Identification of the major drivers of 'phenolic' taste in ... - GWRDC

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AWRI: Identification Of The Major Drivers Of ‘Phenolic’ Taste In White Wines Correlation coefficient (r) 92 1.0 0.8 0.6 0.4 0.2 0.0 -0.2 -0.4 -0.6 -0.8 -1.0 Figure 8-22: Correlation coefficients between concentration of phenolic compound classes and sensory attributes. All 2010 wines. * indicates sensory attribute was adjusted for pH effect Good associations were seen between bitter and bitter aftertaste character and A280 in 2010 (Table 8-5). The concentrations of many of the phenolic groups were associated with bitter aftertaste (Figure 8-22). PLS regression analysis showed that a significant contributor to the relationship were the flavan-3-ols, benzoic acids and to a lesser extent GRP and the cinnamic acids. Flavan-3-ols were found to be abundant in one of the few bitter fractions extracted from commercial wines (Chapter 6), and have been reported to be important bitter compounds in tea (Narukawa et al. 2010). Adding GRP and caftaric acid to model wine did not result in a consistent increase in bitterness (Chapter 7). PLS analysis suggested that GRP and caftaric acid have some influence on bitterness. However, it is reasonable to assume that the direct approach of assessing these compounds in isolation will be more robust than using correlative methods such as PLS. Astringency* Viscosity* Hotness Acidity Bitter AT Acid AT Benzoic acids Benzoic acid glycosides Benzoic acid ethyl esters GRP's Cinnamic acids Cinnamic acid glycosides Cinnamic acid ethyl esters Phenols Total peak area measured at 280 nm has been used as a proxy for total phenolics and was correlated against sensory ratings given to the 2010 wines (Figure 8-24). Astringency (adjusted for pH effect), hotness and acidity were negatively correlated with peak area, while viscosity (adjusted for pH effect) and bitter aftertastes were positively correlated with peak area.
AWRI: Identification Of The Major Drivers Of ‘Phenolic’ Taste In White Wines PLS Coefficient 93 2.0 1.5 1.0 0.5 0.0 -0.5 -1.0 -1.5 -2.0 Astringency* (0.034) Viscosity* (0.001) Hotness (0.200) Figure 8-23: PLS regression coefficients for sensory attributes modelled on concentration of phenolic classes. All 2010 wines. * indicates sensory attribute was adjusted for pH effect. These correlations were in close agreement with the correlations with spectrometric measures at 280 nm. The relationships between phenolic composition and phenolic tastes have only been examined in a single vintage, so the results should be considered as indicative. Correlation Coefficient (r) Acidity (0.009) Bitter AT (0.004) Benzoic acids Benzoic acid glycosides Benzoic acid ethyl esters GRP's Cinnamic acids Cinnamic acid glycosides Cinnamic acid ethyl esters Phenols Phenol glycosides Flavan-3-ols Flavanones flavanonol glycosides flavonols flavonol glycosides flavonol ethyl esters 1.0 0.8 0.6 0.4 0.2 0.0 -0.2 -0.4 -0.6 -0.8 -1.0 Astringency* Viscosity* Hotness Acidity Bitter AT Acid AT Acid AT (0.044) Figure 8-24: Correlation coefficients (r) for sensory attributes and total phenolics measured by HPLC peak area. * indicates sensory attribute was adjusted for pH effect.
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