Aftertaste evaluation of sake using a taste sensor

Aftertaste is important for human sensation and provides rich and sophisticated flavor. In general, foodstuffs with sufficient aftertaste are considered to be of high quality and impart a pleasant taste to most people. A taste sensing system (taste sensor), that is, the electronic tongue, is effective for the evaluation of aftertaste of a variety of foods and drinks. However, for sake, sample differences in aftertaste data (CPA value) are so small that we cannot evaluate them adequately. The optimization of the measurement procedure for the sensor BT0, which is mainly used for the evaluation of the bitterness of hydrochloride medicines, enabled the evaluation of the aftertaste of sake in this study.Experiments on the concentration dependence of major tastants contained in sake revealed that the tastants detected by the sensor BT0 are peptides with some hydrophobic portion and also that hydrophilic substances such as ethanol, glucose, amino acids, and organic acids do not affect the CPA data of the sensor BT0. This indicates that the aftertaste of sake derived from peptides can be evaluated by using the sensor BT0. Data from commercial sake obtained using the sensor BT0 indicated that junmai sakes usually have larger values, which corresponds to the fact that junmai sakes usually have a strong and lasting flavor probably because of the peptides. In addition, for the sensor BT0, a good correlation was observed for aftertaste data with a sensory test. On the other hand, it was confirmed by data from commercial sake that kimoto sakes usually have larger values of the sensor CT0, which, while responding to organic acids in some cases, is originally a saltiness sensor for foodstuffs. This seems in line with the fact that kimoto sakes usually contain more organic acids and taste somewhat strong and full-bodied.From the above results and considerations, it was suggested that, by using the two sensors, the taste of sake can be evaluated in a comprehensible manner. A way of presenting the differences in the taste of sake to consumers was also proposed.