不同摇青方式对秋季绿茶香气的影响

Effects of different shaking treatments on the aroma of autumn tea

中文关键词:  秋茶  摇青  感官品质  品质成分  特征挥发性物质

英文关键词:autumn tea  shaking  sensory quality  quality compounds  characteristic volatile compounds

中文摘要:

      目的 利用乌龙茶的摇青工艺, 探索改善秋季绿茶风味的最佳摇青参数。方法 利用感官审评与定量描述分析, 筛选最佳摇青处理。利用气相色谱-质谱法(gas chromatography-mass spectrometry, GC-MS)获得样品中挥发性物质的组成及含量。利用层次聚类热图分析、偏最小二乘法判别分析(partial least squares- discriminant analysis, PLS-DA), 获得不同处理的特征挥发性物质。结果 摇青整体提高了秋茶得分, 明显改善干茶色泽, 总体改善了茶汤和叶底的颜色、明亮度, 增强了大部分茶样的香气和滋味。摇青提高了秋茶的香气, 其中花香和清香的增强、青草气的减弱是关键, 摇青对栗香和嫩香影响较小; 摇青改变了挥发性物质的组成及含量, 水杨酸甲酯、橙花醇、石竹烯等17种挥发性物质含量的降低及苯乙烯、柠檬烯等15种挥发性物质含量的增加是形成花香型秋茶的关键。结论 秋茶鲜叶摊青6 h后, 15 r/min摇青70转, 静置2 h所制绿茶感官品质最佳。

英文摘要:

      Objective To explore the best shaking parameters for improving the flavor of autumn green tea based on the shaking technology of Oolong tea. Methods Sensory evaluation and quantitative description analysis were used to screen the optical shaking treatment. Gas chromatography-mass spectrometry (GC-MS) were carried out to get the volatile compounds of the samples. Hierarchical clustering analysis and partial least squares-discriminant analysis (PLS-DA) analysis were adopted to explore the characteristic volatile compounds. Results Shaking treatments decreased the content of the total polyphenol, caffeine, soluble sugar, water extract and ratio of phenol to ammonia, and increased the content free amino acids. Shaking improved the aroma of autumn green tea, among which the enhancement of floral and fresh aroma, and the weakening of grassy odor were the key factors, while shaking treatments had few effects on chestnut and tender aroma. Shaking treatments also changed the amounts and content of volatile compounds in samples, and the decrease of 17 kinds of volatile substances such as methyl salicylate, nerol and caryophyllene, and the increase of 15 kinds of volatile substances such as styrene and limonene, were crucial to form the floral scents of autumn green tea. Conclusion The optical shaking parameter explored in this experiment is as follows: Before fixing, spreading for 6 h, then shaking at 15 r/min for 70 revolutions, and let stand for 2 h.