Use of an experimental design approach for evaluation of key wine components on mouth-feel perception

To simultaneously explore the primary and interactive effects of proanthocyanidin (‘tannin’), ethanol, anthocyanin and wine polysaccharide concentrations on the mouth-feel perception of wine like media, a sensory study based on an incomplete factorial design was conducted. Two grape polyphenol fractions, i.e. grape seed tannins and anthocyanins, and two fractions of wine polysaccharides, (mannoproteins+arabinogalactan-proteins and rhamnogalacturonan II) were prepared and analysed. A panel of 15 trained judges generated a series of mouth-feel descriptors and rated their intensities while samples containing various levels and combinations of the components were held in mouth and after expectoration. The sensory perception was primarily determined by tannin concentration. However, the attribute ratings were also strongly influenced by all other factors both directly and through interactions. The intensities of all astringency descriptors increased with tannin concentration and were reduced when rhamnogalacturonan II was added. Bitterness increased with ethanol level and decreased in the presence of proteoglycans. Secondary effects observed included both masking and enhancement of the primary effects but also specific interaction effects. The latter are probably related to differences in the structural organization and properties of molecular assemblies involving polyphenols, polysaccharides, and ethanol.