Chemical composition and discrimination with volatile profiles of Yongchuan Xiuya green tea with different baking treatments

Abstract

This study aimed to explore the effects of different baking treatments on the quality of Yongchuan Xiuya (YCXY) green tea. It was found that a long time baking at low temperature was beneficial to keep green colour, faint scent, mellow and fresh taste quality, whereas baking under high temperature was adverse to the quality. Baking treatments slightly regulated (−)-epigallocatechin, (−)-epicatechin, (−)-gallocatechin gallate, total chlorophyll and carotenoid. As the baking temperature rose, the content of tea polyphenols, gallic acid, catechins, caffeine, soluble sugar and polyphenols/amino acids ratio obviously decreased. A total of 40 kinds of volatiles were detected in these six tea samples. A model for aroma type discrimination was successfully established based on partial least squares-discriminant analysis (PLS-DA). Ten kinds of volatile substances were the key characteristic markers for the faint scent, chestnut aroma and high-fired aroma types of YCXY green tea. 1-hexanol, hotrienol and dimethyl sulfide were furtherly used to discriminant aroma type based on Fisher discriminant analysis (FDA).