Identification of the major drivers of 'phenolic' taste in ... - GWRDC
Identification of the major drivers of 'phenolic' taste in ... - GWRDC
Identification of the major drivers of 'phenolic' taste in ... - GWRDC
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AWRI: <strong>Identification</strong> Of The Major Drivers Of ‘Phenolic’ Taste In White W<strong>in</strong>es<br />
8.3 Analytical Methods<br />
8.3.1 UV Spectra and Somers Measures (2010 and 2011 w<strong>in</strong>es)<br />
Analyses <strong>of</strong> <strong>the</strong> f<strong>in</strong>ished w<strong>in</strong>es were carried out follow<strong>in</strong>g bottl<strong>in</strong>g. The UV spectra were recorded <strong>in</strong> 2<br />
mm matched quartz cuvettes us<strong>in</strong>g a Varian Cary 300 UV-Vis spectrometer. Total phenolics, total<br />
hydroxyc<strong>in</strong>namates and flavonoid extractibles were calculated as per Somers and Ziemelis (1985)<br />
(Appendix A.1).<br />
8.3.2 Phenolic Composition by HPLC (2010 w<strong>in</strong>es only)<br />
A detailed analysis <strong>of</strong> <strong>the</strong> phenolic composition <strong>of</strong> <strong>the</strong> 2010 w<strong>in</strong>es was determ<strong>in</strong>ed us<strong>in</strong>g HPLC-DAD<br />
analysis follow<strong>in</strong>g evaporation <strong>of</strong> <strong>the</strong> alcohol and a four-fold concentration under reduced vacuum<br />
(Section A.3). Peak identification was carried out by comparison <strong>of</strong> UV spectra derived from a sample<br />
that had been analysed by HPLC-MS/MS. Peak area was extracted from <strong>the</strong> chromatograms and<br />
expressed <strong>in</strong> equivalent mg/L <strong>of</strong> a related parent phenolic compound. All hydroxyphenolics/benzoic<br />
acids/flavanol were expressed <strong>in</strong> gallic acid equivalents (GAE), all hydroxyc<strong>in</strong>namates and grape reaction<br />
products (GRP) derivates as ferulic acid equivalents (FAE) and flavonols as quercet<strong>in</strong>-3-glucoside<br />
equivalents (Q3GE).<br />
8.4 Sensory Methods<br />
8.4.1 W<strong>in</strong>es from 2010 v<strong>in</strong>tage<br />
Tasters<br />
Thirteen <strong>taste</strong>rs (five males and eight females) were tra<strong>in</strong>ed for this study. All were experienced <strong>in</strong> <strong>the</strong><br />
descriptive analysis <strong>of</strong> aroma and flavour, and <strong>the</strong> palate sensations <strong>of</strong> bitterness, astr<strong>in</strong>gency and acidity.<br />
Ten <strong>of</strong> <strong>the</strong> <strong>taste</strong>rs had previously been <strong>in</strong>volved <strong>in</strong> <strong>taste</strong> and texture pr<strong>of</strong>il<strong>in</strong>g <strong>of</strong> phenolic fractions taken<br />
from commercial white w<strong>in</strong>es.<br />
Taster Tra<strong>in</strong><strong>in</strong>g<br />
Tra<strong>in</strong><strong>in</strong>g was conducted over six sessions. The first three sessions <strong>in</strong>volved attribute generation, attribute<br />
def<strong>in</strong>ition and ref<strong>in</strong>ement, with <strong>the</strong> latter also <strong>in</strong>volv<strong>in</strong>g identify<strong>in</strong>g attribute redundancies. Dur<strong>in</strong>g <strong>the</strong>se<br />
sessions, two w<strong>in</strong>es made from whole bunch pressed and free run juices (low phenolics) were <strong>taste</strong>d and<br />
compared with two w<strong>in</strong>es made from ei<strong>the</strong>r hard press<strong>in</strong>g juices or those that had undergone extensive<br />
sk<strong>in</strong> contact before fermentation (high phenolics). Standards for astr<strong>in</strong>gency, viscosity and bitterness<br />
(Appendix B, Table B-4) were also presented. A commercial white w<strong>in</strong>e made with extensive pre- and<br />
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