Characterization of the key aroma compounds and microorganisms during the manufacturing process of Fu brick tea

Aroma is one of the most important criteria of tea quality, but the dynamic changes of aroma profile during the manufacturing process, and the chemical basis of characteristic aroma in Fu brick tea remain largely unknown. In this study, a total of 72 volatiles were identified and quantified, only the esters content increased sharply during the process. Sensory quantitative description analysis revealed that the 'green' attribute was dominated in the early processing stage, and the 'fungal flower', 'flower', 'mint' and 'woody' attributes became the major contributors to the aroma character in the later processing stages. Indicated by partial least-squares analysis, the linalool, acetophenone, and methyl salicylate were identified as key volatiles contributors to the 'fungal flower', 'flower', and 'mint' attributes, the cedrol contributed to 'woody' attribute, and twelve alcohols and aldehydes were related to 'green' attribute. Besides, bidirectional orthogonal partial least squares analysis revealed that six fungal genera Aspergillus, Candida, Debaryomyces, Penicillium, Unclassified_k_Fungi, Unclassified_o_Saccharomycetales were identified as core functional microorganisms link to the metabolism of volatiles. Taken together, these findings provide new insights into Fu brick tea aroma profile variation and increase our understanding of the formation mechanism of the characteristic aroma during the manufacturing process.