"Golden flower" development of Aspergillus cristatus determined the sensory characteristic and aroma compounds of Fu brick tea.

Golden flower produced by Aspergillus cristatus determines the unique quality of Fu brick tea (FBT), but its specific contribution to flavor and the underlying molecular mechanisms remain unclear. Here, strain Y14 with golden flower production and strain W14 unable to form golden flower were isolated and both were identified as Aspergillus cristatus by multigene phylogenetic analysis. Sensory evaluation showed that dark tea fermented by Y14 (TFY) exhibited a mellow and sweet taste with fungal floral aroma, while tea fermented by W14 (TFW) was bitter with a woody aroma. Volatile metabolites were analyzed using HS-SPME-GC-MS/MS, and 1129 volatile compounds were detected. A total of 144 differential volatiles were identified in the TFY_vs_TFW group, which mainly belong to terpenoids, esters, ketones, aldehydes, and heterocyclic compounds. Flavor wheel analysis indicated that golden flower significantly contributed to the sweet aroma of fermented tea. Among the identified key aroma compounds (ROAV ≥ 1), 5-ethyl-3-hydroxy-4-methyl-2(5H)-furanone, (E)-β-damascenone, β-ionone, and 8-nonenal showed higher ROAV in TFY and may be positively associated with its sweet, fruity, and fungal floral characteristics. Comparative genomic analysis revealed that genes related to golden flower development (treB, medA, and sfgA) and flavor metabolism (aryl-alcohol dehydrogenase and mevalonate kinase) exhibited variants in the W14 genome, which may explain the distinct golden flower phenotype and fermented tea flavor between TFY and TFW. This study highlights the contribution of golden flower to the sensory and aroma quality of FBT.