Metabolic Profiling of Non-volatile Compounds during Xinyang Maojian Tea Processing Using Untargeted Metabolomics

Abstract

In order to understand the dynamic changes of non-volatile metabolites in Xinyang Maojian tea during processing, Xinyang Maojian tea samples from Xinyang tea population (Camellia sinensis cv. Quntizhong) taken during processing were systematically analyzed by non-targeted metabolomics. A total of 1 000 non-volatile metabolites were identified, and multivariate statistical analysis showed that non-volatile metabolites changed significantly during the processing stages after fixation. Meanwhile, a total of 53 differential compounds were screened out, including amino acids, catechins, flavonoid glycosides, lipids, purine nucleosides and organic acids that were identified as the key components contributing to the flavor and quality of Xinyang Maojian tea. In particular, the relative contents of some acylated flavonoid glycosides, lysophosphatidyls and purine nucleosides were significantly elevated during the processing stages after fixation. Kyoto Encyclopedia of Genes and Genomes (KEGG) metabolic pathway enrichment analysis showed that the differential compounds were significantly enriched in the pathways of purine metabolism, glycerophospholipid metabolism, phenylalanine metabolism, aminoacyl-tRNA biosynthesis, phenylalanine, tyrosine, and tryptophan biosynthesis, and glycine, serine and threonine metabolism (P < 0.05). This study provides a basis for understanding the formation mechanism of the flavor and quality of Xinyang Maojian tea.

Keywords

• non-targeted metabolomics; xinyang maojian tea; tea processing; non-volatile metabolites