Techniques for universal evaluation of astringency of green tea infusion by the use of a taste sensor system

A practical method for universal evaluation of the astringency of green tea infusion by a taste sensor system was established. The use of EGCg aqueous solution as a standard enabled analysis with high accuracy and reproducibility. The sensor output was converted into taste-intensity on the basis of Weber's and Weber-Fechner laws, which was named the "EITast" value ("EIT" and "ast" are abbreviations for "Estimated Intensity of Taste" and "astringency" respectively). It was clarified that green tea infusion is to be classified into eight grades on the EITast scale. Furthermore, the high correlation of the EITast value with the human gustatory sense and the high stability of the taste sensor were proved.