蓝光、红光对工夫红茶萎凋中鲜叶氨基酸和儿茶素组分含量的影响

摘要

系统研究了不同光质（蓝光、红光和无光）对工夫红茶萎凋过程中氨基酸和儿茶素组分含量变化趋势及成品茶感官品质的影响。结果表明，随着萎凋时间的增加，鲜叶氨基酸含量除茶氨酸和天冬氨酸下降、谷氨酸先增加后下降外，氨基酸总量及其余组分均增加；红光处理天冬氨酸和茶氨酸降低程度最大，异亮氨酸、亮氨酸、酪氨酸、赖氨酸、组氨酸增加明显，而丝氨酸、缬氨酸、苯基丙氨酸无光处理组增加明显，其余氨基酸在蓝光处理下增加明显。鲜叶中没食子儿茶素（GC）、表没食子儿茶素（EGC）、表儿茶素没食子酸酯（ECG）、表没食子儿茶素没食子酸酯（EGCG）、酯型儿茶素及总儿茶素含量随萎凋时间的增加而降低，但儿茶素（C）、没食子酸儿茶素没食子酸酯（GCG）、儿茶素没食子酸酯（CG）含量随萎凋时间的增加呈先增加后降低，表儿茶素（EC）含量却随萎凋时间的增加先降低后增加；红光处理的 GC、EGC、EGCG、酯型儿茶素及儿茶素总量降低程度最大；与无光处理相比，红光和蓝光处理均能显著降低 ECG 的含量。同时，红光和蓝光萎凋处理的成品茶感官审评得分高于无光处理，且红光组香气因子得分高，蓝光组滋味因子得分高。由此可见，不同光质能影响鲜叶萎凋过程中儿茶素和氨基酸组分含量变化，并影响成品茶品质，红光萎凋品质最优。%Effect of light-exposure (i.e.,red,blue or no light)during the withering process of Congou black tea was studied.Contents of amino acids and catechins of the tea leaves were monitored,and the sensory evaluation on the steeped tea performed.The results showed that the total and most amino acids,except Asp and Thea,in the leaves increased gradually during the withering process.Exposed under the red light,Asp and Thea in the leaves decreased,while Ile,Leu,Tyr,Lys and His increased in greater extents than other amino acids.When no light was applied,Ser,Val and Phe in the leaves increased most significantly.Withering under the blue light,the tea leaves contained significantly greater amounts of the rest of amino acids than under either the red light or no light.The contents of GC, EGC, ECG, EGCG, total esters type catechins and total catechins in the leaves decreased gradually upon withering,while those of C,GCG and CG increased at the beginning and then decreased afterward. During the spreading of the leaves for withering,EG decreased initially and then increased.Exposed under the red light,the tea leaves contain less of GC,EGC,EGCG,total esters type catechins and total catechins than other lighting conditions.Either the blue or red light exposure reduced more ECG than total darkness.The sensory evaluation on the brewed tea showed that the Congou black tea withered under the red light had the highest score on aroma,and that withered under the blue light had the highest score on taste.It appeared that the light-exposure during withering could affect the amino acid and catechins contents of the teas.Congou black tea withered under the red light seemed to have the best quality among all samples.