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AWRI: Identification Of The Major Drivers Of ‘Phenolic’ Taste In White Wines 4 The Role of Phenolics in White Wine Style: Winemaker Perception of Quality, and Consumer Acceptance of Commercial White Wines 4.1 Introduction As described in Chapter 3, the whole phenolics isolated from the three stylistically different wines (Fiano, Gewurtztraminer, Viognier) contributed to phenolic taste profiles when reconstituted in base wines. Thus, for the first time we demonstrated that different wines with different phenolic composition can display different textures when tasted in the same matrix (alcohol, pH, TA etc). This suggested that phenolic composition differences are a determinant of textural differences in white wines. However, of course, in ‘real’ wines these diverse phenolic profiles occur in the presence of a diverse range of matrices in terms of, for e.g., flavour, pH, acidity, alcohol, sugar etc. While it is widely accepted that specific combinations of flavour profiles, acidity and alcohol define specific styles, the role of phenolics is less well understood. So here we investigate the role of phenolics in contributing to various commercially acceptable styles produced from two important Australian white varieties. Furthermore, we explore how phenolics and other compositional factors influence winemaker perception of Riesling quality, and general Australian consumer acceptance of white wine. 4.2 Background 4.2.1 Study 1: Effect on ‘Pinot G’ Style The variety known as Pinot Gris in Alsace, Pinot Grigio in North East Italy, Grauburgunder in the Baden region of Germany and increasingly in Australia as ‘Pinot G’ presents a useful case study for investigating the role of phenolics in white wine style. The Italian approach to the variety is to harvest it before it undergoes its characteristic loss of acidity at later ripening stages. This practice results in wines that are characterised by subtle varietal characters, light body and crisp acidity. The Alsatian and German approaches of using riper grapes, vinifying juices containing solids, often following pre-fermentation skin contact, results in more aromatic styles that are characterised by higher alcohol levels, richer flavours and fuller texture. While the higher alcohol style may be expected to be fuller when compared with their leaner Italian counterparts, it is unknown whether higher phenolics that might arise following later Page | 30
AWRI: Identification Of The Major Drivers Of ‘Phenolic’ Taste In White Wines harvesting and greater maceration are associated with any specific sensory attributes, or with general conformance to a particular style. 4.2.2 Study 2: Effect on Riesling Style and Perceived Quality Riesling is the fourth most important Australian white grape variety in 2010 in terms of production (ABS Cat. 1329.0). Dry Riesling styles vary substantially - from the light bodied, low alcohol, high acid styles typical of the Ruhr/Rhine region of Germany through to fuller bodied, higher alcohol styles typical of the Alsatian region of France. Australian producers have generally produced leaner, aromatic wines with higher acidity in the Germanic style. In order to preserve the varietal character, Australian winemakers have generally avoided winemaking strategies that could potentially contribute to the phenolic content of the finished wine (McLean, 2005). 4.2.3 Study 3: Effect on Perceived Quality and Consumer Acceptance of Commercial Dry White Wines The importance of phenolic content in dry white wines compared with other aspects of their composition such as alcohol, acidity and residual sugar is unknown. Here we investigate the role of phenolic content on winemaker perceived quality and consumer acceptability of commercial dry white wines. 4.3 Methods 4.3.1 Study 1: Effect on ‘Pinot G’ Style Wine samples 22 commercial Pinot Gris/Pinot Grigio wines that made up the training set for the AWRI’s Pinot Gris style project were used - 18 were Australian, three were from Alsace, France and one was from New Zealand. They formed a diverse set of styles representing that variety, ranging from a fuller bodied, higher alcohol style typically labeled in the marketplace as ‘Gris’, to the lighter bodied, lower alcohol, high acid style typically labeled as ‘Grigio’. The ‘Grigio’ style that typifies Italian examples of the varietal, contrasts with the ‘Gris’ style that is typified by wines of Alsatian origin. The tasters and sensory methods The panel consisted of ten experienced tasters who were members of an AWRI tasting panel. They all had between 5 and 25 years continuous tasting experience as part of their profession and had undertaken the AWRI’s Advanced Wine Assessment Course. Around half the tasters also had winemaking qualifications and/or had some practical winemaking experience. Page | 31
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