Enzymatic quality enhancement of oolong tea based on grade difference analysis

Abstract

The quality of oolong tea in summer and autumn is generally lower than in spring, resulting in a loss of economic benefits. We found that this was due to the higher tea polyphenol content and lower sugar and amino acid content of summer and autumn oolong teas. Here, we used cellulase, protease and tannase for targeted enzymatic hydrolysis of low-quality teas to reduce the tea polyphenol content while increasing the soluble sugar and amino acid contents. By optimizing the ratio, concentration and treatment temperature of the added enzymes, the soluble sugar and amino acid contents of low- and middle- quality tea were increased by 6%-128% and 12%-88%, respectively. The ester catechin content was reduced by 12% and the total catechin content was reduced by 41%. The aroma of middle- and low-quality tea was transformed into the characteristics of high-quality tea. Therefore, directed enzymatic degradation is a promising technology for tea quality improvement.