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

AWRI: Identification Of The Major Drivers Of ‘Phenolic’ Taste In White Wines
6.2.5 Analysis of Fractions
The fractions were analysed using the HPLC method described in section A.3. Peak areas were used to
evaluate the relative contribution of different phenolic species to the fraction. A280, A320 and A370 of the
sensory samples were taken at the conclusion of each session.
6.2.6 Statistical Analysis
A two way analysis of variance with assessors and fraction addition as factors was conducted by wine
from which the fractions were extracted. Judges were treated as random factors. While the fractions were
collected in the same way from each wine, HPLC analysis clearly indicated that they varied in at least one
component. Therefore it was necessary to analyse each set of fractions collected from each of the three
wines separately. A Dunnett’s test was conducted to compare the sensory effects of each fraction addition
on that of the control wine. A Partial Least Squares analysis was also conducted with the sensory
attributes as dependent variables and A280, A320 and A370 as dependent variables.
6.3 Results and Discussion
6.3.1 Fraction Composition
The Oasis HLB resin has both hydrophilic and hydrophobic groups and as such it works in a mixed mode.
As a result, few fractions contained phenolic compounds that were confined to a particular phenolic class.
However, there were distinct compositional patterns; Figure 6-1 depicts the HPLC traces of each fraction
while Table 6-1 gives the relative contributions of compounds classed by their A280, A320 and A370.
Flow Through (FT) fractions were complex, but primarily consisted of the esterified hydroxycinnamic
acids and grape reaction products. But even these differed. Notably, the fraction taken from the
Gewurztraminer was distinguished by a cysteine GRP derivative not found in the other FT fractions.
F1 fractions contained tyrosol and mostly free hydroxycinnamic acids, and in the case of the two
Australian wines, a syringic acid like compound. The F1 fractions taken from the two Australian wines
also contained quercetin-3-glucuronide.
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