Reducing Bitterness In Wines. The effect of wine composition, sample evaluation method and salivary flow on sourness, bitterness and astringency
The effect of method of sample evaluation on sourness, bitterness and astringency was explored in water and in wine. The temporal responses using “sip and spit” procedure (the normal lab protocol) were compared to the TI responses when samples were sipped and swallowed, more similar to actual consumption method. With the exception of astringency in wine, no differences between the two methods were found. When samples were swallowed, astringency intensity was slightly lower and the total duration of astringency was slightly shorter, than when the samples were expectorated. However, considerable variation among judges occurred in this very small number of judges, thus this effect is not be concluded to significantly affect perception based on this preliminary study. To explore the effect of rate of salivary flow on TI perception of these three attributes, sourness, bitterness, and astringency were evaluated using expectoration. No significant differences were seen among flow groups, in contrast to a previous study in which high flow judges tended to have a shorter persistence of bitterness or astringency than low flow judges. To determine if any real effects of salivary flow occur, a larger number of subjects needs to be examined and a method for standardizing their sensory ratings over times must be found. Bitterness and astringency of epicatechin and catechin, the monomeric isomers (flavan-3-ols) of the phenols found in wine, were evaluated by both scalar and temporal methods (TI). By both, epicatechin was shown to be more intensely bitter than catechin, and by TI, bitterness lasted longer for epicatechin than catechin. While no difference in astringency was found by scalar tests, by TI, at higher concentrations, epicatechin had higher maximum astringency and longer duration of astringency than catechin. Both compounds were more bitter in 5%ethanol than in water, although the astringency did not vary significantly. The implications of these results for predicting wine flavor are unknown. On-going research in our lab is addressing differences in the tastes and intensities of different polymers of these two compounds in wine.