeness at harvest. We also report that juice chaptalisation can modulate the wines' taste and mouthfeel properties and significantly affect their typicality as Marlborough Sauvignon Blanc. Conclusions: The production of Marlborough Sauvignon Blanc wines that well represent their specific style relies primarily on the ripeness of the fruit at harvest, the impact of which can be modulated by juice chaptalisation. Significance of the Study: This is the only study that has considered fruit ripeness and juice chaptalisation as two factors that condition the sensory properties and degree of typicality expressed by Marlborough Sauvignon Blanc wines.     

Pre‐budburst temperature influences the inner and outer arm morphology,phenology, flower number,fruitset, TSS accumulation and variability of Vitis vinifera L. Sauvignon Blanc bunches

Background and Aims: Inflorescence morphology, flower formation and subsequent fruit development of grapevines are influenced by genetic, environmental and cultural practices. While the effect of temperature on inflorescence primordia number per bud is documented, its effect during dormancy and budburst (BB) on floral development is less clear. In our study, winter dormant buds were passively heated for different periods of time from mid‐winter (July) to BB (October). Methods and Results: Individual canes were heated pre‐BB for different periods in polyethylene tunnels. Heating during winter dormancy had no effect on the number or position of inflorescences on the shoot, or on the type of structure occurring at the outer arm position of the inflorescence. Heating buds for either July or August to BB advanced the date of BB and the start date of flowering by 12–14 and 14 days, respectively, compared with that of the unheated Control treatment. There was a significant (P < 0.05) negative correlation between the mean temperature 12 days pre‐BB and flower number per shoot. The time between 50% flowering and the fruit TSS reaching 14°Brix was not influenced by winter heating or the date of flowering; the difference in this time interval, however, between the inner and outer arm components increased as shoot node number increased. Conclusions: Flower number per inflorescence had the greatest influence on the proportion of fruitset. The date of flowering of the outer arm was later at higher inflorescence positions on the shoot and later than that of the inner arm. Likewise, the outer arms of bunches higher up the shoot took longer from flowering to accumulate a fruit TSS of 14°Brix. Significance of the Study: Much of the within‐vine variability in berry composition at harvest can be attributed to the position of bunches on the shoot and the presence of an outer arm. The outer arm on apical bunches took significantly longer to progress from flowering to a fruit TSS of 14°Brix, suggesting that removal would significantly reduce within‐vine fruit variability.     

Distribution of varietal thiol precursors in the skin and the pulp of Melon B. and Sauvignon Blanc grapes

In order to examine varietal thiol precursors in both the skin and the pulp of grapes, two grape varieties, Melon B. and Sauvignon Blanc, were considered. We found that cysteinylated and glutathionylated precursors of 3-mercapto-1-hexanol and 4-methyl-4-mercapto-2-pentanone were preferentially in skin. In the Sauvignon Blanc variety, precursors were detected both in the skin and the pulp, while in Melon B., only S-3-(1-hexanol)glutathione was detected in pulp, any other precursors being exclusively found in skin. During an industrial pressing cycle, extraction of thiol precursors was enhanced at the end of the cycle (highest pressures), thus producing more varietal thiols in the resulting wines. Cold prefermentation skin contact did not influence the concentration of the measured precursors in Sauvignon Blanc must. Nevertheless, the release of thiol in resulting wines increased significantly between 1 and 7 days of cold prefermentation skin contact. This increase could be due to the formation of other thiol precursors, such as S-3-(1-hexanal)glutathione or S-3-(1-hexanal)cysteine, during prefermentative operations.     

长相思葡萄生长发育过程中理化指标及氨基酸含量分析

该试验以宁夏银川的张裕摩塞尔酒庄的长相思葡萄（Sauvignon Blanc）为试材,主要测定葡萄浆果生长发育7个时期葡萄的糖、酸和氨基酸含量等主要品质指标,并对果实品质进行主成分分析（PCA）。结果表明,可溶性固形物含量和百粒质量、pH值随着长相思葡萄果实的发育呈上升趋势;可滴定酸、总酚和单宁含量呈下降趋势。从葡萄浆果共检测出16种氨基酸组分,其中胱氨酸从花后40 d到花后90 d呈缓慢下降趋势,在成熟时（花后105 d）增长至130.52 mg/L;甲硫氨酸、苏氨酸、酪氨酸、异亮氨酸和赖氨酸含量在发育过程中保持相对稳定,亮氨酸则从花后40 d的67.77 mg/L持续增长至成熟时的336.75 mg/L,其他9种氨基酸的含量从花后40 d到花后90 d呈增长趋势,在成熟前略有下降。精氨酸与脯氨酸含量的比值从花后50 d快速增加,成熟时达到最大值（5.67）。PCA结果表明长相思葡萄在不同发育时期的氨基酸含量差异较大。     

Contents of 3‐alkyl‐2‐methoxypyrazines in musts and wines from Vitis vinifera variety Cabernet Sauvignon: influence of irrigation and plantation density

The influence of irrigation and plantation density on the methoxypyrazine content in musts and wines has been studied. Samples were monitored throughout grape ripening and wine‐making. 3‐Isobutyl‐2‐methoxypyrazine, 3‐sec‐butyl‐2‐methoxypyrazine and 3‐isopropyl‐2‐methoxypyrazine were identified and quantified. Samples from irrigated vines had significantly higher average contents of 3‐isobutyl‐2‐methoxypyrazine than samples from non‐irrigated plants. Average levels of this compound were also higher in samples from vines with the higher plantation density. Copyright © 2005 Society of Chemical Industry     

Influence of retained cane number and pruning time on grapevine yield components,fruit composition and vine phenology of Sauvignon Blanc vines

Background and Aims: Traditionally, the start of cane pruning is delayed until after leaf fall, when carbohydrate accumulation and cane maturity are complete. However, by starting immediately after harvest, the period for pruning may be increased by at least 4 weeks, reducing peak labour demands. Trials were conducted to investigate the consequences of various pruning times on vine phenology and yield. Methods and Results: Vines were pruned using 2‐ or 4‐canes at one of four times during the winter from shortly after harvest to just before bud break in the spring. Pruning shortly after harvest caused no significant adverse effects on vine phenology or productivity. Pruning just before bud break delayed vine development. Stored total carbohydrate concentrations in the trunk were unaffected by pruning time or cane number retained after pruning. Conclusions: Carbohydrates accumulated in the trunks of grapevines to adequate levels by harvest and any post‐harvest photosynthesis and/or cane maturation that may be occurring at this time had little effect on subsequent vine growth and development. Pruning shortly before bud break delayed bud break and may be an advantage where vines are at risk to spring frosts. Significance of Study: In cool climates where leaves senesce shortly after harvest, pruning immediately after harvest will have no adverse effects on subsequent vine phenology or yield, but will extend the period available to prune the vines, reducing the peak labour demand in the vineyard. Pruning late, slightly delays bud break potentially providing greater tolerance to late spring frosts.