Overview
The report is a detailed review of 'phenolic' taste, an important aspect of white wine sensory properties and preference, and analyses how to manage it. Contrary to common assumption, astringency was driven mainly by low pH rather than phenolics, viscosity increased with pH, and alcohol hotness was suppressed by phenolics including caftaric acid. Grape Reaction Product increased oiliness, while bitterness was linked to other, unidentified phenolics. Skin contact raised phenolics and pH, so the report recommended considering pH effects when choosing treatments. Phenolics helped define style and winemaker quality scores, but consumer liking depended more on residual sugar and alcohol. The report includes detailed information on South Australian Chardonnay, Riesling, Viognier and Fiano wines, and a new HPLC method separating over 80 phenolics.
The term ‘phenolic taste’ is ill-defined, but is proposed to include the taste and textural attributes of astringency, bitterness, viscosity, oiliness, metallic and pungency/burning. The molecules responsible for causing ‘phenolic taste’ also remain unknown and, indeed, debate continues as to whether these molecules are even phenolic. While some tastes and textures in white wine such as ‘hotness’ can be confidently attributed to major features of the wine matrix such as alcohol (Gawel et al. 2008), others such as bitterness and astringency have been associated with the presence of phenolic compounds. The cause of other mouth-feel characters such as viscosity, oiliness, metallic or pungency/burning is unclear, but these attributes are often found in wines that were made using processes that encourage phenolic pick-up during winemaking.
This project investigates the role of phenolics on white wine character and style. Specifically its objectives were to identify the molecular basis of ‘phenolic’ taste by broadly considering all potential compounds, phenolic and non-phenolic, that may be involved in the different tastes and textures believed to be associated with phenolics in white wine, and use winemaking practice to create different phenolic styles. The role that pH and alcohol play on the perception of phenolic taste and texture was also explored. This work will allow winemakers to make better informed decisions about how to manage ‘phenolic’ taste in their white wines to achieve their desired wine style.
Abstract
The effects of the phenolic composition, alcohol and acidity levels of white wines on their mouth-feel and taste (astringency, bitterness, viscosity, oiliness, and hotness/pungency) were assessed. Phenolic composition impacts on these attributes, but the size of the effect depends on wine alcohol and pH.
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