基于滋味成分变化的祁门红茶发酵程度差异研究

Research on the Difference of the Fermentation Degree of Keemun Black Tea Based on the Changes of Taste Components

为探究不同发酵程度祁门红茶的滋味成分变化规律,筛选区别祁门红茶发酵程度的差异滋味成分,测定了祁门红茶样品中主要滋味成分的含量,结合感官审评,利用剂量比阈因子(Dose-over-threshold factors,DoT)分析与正交-偏最小二乘判别分析(Orthogonal partial least squares-discrimination analysis,OPLS-DA)进行综合分析。结果表明:在舒茶早和凫早2号两个品种红茶样加工过程中,随着发酵进程,茶黄素总量稍有增加,分别从8.65mg/g和4.10 mg/g增加到8.66 mg/g和5.52 mg/g;游离氨基酸总量降低,发酵偏重(Ⅲ)的氨基酸总量为82.98 mg/g和80.23 mg/g,比发酵偏轻(I)的分别降低31.2%和9.4%;儿茶素总量显著下降,相对于发酵偏轻(Ⅰ),发酵偏重(Ⅲ)的分别下降63.26%和62.43%,且下降速度发酵适度(Ⅱ)快于发酵偏重(Ⅲ);咖啡碱较为稳定。儿茶素含量减少,茶黄素含量增加,形成发酵适度(Ⅱ)茶样醇厚爽口的品质。利用Dot和OPLS-DA筛选到3种贡献差异物质,分别是GA、TFDG和TF-3-G,其中GA的贡献值大于其余茶黄素组分。

To investigate the changes of taste components in Keemun black tea with different fermentation levels,and screen the different taste components that distinguish the fermentation degree of Keemun black tea,the content of main flavor components in Keemun black tea with different fermentation degrees were determined in this study.Sensory evaluation,dose-over-threshold factors,orthogonal partial least squares-discrimination analysis were used to conduct a comprehensive analysis.The results showed that the total amount of theaflavin in Shuchazao and Fuzao 2 increased slightly with the fermentation process,from 8.65 mg/g and 4.10 mg/g to 8.66 mg/g and5.52 mg/g,respectively.The total amount of free amino acids decreased.The content of amino acids with heavy fermentation (Ⅲ) was 82.98 mg/g and 80.23 mg/g respectively,which were 31.2% and 9.4% lower than that with light fermentation (I).The total content of catechins decreased significantly.Compared with the light fermentation (I),those with heavy fermentation (Ⅲ) decreased by 63.26% and 62.43%,respectively.And the decline rate of moderate fermentation (Ⅱ) was faster than that of heavy fermentation (Ⅲ).Caffeine was relatively stable.The content of catechins decreased and theaflavins increased,forming moderate fermentation (Ⅱ) the mellow and refreshing quality.Using Dot and OPLS-DA,three different contribution substances were screened,namely GA,TFDG,TF-3-G,and the contribution value of GA was greater than that of the other theaflavins.