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Wine flavor and quality are determined by the assessment of multiple sensory stimuli, including aroma, taste, and mouthfeel. It is therefore important to consider the contribution of as many metabolites as possible when attempting to relate wine composition to quality. In this study, partial least squares regression of the volatile (untargeted headspace solid-phase microextraction coupled with gas chromatography time-of-flight mass spectrometry), non-volatile (untargeted reverse-phase ultra-high-performance liquid chromatography mass spectrometry), and combined metabolite profiles were used to predict Pinot Noir wine quality ratings as assessed by experts. Non-volatile metabolite profiles predicted wine quality ratings better than volatile metabolite profiles, suggesting that the non-volatile composition of Pinot Noir wines contributes to quality perception to a greater extent than the volatile composition. This was underscored by descriptive sensory analysis, which found that taste and mouthfeel attributes were better correlated with wine quality ratings than aroma attributes. Important predictors of Pinot Noir wine quality were also characterized. Some new relationships between wine metabolites and quality ratings were found: dipeptides and unsaturated fatty acids were positively related to Pinot Noir wine quality, while N-(3-methylbutyl)acetamide and xanthine were negatively associated.

Vine genetics, fruit maturity, region and vineyard are perceived as factors that strongly influence Pinot noir grape and wine composition. Our study aims to understand the relationship between grape (and ultimately wine) composition and the physical appearance and performance characteristics of a vine (i.e. vine ideotype). Our experimental approach controlled these variables by studying within-block differences in vine performance across multiple seasons and vineyards. Grapes were sourced at commercial harvest from 20 single vines from 12 vineyard sites in three Pinot noir growing regions (Central Otago, Martinborough and Marlborough) of New Zealand.Across three vintages yields ranged from 0.1 kg to 6.3 kg per metre, but there was no general relationship between yield and berry soluble solids. On a vine by vine basis normalised yields did not correlate among seasons. Berry extract colour measures were, on average, three-fold higher in 2019 than in 2018.Principal Component Analysis has indicated that vintage dominated berry composition effects that might otherwise be associated with yield per vine, region and vineyard. The extent of the variation in performance of the same vines between seasons largely excludes factors that are stable between seasons as primary causes. Changes in management of the same vine from year to year appeared the most likely contributors to variation. We have derived highly significant negative linear relationships between vine yield class and the frequency of vines that were within a benchmark specification established for icon vines, providing evidence of the quality risk associated with higher yield. The results also indicate that a proportion of vines meet the benchmark specification at higher yields. From results to date we can further our research confident in the knowledge that factors such as vine yield, region or vineyard are, in themselves, unlikely to be the principal drivers of major differences in Pinot noir grape and wine composition.

Seasonal differences in weather conditions cause marked variation in grapevine yield. However, quantitative relationships between various yield components and climatic factors at field scales are still lacking. By using a long-term field trial, we quantified the correlation between weather conditions during the key development stages and the yield components of Vitis vinifera L. Sauvignon blanc growing under cool-climate conditions. A long-term phenology and yield monitoring trial using both two-cane and four-cane trained vertically shoot positioned (VSP) Sauvignon blanc vines was established in four vineyards in Marlborough, New Zealand in 2004. Phenology, bunch number, berry mass, yield and meteorology records were collated. A multivariable mixed linear model was used to assess the relationship between various yield components and weather conditions. The critical periods for each yield component and weather factor were optimised based on the maximum likelihood returned from the mixed linear model. The optimised critical periods of temperature for all yield components occurred mainly before 50 % flowering either in the previous season (during inflorescence initiation) and the current season, indicating the importance of the pre-flowering period on yield formation. Out of all weather factors, maximum daily temperature had the largest effect on bunch number and overall yield and strongly influenced berry number and bunch mass. Rainfall near flowering time had a negative effect on berry mass and bunch mass, but post-flowering rainfall had a strong positive effect. The statistical model explained 60 to 85 percent of the seasonal variations in bunch number, berry number, berry and bunch mass and yield per vine.

Sesquiterpenes are an important class of molecules, with roles ranging from pollination and signalling to defense mechanisms. Despite their apparent importance, the limited number of commercial standards has hindered their study and precise quantification. Herein, we report the syntheses of fourteen labelled sesquiterpenes with a high level of deuterium incorporation (>95%) for applications in MS-based studies.

Grape marc, also known as grape pomace, is an underutilized biowaste composed predominantly of grape skin and seeds that is produced as a byproduct of winemaking on the million-tonne scale annually. The most important high-value current use of grape marc is in the production of oenological tannins, widely used additives in the food and beverage industry. More commonly, grape marc is simply either disposed of or used as feed or fertilizer. With recent evidence showing that extracts enriched in grape tannins contain significant amounts of the thiol precursors Cys-3SH and GSH-3SH and the possibility that these could influence food and beverage aroma, it was decided to investigate grape pomace extraction procedures in order to try to define extraction protocols that could maximize the recovery of these compounds from grape marc. Should such an extraction protocol be shown to be commercially viable, this could lead to further utilization of material that would otherwise be disposed of. Two thiol precursors and...