Relationship between Sencha Evaluation in the Competition and its Components Including Amino Acids, Catechins, Theogallin, Gallic Acid, and Caffeine

Abstract

A total of 119 sencha products, which is a kind of green tea, were classified into three grades namely: High, Medium, and Low, at a tea quality competition done at Kansai area in 2015. We collected 10 samples from each grade (High, Medium, Low) based on the ranking of the examination results. The tea leaves were used for extraction and determination of amino acids, catechins, theogallin, gallic acid, and caffeine. The contents of theanine, glutamic acid and arginine were significantly higher in High grades than the other grades. The contents of epicatechin gallate was significantly higher in High grades, and epigallocatechin gallate tended to increase from lower grade to higher grade. In addition, the theogallin content was significantly higher in High and Medium grades than those in Low grade. These compounds were also considered to be important compounds for the quality of tea by the principal component analysis.