Astringency intensity increases upon successive sips of the same wine or astringent stimuli OR of wines tasted at a session. To determine which rinse best reduces this carryover effect, astringency of red wine was rated continuously while wine was sipped, spit (at 10s) and rinses (or crackers) were sipped (or chewed) at 20s and spit at 30s. Overall, pectin was the most effective rinse for reducing astringency between samples and minimizing this carry-over phenomena. Pectin reduced astringency intensity from 30 s after the wine was sipped (which was 10 s after the rinse was expectorated) more than CMC, Polycose or water. Although a high concentration of pectin was the MSOT effective rinse, it was not signficantly better than a low concentration of pectin or a high concentration of CMC. In another test, Pectin reduced astringency after 30s more than unsalted crackers or water. Although water lowered astringency from 30 to 40s more than crackers, after 40s crackers were more effective. For routine tests in a winery or at competitions, rinsing with a pectin solution (4 to 5 g/L) between wines should greatly increase the reliability of the tasting.
The influence of sweetness and of flavor (vegy or fruity) on perception of astringency was examined in red wine. Astringency intensity was significantly lower in the sweetened wine, than the base wine or flavored wines. Since aspartame was used, and no increase in viscosity occurred upon sweetening, the suppression of astringency is solely due to cognitive interaction. When fruitiness was rated in sweetened and flavored wines, a similar cognitive enhancement was observed in that the sweetened (unflavored) wine was rated fruitier than a fruity-flavored wine or the base wine.
Consistent with previous studies, astringency was rated less intense when artificial saliva containing salts was introduced at a medium flow rate (5 ml/min) than at a low flow rate (o.5 ml/min). When wine was sipped repeatedly, the maximum intensity (IMAX) of astringency increased with each sip at low and medium flow rates of introduction of the artificial saliva, although it decreased upon successive sips at high flow rates (8 ml/min). When 3g/L gelatin was added to the artificial saliva the same effect was observed. However, there was no difference in astringency IMAX between artificial saliva with and without protein at either flow rate for any sip, which indicates that further research is needed to understand perception of astringency.