Content of chemical constituents of 12 kinds of black tea

Abstract

Previous studies analyzing black tea constituents have been carried out primarily in regards to theaflavins, thearubigins, catechins, and caffeine. In this study, four major theaflavins, total amino acid, total polyphenols, caffeine, eight major catechins, gallic acid, theanine, glutamic acid, γ-aminobutyric acid, three major free sugars, oxalic acid, and water soluble substances were determined for 12 different kinds of black teas produced in several countries of the world. Also infusion color indicators and pH were measured. There was wide variation found in the content of constituents among the teas tested, and the content ranges of oxalic acid, gallic acid, three kinds of sugars and three kinds of amino acid were newly suggested. The content of total theaflavins showed negative regression with L values and a high positive regression with values for red color degree of infusion.