Abstract: This study investigated the effect of self-isolated and purified strain LJSC.2006 on the quality of Hunan Fu tea, a primary dark tea. Strain LJSC.2006 was identified as Aspergillus cristatus (Aspergillus cristatus LJSC.2006, GenBank accession number: MZ147025) through colony plate morphology, spore electron microscopy, and mycelial molecular marker identification. Sensory evaluation, biochemical composition analysis and head space solid phase microextraction/gas chromatography-mass spectrometry methods were applied to assess the flavor and aroma qualities of dark tea raw materials and fermented Jinhua loose tea. The results indicate that compared with the primary dark tea, the fermented loose tea sample exhibited a deeper color, the golden flowers, a richer fungus aroma, and a mellower taste. After fermentation by Aspergillus cristatus LJSC.2006, there was a decrease in the levels of flavor quality components such as tea polyphenols, soluble carbohydrates, free amino acids, flavonoids, ester-catechins, myricetin, quercetin and kaempferol. The aroma components, esters and aldehydes of the loose tea samples increased after fermentation. Styrene and cedrol were the common aroma components in the primary dark tea. (E)-linalool 3,7-oxide and acetophenone were the common aroma components in the fermented loose tea. Additionally, ten characteristic volatile components relative content were significantly increased, including methyl salicylate, (E,E)-2,4-heptadienal, (E)-linalool-3,7-oxide, (E)-furan oxidized linalool, (E)-2-nonanal, (E)-2-hexenal, (E,Z)-6-nonanal, acetophenone, (E)-2-nonanal, and methyl vanillate, which together contributed to the distinctive fungal fragrance of Jinhua loose tea.

Key words: Aspergillus cristatus, fungi strain identification, primary dark tea, Jinhua loose tea, fermented quality