Effect of Fungal-fermentation Process on Flavor Quality in Different Grades Vine Tea

In order to explore the effect of fungal fermentation on the flavor quality of different grades of vine tea, hand-made Fu brick tea was processed from first-class vine tea and second-class vine tea. Sensory evaluation, physical and chemical composition analysis and aroma component comparison were contrasted. The results showed that fungal fermentation reduced the bitterness of different grades of vine tea, changed the aroma from grass aroma to the flower-fruit aroma, and had a unique fungal fragrance, and the soup color changed from bright yellow to bright orange. The contents of water extracts of the two fermented vine teas remained basically unchanged, and the contents of free amino acids and soluble sugars decreased to varying degrees. Particularly, the contents of free amino acids decreased significantly by 48.54% and 38.57%, respectively (P<0.05). The content of dihydromyricetin increased significantly from 312.80 mg/g and 154.56 mg/g before fungal fermentation to 371.26 mg/g and 161.00 mg/g, respectively. The content of myricetin in fungal fermentation first-class vine tea increased and decreased in fungal fermentation second-class vine tea. The contents of trans-2 hexenal, (E)-2-heptene aldehyde and trans-2-decene aldehyde with fresh grass aroma, and 1-octene-3-alcohol with soil odor in the two fungal fermentation vine teas decreased or disappeared. The contents of farnesol, phenylacetaldehyde, safflower aldehyde, farnesyl acetone, methyl heptenone, methyl salicylate, and dihydroanisole with flower aroma, fruit aroma, and medicine aroma increased or appeared. Among them, the relative contents of 2-cyclohexene-1-one, β-ionone, geranyl acetone, dihydrogen-γ-ionone and ethyl palmitate with flower and fruit aroma increased significantly in fungal fermentation second-class vine tea. Therefore, after the fungal fermentation of vine tea, the green grass aroma is weakened, showing the characteristics of flower and fruit aroma.