Abstract:

Fermentation is a critical procedure in black tea manufacture. In order to improve the quality of black tea, we
attempted to utilize the polyphenol oxidase from Pyrus pyrifolia Nakai to improve the fermentation process and thus investigated
the sensory quality, color and main taste and aroma components of the resulting black tea in the present study. Results indicated
that this new treatment significantly improved the sensory quality of black tea. As compared with those of the control, the
brightness of tea infusion was increased significantly (P ＜ 0.01) and the ratio of theaflavins to thearubigins and the content of
soluble sugars in black tea treated with a ratio of crude polyphenol oxidase solution to rolled tea were increased by 86.05% and
34.34%, respectively, whereas the ratio of polyphenol to amino and the content of flavonoids were decreased by 3.96% and 7.35%,
respectively. The aroma components β-ionone, trans-geraniol and α-copaene were increased.

Key words: black tea in summer and autumn, polyphenol oxidase, taste, color, aroma