萎凋叶含水量对四川中小叶群体种工夫红茶品质形成的影响

目的探索萎凋程度对重庆工夫红茶品质形成的影响。方法以四川中小叶群体种为研究对象,分析比较了3个萎凋含水量:处理A(69.59%)、处理B(65.17%)、处理C(59.20%)萎凋叶红茶加工过程中色泽、多酚氧化酶(polyphenylene oxide, PPO)活性变化及对后续揉捻效果、生化成分、工夫红茶成茶品质形成的影响。结果随着萎凋水分的降低,萎凋叶L*, b*值呈下降的趋势, a*值呈上升的趋势, 4～6 h时均出现了与总体趋势相反的波动;加工过程中,各处理L*,b*值均呈下降的趋势,a*值在发酵前呈增高的趋势,干燥后值减小。成茶色泽L*a*b*值则均表现为处理A处理C处理B。加工过程中PPO活性呈先升后降的趋势,随萎凋程度的加重,高峰往后延迟且活性越强,处理C在发酵环节中活性最高。揉捻环节随着萎凋叶含水量的降低成条率越高,扁条率越低,细胞破碎率越高,处理C效果最好。内含物质随着萎凋叶含水量的减少,茶多酚先增后减,氨基酸先减后增,咖啡碱呈先减后增再减式起伏变化;水浸出物、可溶性糖差异不明显;成茶中处理C综合感官品质表现最好。结论萎凋叶含水量在60%左右时,有利于发挥四川中小叶群体种品种优势,加工出的工夫红茶品质良好。

Effect of water content of withered leaves on the quality of Congou black tea processed by Sichuan small and medium leaf group species

Objective In order to explore the influence of withering degree on the quality formation of Chongqing Congou black tea.Methods This study made three withering treatments which were water content A (69.59 %), water content B (65.17 %), and water content C (59.20 %), analyzed and compared the color and PPO activity change of the leaves and their influence on the subsequent rolling effect, biochemical composition and the quality formation of Congou black tea with Sichuan small and medium leaf group species. Results The results showed that with the decrease of withered water content, the values of L *, b *of withered leaves decreased, a * increased, and all of them perform an opposite trend during from 4 h~6 h. In the process of processing, the values of L *, b * performing a decreased trend, while the value of a * increased before drying. The values of L * a * b * in the color of Congou black tea were treatment A > treatment C > treatment B. The PPO activity appeared a trend which that first increased and then decreased during the processing. With the increase of withering degree, the later the peak was, the more active it was, and treatment C had the highest activity in the fermentation process. With the decrease of water content of withered leaves, the higher the rate of strip formation, the lower the rate of flat strip, the higher the rate of cell breakage, and treatment C perform the best effect. With the decrease of water content in withered leaves, tea polyphenols first increased and then decreased, amino acids first decreased and then increased, caffeine first decreased and then increased and then decreased; the difference of water extract and soluble sugar was not obvious, the ratio of phenol to ammonia was decreased. The results showed that the tea made under treatment C, in which the content of polyphenols, soluble sugar and phenol / ammonia ratio were the highest, amino acid was in the middle, caffeine was the lowest, and the synthetical sensory quality was the best. Conclusion When the withering water content is about 60%, it is beneficial to give full play to the species advantage of Sichuan Zhongxiaoyezhong, and the processed Congou black tea has good quality.