Dynamical changes of volatile metabolites and identification of core fungi associated with aroma formation in Fu Brick tea during the fungal fermentation

Abstract

Fu Brick Tea (FBT), a distinguished dark tea, derives its unique sensory identity from a specialized fungal fermentation process. However, the effect of core functional fungi on sensory attributes during FBT fungal fermentation still needs to be systematically explored. Employing a synergistic blend of electronic sensory evaluation, microbiomics, and volatile metabolomics, this study delves into the dynamic evolution of fungi and volatile metabolites (VMs) during fungal fermentation. Utilizing fungal sequencing and Gas Chromatography-Mass Spectrometry (GC-MS) techniques, we unveiled 234 OTUs, with g_Eurotium emerging as a dominant fungus. Additionally, we identified 288 contributing VMs, 35 of which exhibited notable fluctuations during fermentation. These associated fungi influenced crucial metabolic pathways, enhancing the synthesis of sweet-scented components like acetophenone, while repressing woody and fecal aromas, exemplified by nerolidol, skatole, and indole. This study reveals the evolution of fungi and VMs during FBT fungal fermentation, and suggests 4 possible pathways of substance synthesis in which fungi may be involved, delivering valuable insights into the nuanced processes governing the quality formation of FBT.