Evaluation of Astringency and Umami of Green Tea Infusions with Different Elution Conditions Using a Taste Sensor System

A taste sensor system has been used to grade the astringency and umami of green tea infused with hot water. The objectives of this study were to evaluate the capability of the taste sensor system for evaluating the taste of green teas infused with water of various temperatures, including ice brewing, and brewing durations. Sensory evaluation indicated that the concentration of gallate-type catechins was a better indicator than the total catechin concentration for evaluating the astringency of green tea infusions. The estimated intensity of astringency by the taste sensor system showed a high positive correlation with gallate-type catechin concentrations in green tea infusions prepared with different water temperatures or infusion durations. Also, the estimated umami intensity in the same green tea infusion samples by the taste sensor system showed a high positive correlation with the total amino acid concentration. Amino acids are the main contributors to umami. Regarding mainly high-grade teas, we propose that a taste sensor system is suitable for determining the best combination of time and temperature for brewing green tea and for evaluating the quality of green tea brewed with low-temperature water. (Received Jul. 23, 2013 ; Accepted Feb. 17, 2014)