Effects of different de-enzyming methods on microbial composition and volatile compounds of raw Pu’ er tea based on microbiome and metabolomics

Microorganisms play a significant role in the quality formation of raw Pu' er tea, and volatile compounds mainly contribute to the aroma quality. However, different de-enzyming methods on the quality of raw Pu' er tea has not yet been reported. Microbiome and metabolomics were employed to comprehensively compare and analyze microbial community and volatile compounds in machine de-enzyming raw Pu' er tea (JS) and manual de-enzyming raw Pu' er tea (SS) in this study. High-throughput sequencing results showed that bacterial and fungal community compositions of JS and SS samples at phylum and genus levels were essentially identical, differed in relative abundance. A total of 65 and 71 volatile compounds were detected and characterized in JS and SS samples, respectively. Volatile components in JS and SS samples were mainly composed of alcohols, esters, aldehydes, alkanes, benzene and its derivatives, ketones, alkenes, phenols. A total of 88 differential volatile components between JS and SS samples were screened based on VIP >1 and p-value < 0.05. Those results indicated that both microbial community composition and volatile compounds in raw Pu' er tea influenced by different de-enzyming methods. This work helps reveal the effect of different de-enzyming methods on the quality of raw Pu' er tea and provide a scientific reference basis for the improvement of raw Pu' er tea quality.