Effects of Microbial Action and Moist-Heat Action on the Nonvolatile Components of Pu-Erh Tea, as Revealed by Metabolomics

  • J Agric Food Chem. 2022 Nov 28. doi: 10.1021/acs.jafc.2c05925.
Tiehan Li  1  2 ,  Yiyi Zhang  1  2 ,  Huiyan Jia  1  2 ,  Jixin Zhang  1  2 ,  Yuming Wei  1  2 ,  Wei-Wei Deng  1  2 ,  Jingming Ning  1  2
Affiliations
  • 1. State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, 130 Changjiang West Road, Hefei230036, Anhui, China.
  • 2. School of Tea and Food Science and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei230036, China.
PMID: 36441948 DOI: 10.1021/acs.jafc.2c05925
Abstract

Microbial action and moist-heat action are crucial factors that influence the piling fermentation (PF) of Pu-erh tea. However, their effects on the quality of Pu-erh tea remain unclear. In this study, the effects of spontaneous PF (SPPF) and sterile PF (STPF) on the chemical profile of Pu-erh tea were investigated for the first time, and sun-dried green tea was used as a raw material to determine the factors contributing to the unique quality of Pu-erh tea. The results indicated that the SPPF-processed samples had a stale and mellow taste, whereas the STPF-processed samples had a sweet and mellow taste. Through metabolomics-based analysis, 21 potential markers of microbial action (including kaempferol, quercetin, and dulcitol) and 10 potential markers of moist-heat action (including ellagic acid, β-glucogallin, and ascorbic acid) were screened among 186 differential metabolites. Correlation analysis with taste revealed that metabolites upregulated by moist-heat and microbial action were the main factors contributing to the staler mellow taste of the SPPF-processed samples and the sweeter mellow taste of the STPF-processed samples. Kaempferol, quercetin, and ellagic acid were the main active substances formed under microbial action. This study provides new knowledge regarding the quality formation mechanism of Pu-erh tea.

Keywords
Pu-erh tea; metabolomics; microbial action; moist-heat action; quality.
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