Analysis of quality-related nonvolatile metabolites in tea (Camellia sinensis) resources with different shoot colors

The shoot color of tea resources are various, such as green, purple and yellow, however, the differences in their main nonvolatile metabolites and quality of tea had not been clarified. In this study, 21 nonvolatile metabolites of 15 tea resources with three different shoot colors were analyzed. Our results showed that the coefficient of variation of 21 nonvolatile metabolites of tea resources was yellow shoots (23.83%) green shoots (20.95%) > purple shoots (20.18%). The contents of water extract, tea polyphenols, total catechins, anthocyanins and flavonoids in purple shoots were significantly higher than those in green and yellow shoots; the contents of free amino acids in yellow shoots were significantly higher than those in purple and green shoots, the contents of chlorophyll and carotenoids in yellow shoots were significantly lower than purple and green shoots (P<0.05); the contents of most metabolites in green shoots were between purple and green shoots. Yellow shoots and green shoots were suitable for producing high quality green tea, while purple shoots were poor. PLS-VIP analysis showed that there were differences in quality-related key nonvolatile metabolites among three kinds of tea resources. Finally, seven different metabolites including free amino acids, anthocyanins, chlorophyll a, chlorophyll b, carotenoids, non-ester catechins and flavonoids were used to establish an effective classification method for three kinds of shoot color tea resources. The results provided a basis for us to understand the quality-related nonvolatile metabolites of tea resources with different bud and leaf colors.