The results showed that the content of some free α-amino acid contents included phenylalnine, methionine, leucine, valine and isoleucine in tea leaves were significantly increased during withering but vice versa during fermentation stage. | Journal of Science and Technology 55 (1) (2017) 1-7 DOI: CHANGES IN COMPOSITION OF FLAVOUR PRECURSOR AMINO ACID IN LEAVES OF TEA (Camellia sinensis) DURING ORTHODOX BLACK TEA PROCESSING Hoang Quoc Tuan*, Nguyen Duy Thinh, Nguyen Thi Minh Tu Hanoi University of Science and Technology, School of Biotechnology and Food Technology, Department of Quality Management, 1 Dai Co Viet Road, Hanoi, Vietnam * Email: ; tuanhqibft@ Received: 10 May 2016; Accepted for publication: 25 November 2016 ABSTRACT The content of amino acids in tea leaves of cultivars Phu Ho 11 at different stages of OTD black tea manufacture included withering, fermentation and drying was measured. Considerable changes of amino acids were observed during entire processing, among them total free amino acids were increased both in withering and fermentation stages and decreased at drying stages. The results showed that the content of some free α-amino acid contents included phenylalnine, methionine, leucine, valine and isoleucine in tea leaves were significantly increased during withering but vice versa during fermentation stage. While other amino acids such as alanine and glycine were found to be increased in both stages of processing. The zero-order, first-order and quadratic models were used to explain the α-amino acid included alanine, valine, isoleucine, leucine and phenylalanine changes kinetics during processing and it was observed that 4 models including linear, growth, compounds and quadratic could be used for explanation of the changes of flavour compounds during OTD black tea processing. Keywords: black tea, amino acid, prediction model. 1. INTRODUCTION Tea is one of the most popular and widely consumed beverages in the world because of its refreshing taste, attractive aroma, and potential healthy benefits. It is made from the leaves of the plant Camellia sinensis (L.). Generally, tea can be broadly classified according to the .
