不同光波晒青对单枞茶品质的影响

Effects of Withered with Different Light-Wave Bands on Qualities of Dancong Tea

晒青是乌龙茶制造的关键工序,但晒青易受天气条件的限制,导致了春季多雨与单枞茶鲜叶高产、质优,却难以发挥其优良品质的矛盾;用几种滤光材料,从日光中获得连续的光波段对单枞茶进行晒青,以期找出较佳的光波段,为人工模拟日光萎凋、实现全天候人工控制晒青提供理论基础。研究结果显示:与茶鲜叶相比,5种光处理晒青叶中品质成分含量变化趋势一致,但变化幅度不一致。去紫外光膜(透过的波长大于400 nm)的处理晒青叶的多酚类物质保留量最多,而醚浸出物的减少量最大;黄色滤光膜(透过的波长大于520 nm)的处理晒青叶中氨基酸的增加量最多;毛茶品质成分,以黄色滤光膜处理多酚类含量、氨基酸含量、水溶性糖含量、醚浸出物含量均为最高,其品质得分最高;去紫外光膜处理氨基酸含量、水溶性糖含量、醚浸出物含量均较其它处理低,而酯型儿茶素/简单儿茶素的值较其它处理高。全光谱和透红外膜(透过的波长大于720 nm)处理毛茶中品质成分含量均居中,与毛茶感官审评结果中两处理品质相当一致。

Four light-wave bands of different wavelength, i. e. longer-720 nm, longer-640 nm, longer-520nm, longer-400nm were used in withering process of Oolong tea. The analysis of biochemical substances of the withered leaves and raw tea showed that： The tendency of biochemical substances of withered leaves in the four treatments was similar, the contents of polyphenols and ether dissolved substance decreased, while the contents of ammo acids and the water-dissolved sugars increased. Withered with different light-wave bands, the raw tea showed different qualities. The analyses of the bio-chemical substances showed that the wavelength-longer-640 nm-band was favorable to the qualities with higher contents of polyphenols, ether soluble substance and amino acids. While the wavelength-longer-400 nm-band treatment had the lowest polyphenols, amino acids, other soluble substances and the highest ratio of complex cateehins to sample ones. The sensory tasting of raw tea was consistent with the analytic results of bio-chemical substances, which showed the raw tea withered with longer-520 nm light bands had the highest score for its high aroma and mellow, brisk tasting; the raw tea withered with longer-400 nm resulted the lowest score for the thinner aroma and bitter tasting.