Effects of fermentation of Eurotium cristatum on the flavor quality of Anji Baicha (Camellia sinensis) based on LC-MS and GC-MS.

Eurotium cristatum is a promising probiotic fungus for improving tea flavor. This research explored the volatile and non-volatile metabolites associated with flavor characteristics of E. cristatum fermented old leaves of Anji Baicha, utilizing e-nose, e-tongue, HS-SPME-GC-MS, and LC-MS. The results indicated that the reduction in bitterness and astringency post-fermentation correlated with the downregulation of catechins, chlorogenic acid, proanthocyanidins, and certain amino acids. The enhanced umami taste was primarily due to the upregulation of gallic acid, adenine, aspartic acid and glutamic acid. GC-MS analysis identified 28 pivotal aroma compounds with OAV > 1, among which β-ionone, 6-methyl-5-hepten-2-one, and 1-octen-3-ol were identified as primary contributors to the distinctive fungal floral scent. Notably, the degradation and oxidation of non-volatile metabolites facilitated the enrichment of volatile compounds. These insights deepen the understanding of metabolite-flavor profile relationship in Anji Baicha fermented by E. cristatum, offering strategies for enhancing added value of old leaves of Anji Baicha.