Comparison of characteristic components in tea-leaves fermented by Aspergillus pallidofulvus PT-3, Aspergillus sesamicola PT-4 and Penicillium manginii PT-5 using LC-MS metabolomics and HPLC analysis

Microbiota influenced quality formation of ripened Pu-erh tea. To understand the effect of each tea-derived fungal strain, tea-leaves were fermented by Aspergillus pallidofulvus PT-3 (ApaPT), Aspergillus sesamicola PT-4 (AsePT) and Penicillium manginii PT-5 (PmaPT), respectively. 14 Phenolic compounds, 3 purine alkaloids, 19 free amino acids and γ-aminobutyric acid contents were determined by HPLC and amino acid analyzer analysis. Additionally, UHPLC-Q-TOF/MS method was developed for LC-MS metabolomics analysis. Multivariate statistical analyses, such as PCA and HCA, exhibited that the chemical profile of PmaPT fermentation was similar to biocidal treatment, but had significant differences with ApaPT and AsePT fermentation. The differentiated metabolites (VIP > 1, p < 0.05 and FC > 1.50 or < 0.66) and one-way ANOVA revealed the impact of three fungal strains in tea-leaves fermentation. APaPT and AsePT contributed to biosynthesis of gallic acid and several flavonoids, such as kaempferol, quercetin and myricetin in the metabolism of phenolic compounds.