Factors affecting bitterness, astringency and mouthfeel in wine

Astringency and sweetness were rated using time-intensity methods(T-I) in red wine containing two levels of phenolics, and five levels of sucrose. Maximum intensity and total duration for astringency decreased significantly with increasing sucrose concentrations. In contrast, sweetness was not affected by varying astringency levels. No differences in perception of astringency or sweetness were found as a function of PROP (6-n-propylthiouracil) taster status, although there was significant difference in intensity and persistence of astringency as a function of salivary flow. Consistent with our previous work, judges with low salivary flow rates rated astringency higher than high-flow subjects, but no difference for sweetness was found. Five attributes were rated by T-I in six hydroxy benzoic acid derivatives, differing only in number and position of hydroxy groups. Maximum intensity varied significantly for astringency, bitterness, prickling, sourness and sweetness. Gentisic acid was the most sour and bitter, salicylic and gentisic acids were highest in astringency, and m-hydroxybenzoic acid was sweetest. Benzoic acid had the highest prickling feeling which lasted 20 sec longer than salicylic acid and 40 sec longer than the other samples which elicited lowest prickling sensation. To understand factors influencing temporal perception, sweetness of solutions of 20, 80 or 140 g/L glucose was rated by T-I. Saliva expectorated by these same judges initially at 7 sec and at 30 sec intervals up to two min was analyzed for glucose concentration. Saliva glucose concentration was higher in the low flow judges at 4 of the 6 intervals. For each subject, the decrease in sweetness intensity was correlated with the oral glucose concentration. However, there was no significant difference in sweetness perception between the saliva flow-groups. Sweetness and viscosity were rated by T-I in solutions of glucose which were thickened with a tasteless gum. In contrast to the strong salivary response to acid or tannin found previously, which increases viscosity from that of water (1 cp) to the high gum level (50 cp) failed to increasing the salivary flow over that observed in response to water. Small significant differences in salivary flow were observed when 9 and 14%(w/v) glucose were tasted. No perceptual interaction occurred between viscosity and sweetness. Unlike previous work in which sweetness was increased by physical viscosity, no difference in sweetness was found when the viscosity was raised by 50 cp. Correspondingly, no increase in viscosity were perceived when sugar level was raised.