The influences of different winemaking techniques on the mouthfeel of Shiraz Grapes

Abstract

The objective of this study was to determine the effect of ripeness and of different tannin extractionmethods on the sensory properties of wine, with a specific focus on mouthfeel properties. Quantitativedescriptive analysis (QDA) was performed to evaluate the sensory properties of 20 young Shiraz wines intwo phases. In Phase 1, wines from a cool area were evaluated and, in Phase 2, wines from a warm areawere evaluated. Clear differences were found between the wines from the two regions. Wines from thecooler region were generally associated with higher levels of total non-flavonoids and total anthocyanins,and more intense numbing and puckering sensations. In contrast, the wines from the warmer region asa group were associated with a more drying and grippy mouthfeel, as well as less total anthocyanins andtotal non-flavonoids. In the set of wines from the cooler region, the effect of ripeness was more pronouncedthan in the set of wines from the warmer region. In both cases, riper grapes resulted in a coarser surfacesmoothness, a more numbing sensation, a bitter aftertaste and less adhesive mouthfeel. The wines fromthe cooler region that were harvested at a riper stage were associated with many of the anthocyanins/anthocyanin derivatives and were negatively associated with hydroxycinnamate, procyanidin B1 anddelphinidin-3-glucoside-p-coumaric acid. In the warmer area, the riper grapes were again associated withanthocyanins/anthocyanin derivatives, but this time were strongly associated with procyanidin B2, caffeicacid, p-coumaric acid, catechin, coutaric acid and total non-flavonoids. The effect of tannin extractionmethod on the sensory properties of the wines from the warmer region was more pronounced than in thewines from the cooler region. Unfortunately, the differentiation between treatments was not consistent fromone ripeness level to the next. However, it appeared that the cold soak treatment differed the least from thecontrol, regardless of region or ripeness, whereas the post-maceration treatment differed the most basedon mouthfeel and phenolic composition. Although some mouthfeel attributes and phenolic compoundswere consistently associated with region and ripeness, it is not clear if mouthfeel can be manipulatedconsistently by tannin extraction methods.