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 distinguish the light from the heavy pressings wines, but this could be explained by them having similar amounts of total phenolics based on their A280. Juice fining using a gelatine fining agent at a medium and high rate did not affect the phenolic taste of the wines compared with a heavy pressings control. However, the fining agents as applied under the conditions of this study also did not affect either A280 or A320 suggesting that they were ineffective in fining total phenolics or total hydroxycinnamic acids from these wines. Others have also shown that gelatine fining of white juices is ineffective in reducing total phenolics in white wine. Adding 100 mg/L of gelatine to commercially produced Paradella juices did not influence the total phenolics of the finished wine (Puig-Deu et al. 1996), nor did adding 300 mg/L of gelatine to V. rotundifolia juices (Sims et al. 1995). Gelatine fining at a high rate of 500 mg/L did not reduced either total phenolics, non-flavonoids or flavonoids in various V. vinifera juices (Cosme et al. 2008). However, they showed that most small MW flavanols were reduced particularly when gelatine with a low molecular weight distribution was used. In conclusion, the results of this trial indicate that differences in ‘phenolic taste’ amongst wines made using conventional white wine making practices can be distinguished, at least by highly experienced wine assessors. Page | 24
AWRI: Identification Of The Major Drivers Of ‘Phenolic’ Taste In White Wines 3 Do Different Phenolic Profiles Affect the Taste Profiles of White Wines? 3.1 Introduction It has been established in an Australian scenario that overall ‘phenolic taste’ amongst Australian wines can be distinguished, at least by highly experienced wine assessors (Chapter 2). However, the diversity of varieties and winemaking styles is known to result in wines with differing amounts and types of phenolics i.e. different ‘phenolic profiles’. It remains to be established whether, and in what ways, these different wine phenolic profiles might influence phenolic tastes. In order to study this, whole phenolic fractions of differing phenolic composition were first isolated from commercial wine and characterised by HPLC. The whole phenolic fractions were then added to two commercial wines after which their phenolic taste profiles were quantified by a trained sensory panel. Wines created from a diversity of varieties and winemaking styles inherently have a range of different basic composition. Alcohol concentration can vary greatly and can be highly influential in the perception of phenolic tastes (see Chapter 5) and as such, its influence was also investigated as a variable with these whole phenolic fractions. 3.2 Methods 3.2.1 Sample Preparation A current vintage commercial Riesling and unwooded Chardonnay were used as base wines. Whole phenolics were extracted from another three wines that were deemed by a panel of experienced tasters to exhibit phenolic tastes. They were a McLaren Vale Fiano, a Canberra District Viognier and an Alsatian Gewurztraminer. The whole phenolics from these wines were eluted off Amberlite FPX66 resin using 96% ethanol, the ethanol evaporated under vacuum and redissolved in water and freeze dried. All samples of whole phenolics were kept at -80°C before use. Whole phenolics were extracted from a volume of wine as described above and then 50% of the whole phenolics that were collected were added back to the same volume of base wine just prior to tasting. An additional treatment factor of an additional 1% ethanol v/v (96%, Tarac Industries, SA) was included to assess the effect of alcohol concentration on the perception of phenolic tastes. The whole phenolic fractions were analysed using the HPLC method described in Section A.3. Page | 25
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Identification of the major drivers of 'phenolic' taste in ... - GWRDC

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