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

AWRI: Identification Of The Major Drivers Of ‘Phenolic’ Taste In White Wines
5 The Effect of pH and Alcohol on the
‘Phenolic Taste’ in White Wine
5.1 Introduction
A solid body of work has established that pH and alcohol level greatly influence the perception of
astringency and bitterness of phenolic compounds found in red wines (see General introduction for a
review). Although white wine is relatively low in phenolics compared to red wine, the range in alcohol
and pH levels of white wines is greater.
Work from this project (Chapter 3) established that alcohol concentration positively enhanced four major
taste/textural attributes (astringency, viscosity, bitterness and hotness) in white wine, and that phenolics
and alcohol contributed in an additive way to these attributes. Interestingly, research into stylistically
different whole wines demonstrated that the astringency of Pinot Gris/Grigio wines was mostly associated
with low pH.
In order to further explore the influence and interactions of phenolics with the key matrix elements of
alcohol and pH on taste/textural attributes, an experiment was designed using a whole phenolics fraction
isolated from Riesling. Two alcohol concentrations (11.4% and 12.6% v/v) and two pH levels (3.0 and
3.3) were used.
5.2 Methods
5.2.1 Tasting Panel
A panel of 13 volunteer assessors comprising four female and nine male employees of the Australian
Wine Research Institute was convened. All had at least two years general wine tasting experience as part
of their profession, but none had previously participated in tastings specifically related to white wine
texture. All the panelists were experienced in using unstructured line scales to assess sensory intensities.
5.2.2 Taster Training
Training consisted of two, forty-minute sessions. In the first session, tasters assessed and discussed the
texture of six white wines that had previously been deemed by an experienced wine tasting panel to vary
in texture. The wines selected were made from both low phenolic (an Australian Riesling and unwooded
Chardonnay) and high phenolic styles (an Australian Fiano, Alsatian Gewurztraminer and Italian
Page | 39