Insight into effects of isolated Eurotium cristatum from Pingwu Fuzhuan brick tea on the fermentation process and quality characteristics of Fuzhuan brick tea

BACKGROUND: Pingwu Fuzhuan brick tea is a type of post-fermented tea manufactured from leaves of tea plant, Camellia sinensis var. sinensis, of which the quality is influenced by numerous factors, especially microorganisms. Currently, there is little research on the effect of microorganisms on the fermentation and quality characteristics of Pingwu Fuzhuan brick tea. Investigation of main fungus in Pingwu Fuzhuan brick tea and its effect on fermentation process and tea quality can provide insights into manufacturing of "western road" border-selling tea and lay a foundation for popularization of Pingwu Fuzhuan brick tea. RESULTS: The main "golden flower fungus" in Pingwu Fuzhuan brick tea was isolated and identified as Eurotium cristatum (GenBank accession number: MF800948.1; strain PW-1). Compared with natural fermentation, PW-1 inoculated fermentation accelerated biotransformation of phenolic compounds, which imparted tea samples with better taste and tea infusion color. The proportions of velvety-like and sweet-tasting amino acids were increased after 16-day fermentation with PW-1. Alcohols were the most abundant volatiles, of which the contents were 40.13% and 39.43% in NF16d and IF16d tea samples. The orthogonal partial least squares discriminant analysis (OPLS-DA) and hierarchical clustering analysis (HCA) further revealed naturally and PW-1 fermented teas were significantly different. CONCLUSION: Strain PW-1 plays an important role in the fermentation process of Fuzhuan brick tea. Considering fermentation efficiency and tea quality, fermentation inoculated with E. cristatum PW-1 can be applied in the manufacturing of "western road" border-selling tea. This article is protected by copyright. All rights reserved.