Changes onBiochemical Composition of Chungui Fragrant Black Tea during Fermentation Process

Biochemical composition and sensory quality ofChungui fragrant black tea (Camellia sinensis (L.) O. Kuntze) were studied. Effects of the processing technology on them at various times (i.e., 0, 2, 4, and 6 h) during the fermentation were investigated. As the fermentation proceeded, it was found that the contents of tea polyphenols decreased from 36.1% to 30.77%, water extract from 16.27% to 11.25%, amino acid from 3.54% to 3.2%, and total flavonoids from 8.93% to 7.85%. The contents of theaflavins and thearubigins increased with time, from 0.52% in the beginning to 0.84% at the end, and from 2.26% to 2.58%, respectively. The aromatic constituents of the tea included alcohols, aldehydes, esters, nitrogen compounds, etc. The content of alcohols and nitrogenous compounds decreased, but those of esters, hydrocarbons, and aldehydes increased with increasing fermentation time. The major aromatic compounds in the tea were nerolidol (18.02%), α-Farnesene (12.4%), β-Ocimene (7.89%), indole (6.8%), hexanoic acid-3-hexenyl ester, (Z)-, (5.83%), linalool (5.52%), and geraniol (5.45%), among others. The sensory evaluation on the brewed teas indicated that the tea quality gradually improved with the fermentation. Color of the brewed tea changed from slightly dark orange to brilliant red, the taste from bitter and astringent to sweet and delight, and the aroma from grassy to sweet with floral fragrance.