Abstract:

This study aimed to explore the effects of three combinations of tossing and spreading (totally called Zuoqing)
on Sichuan oolong tea made from fresh leaves of Sichuan tea plant varieties harvested in Spring, Summer and Autumn
by sensory evaluation and chemical composition analysis. The result showed that better tea quality was achieved by four
tossing cycles combined with 9 h of spreading (1 h + 1.5 h + 2 h + 2 h + 1.5 h + 1 h), yielding total sensory scores in terms
of aroma and taste ranging from 56.2 to 61.4. Besides, the total catechin content was reduced by 1.51–9.08 mg/g, while
the relative contents of theaflavins (TFs), thearubigns (TRs) and theabrownines (TBs) were increased by 0.026%–0.043%,
0.39%–0.57% and 0.55%–0.83%, respectively. The oolong tea made from Autumn-harvested tea leaves using this
combination of tossing and spreading scored highest in total sensory scores for taste and aroma, followed by that made
from Spring-harvested tea leaves, and Summer-harvested tea leaves exhibited the lowest score, which were 61.4, 60.0 and
56.2, respectively. This study indicates that the semi-fermentation of tea leaves can be controlled by adjusting Zuoqing,
providing a promising way of improving the quality of Sichuan oolong tea.

Key words: Sichuan Oolong tea, tossing and spreading, tossing number, semi-fermentation, quality