优510白茶加工过程主要生化成分变化研究

Major Biochemical Changes of You 510 Tea Leaves During Processing

选用乐昌白毛茶天然杂交后代优510鲜叶为原料,观测其在白茶加工过程中的主要生化成分变化规律及其与品质的关系,结果表明,萎凋56h后进行烘干,成品白茶带甜香、滋味清甜,白茶品质风格明显。在白茶萎凋过程中,叶片水浸出物总量在萎凋24h时达到最高,之后随萎凋进行显著下降;萎凋叶茶多酚总量在萎凋12h时达到最高,之后随萎凋进行不断下降;萎凋叶咖啡碱含量在萎凋48h时达到最高,但整个萎凋过程中咖啡碱含量没有显著起伏;叶片中儿茶素组分EC、EGC和EGCG含量也均在萎凋12h时达到最高,GA含量则在萎凋48h时达到最高,C和ECG含量总体上均随萎凋进行不断下降;叶片氨基酸总量经历了极显著升高然后不断下降的过程,氨基酸总量在萎凋12h时最高,在萎凋48h时最低,茶氨酸含量的变化趋势也是如此,而γ-氨基丁酸含量在整个白茶加工过程中一直呈现极显著上升的趋势。

You 510,a natural hybrid offspring of Lechang Baimaocha cultivars,was the tea plant from which the leaves were used for this study.The major biochemical changes in the leaves during processing and their possible relationship with the resulting white tea quality were investigated in order to optimize the processing technology.During the tea-making process,the picked fresh leaves were first withered 56 h,then dried.The white tea typically smells and tastes sweet with the characteristic aroma.The soluble solid content of the tea＇s water extract reached a maximum at 24th hour of wilting.It,then,descended significantly with continued wilting.The total polyphenols in the tea leaves peaked after wilting for 12 h,followed by a gradual decline with wilting.The caffeine content in the leaves reached the highest at 48 h,without appreciable fluctuations during the entire wilting process.Content of catechins,such as EC,EGC and EGCG,was at its highest after wilting for 12 h.On the other hand,GA content was at its highest at 48 h,and both C and ECG declined with wilting progressed.The total amino acids of the withered leaves significantly increased initially to peak at 12 h,then decreased to a minimum at 48 h.Theanine appeared to change in a similar manner.The content of GABA was found to significantly and continuously increase throughout the process.