Interaction between Polyphenols of Tea and Amino Acids during Heating

Abstract

In order to clarify the interaction between polyphenols and amino acids during manufacturing of green tea, the chemical changes during heating of the mixtures of crude catechin extracted from green tea or (+)-catechin and amino acids were investigated. The mixtures of crude catechin extracted from green tea, glutamic acid, serine, theanine and arginine were freeze-dried and heated at 150°C for 30-100min, The heated mixtures were dissolved in boiling deionized water, and visible absorption spectrum of the solutions and the loss of each compounds were measured. Furthermore, the same experiments were made using (+)-catechin and several amino acids or related compounds. The results indicated that at heating of the mixture of crude catechin and four amino acids, the degree of the color of the solution and the loss of four catechins and theanine were greater than at heating of the crude catechin or the mixtures of four amino acids separately. Furthermore, at heating of the mixtures of (+)-catechin and several amino acids or related compounds, the loss of (+)-catechin were greater than at heating of (+)-catechin only, but the influence of acidic amino acids as less than that of the other amino acids.