Impact of Acetaldehyde Addition on the Sensory Perception of Syrah Red Wines.

Two experimental Syrah red wines with different polyphenol contents were used to study the impact of acetaldehyde addition on olfactory perception. Free acetaldehyde levels were measured in red wine by Head Space-Gas Chromatography-Mass Spectrometry (HS-GC-MS) to determine the acetaldehyde combination levels for those wines. Significant differences were observed for both sensory threshold and acetaldehyde combination for the wines. A descriptive sensory analysis of the wines was then performed by using a trained panel and a Hierarchical-Check-All-That-Apply (HCATA) analysis of the wines with or without acetaldehyde addition. The results show that classical cited sensory descriptors for acetaldehyde (overripe apple and oxidized apple) varied significantly between the control wines and those with acetaldehyde addition. Non-acetaldehyde related descriptors (fresh vegetable, fresh flowers, cocoa, and meat juice) were also significantly impacted in the samples with increasing acetaldehyde additions. This suggests possible interactions between acetaldehyde and other volatile compounds that can create antagonistic or synergistic effects between the molecules or at the olfactory receptor level.

Study of the relationship between red wine colloidal fraction and astringency by asymmetrical flow field-flow fractionation coupled with multi-detection.

Macromolecules including condensed tannins and polysaccharides impact wine taste and especially astringency. Asymmetrical Flow-Field-Flow-Fractionation (AF4) coupled to UV detection (UV), multi-angle light scattering (MALS) and refractive index detection (dRI) has been proposed to separate red wine colloids. The present work aimed at relating AF4-mutidetection profiles with red wine astringency. Fifty commercial red wines characterized by a trained sensory panel were analysed by AF4-UV-MALS-dRI and UV-visible spectroscopy. The analytical data set was built by selecting the three variables most predictive of the astringency score from each table (UV, dRI, MALS, Mw distribution, and UV-visible spectra of whole wine, permeate and retentate A4F fractions) and analysed by principal component analysis. Red wine astringency was more related to variables extracted from the AF4 data than to UV- absorbance of the wine or permeate, confirming the relevance of AF4-multidetection for analysis of the colloidal fraction involved in this perception.

Development of a methodology to study typicity of PDO wines with professionals of the wine sector.

BACKGROUND: Today, many agricultural products claiming a link to their origin and typicity receive a warm welcome on the market. Nevertheless, the notion of typicity is blurred for consumers and needs to be objectified for communication purposes. This study aims at formalizing a methodology for studying typicity of terroirs, with PDO wines as an example, using a participatory approach with professionals of the wine sector from terroirs, using focus group and tasting. The vision of typicity of terroirs by professionals outside of these terroirs has been studied by a free word association task. RESULTS: This study allowed a clear distinguishing of the typicity of the studied terroirs. Professionals from terroirs identified the global conceptual typicity of their terroirs using various factors, mainly soil, geography and grape variety, whereas professionals outside terroirs expressed their visions of terroirs by reputation or sensory characteristics of wines. Tasting results showed a discrimination of wines based on their typicity and highlighted descriptors involved in sensory perceptual typicity for each studied terroir. CONCLUSIONS: Professionals from terroirs share a common vision of their typicity and identify more typicity factors than professionals outside terroirs. Sensory typicity has been highlighted for five of the six terroirs studied, according to the various descriptors. The study of two populations, from and outside terroirs, shows the gap between the typicities identified by professionals from terroirs and those perceived by professionals outside terroirs. © 2020 Society of Chemical Industry.

Models based on ultraviolet spectroscopy, polyphenols, oligosaccharides and polysaccharides for prediction of wine astringency.

Astringency elicited by tannins is usually assessed by tasting. Alternative methods involving tannin precipitation have been proposed, but they remain time-consuming. Our goal was to propose a faster method and investigate the links between wine composition and astringency. Red wines covering a wide range of astringency intensities, assessed by sensory analysis, were selected. Prediction models based on multiple linear regression (MLR) were built using UV spectrophotometry (190-400 nm) and chemical analysis (enological analysis, polyphenols, oligosaccharides and polysaccharides). Astringency intensity was strongly correlated (R(2) = 0.825) with tannin precipitation by bovine serum albumin (BSA). Wine absorbances at 230 nm (A230) proved more suitable for astringency prediction (R(2) = 0.705) than A280 (R(2) = 0.56) or tannin concentration estimated by phloroglucinolysis (R(2) = 0.59). Three variable models built with A230, oligosaccharides and polysaccharides presented high R(2) and low errors of cross-validation. These models confirmed that polysaccharides decrease astringency perception and indicated a positive relationship between oligosaccharides and astringency.

Pilot-scale evaluation the enological traits of a novel, aromatic wine yeast strain obtained by adaptive evolution.

In the competitive context of the wine market, there is a growing interest for novel wine yeast strains that have an overall good fermentation capacity and that contribute favorably to the organoleptic quality of wine. Using an adaptive evolution strategy based on growth on gluconate as sole carbon source, we recently obtained wine yeasts with improved characteristics in laboratory-scale fermentations. The characteristics included enhanced fermentation rate, decreased formation of acetate and greater production of fermentative aroma. We report an evaluation of the potential value of the evolved strain ECA5™ for winemaking, by comparing its fermentation performance and metabolite production to those of the parental strain in pilot-scale fermentation trials, with various grape cultivars and winemaking conditions. We show that the evolved strain has outstanding attributes relative to the parental wine yeast strain, and in particular the production of less volatile acidity and greater production of desirable volatile esters, important for the fruity/flowery character of wines. This study highlights the potential of evolutionary engineering for the generation of strains with a broad range of novel properties, appropriate for rapid application in the wine industry.

Sensory representation of typicality of Cabernet franc wines related to phenolic composition: impact of ripening stage and maceration time.

Phenolics are responsible for important sensory properties of red wines, including colour, astringency, and possibly bitterness. From a technical viewpoint, the harvest date and the maceration duration are critical decisions for producing red wine with a distinctive style. But little is known about the evolution of phenolics and of their extractability during ripening to predict the composition of the wine and related sensory properties. The aim of this study was to understand the relationship between the sensory profile of the wines and (i) the ripening stage of the berries (harvest date) and (ii) the extraction time (maceration duration). Phenolic acids, flavonols, anthocyanins and proanthocyanidins of Vitis Vinifera var. Cabernet franc were measured in grapes and in wines from two stages of maturity and with two maceration durations. Phenolic composition was analysed by high performance liquid chromatography, after fractionation and thiolysis for proanthocyanidins. The distinctive style of wines was investigated by descriptive analysis (trained panel), Just About Right profiles and typicality assessment (wine expert panel). Relationships between phenolics and sensory attributes were established by multidimensional analysis, and phenolics were classified according to sensory data by ANOVA and PLS regressions. Astringency, bitterness, colour intensity and alcohol significantly increased with ripening and astringency and colour intensity increased with maceration time. Grape anthocyanins increased and thiolysis yield significantly decreased with ripening. In wine, proanthocyanidins increased, and mean degree of polymerisation and thiolysis yield decreased with longer extraction time. The high impact of harvest date on the sensory profiles could be due to changes in anthocyanin and sugar contents, but also to an evolution of proanthocyanidins. Moreover, proanthocyanidin composition was affected by maceration time as suggested by the decrease of thiolysis yield. Our results suggest that the wine sensory quality established by the expert panel, is linked as expected to grape quality at harvest, reflected by sugar and anthocyanin contents, but also by thiolysis yield, which requires elucidation.

Sensory characteristics changes of red Grenache wines submitted to different oxygen exposures pre and post bottling.

It is widely accepted that oxygen contributes to wine development by impacting its colour, aromatic bouquet, and mouth-feel properties. The wine industry can now also take advantage of engineered solutions to deliver known amounts of oxygen into bottles through the closures. This study was aimed at monitoring the influence of oxygen pick-up, before (micro-oxygenation, Mox) and after (nano-oxygenation) bottling, on wine sensory evolution. Red Grenache wines were prepared either by flash release (FR) or traditional soaking (Trad) and with or without Mox during elevage (FR+noMox, FR+Mox, Trad+noMox, Trad+Mox). The rate of nano oxygenation was controlled by combining consistent oxygen transfer rate (OTR) closures and different oxygen controlled storage conditions. Wine sensory characteristics were analyzed by sensory profile, at bottling (T0) and after 5 and 10 months of ageing, by a panel of trained judges. Effects of winemaking techniques and OTR were analyzed by multivariate analysis (principal component analysis and agglomerative hierarchical clustering) and analysis of variance. Results showed that, at bottling, Trad wines were perceived more animal and FR wines more bitter and astringent. Mox wines showed more orange shade. At 5 and 10 months, visual and olfactory differences were observed according to the OTR levels: modalities with higher oxygen ingress were darker and fruitier but also perceived significantly less animal than modalities with lower oxygen. Along the 10 months of ageing, the influence of OTR became more important as shown by increased significance levels of the observed differences. As the mouth-feel properties of the wines were mainly dictated by winemaking techniques, OTR had only little impact on "in mouth" attributes.

Sensory dimension of wine typicality related to a terroir by Quantitative Descriptive Analysis, Just About Right analysis and typicality assessment.

The distinctive French wine style "Anjou Village Brissac" was investigated through Quantitative Descriptive Analysis by a sensory expert panel, through Just About Right analysis by wine experts, and through assessment of the typicality by wine experts. Typicality was defined as perceived representativeness, with good examples of the concept being considered more typical. Wine experts were producers, winemakers, and enologists from the area. Three types of data were used: (i) quantitative descriptive data on a non-structured scale, (ii) preference data that corresponded to a global typicality index for the wine on a non-structured scale, (iii) data collected on a Just About Right non-structured scale, where the middle of the scale, for each attribute, corresponded to Just About Right, an ideal of typicality for wine experts. The two panels, sensorial experts and wine experts, rated 24 Cabernet franc wines from different French "Appellation d'Origine Contrôlée", including two-thirds "Anjou Village Brissac". Single factor analysis was performed on each panel's data, and results were compared. Multifactor analysis was performed with the data of both panels to highlight the correspondence between the panels. ANOVAs conducted on the differences to the ideal scores permitted the wines to be sorted according to the similarity of their profiles. A penalty analysis was performed to determine, for each attribute, if the rankings on the Just About Right scale were related to significantly different results in the preference scores. Therefore, multivariate analysis of Just About Right scales served (i) to show an ideal point, (ii) to point out the distance between each product, (iii) and to evaluate the consensus of producers. The results showed the relevance of the sensory expert panels in discriminating the products. The panel of wine experts proved relevant for characterizing the global quality of the wines but did not appear consensual for some attributes. Some attributes from the wine expert panel could be explained by precise descriptors generated by the sensory expert panel. Typicality ratings were considered in relation with descriptive ratings, for example astringency and color attributes. The results presented in this study suggest the usefulness of these sensory techniques for describing wine typicality related to a terroir.