四川茶树品种资源中EGCG3″Me研究
Analysis of 3″-Methyl-epigallocatechin gallate in Sichuan tea varieties resources
-
摘要: 采用高效液相色谱法(HPLC)对四川70份茶树品种资源新梢中(-)-表没食子儿茶素-3-O(3-O-甲基)没食子酸酯(EGCG3″Me)含量进行分析,发现3份茶树品种资源富含EGCG3″Me(含量>10 mg/g),即蜀茶5号、金观音、城西11号。对蜀茶5号新梢季节及叶位变化规律研究,发现春、夏、秋三季,随着新梢叶片成熟,EGCG3″Me含量均先增加后降低;同等叶位相比,EGCG3″Me含量均呈递增趋势;含量最高的叶位为秋梢第二叶,秋梢第一叶至第四叶均超过10 mg/g。以蜀茶5号秋梢加工成4种茶类,发现绿茶、黄茶中EGCG3″Me含量最高,与鲜叶相当,其次为青茶,而红茶中未检出,且萎凋显著增加其含量。建议四川富含EGCG3″Me茶叶将秋梢一芽二、三叶加工成绿茶或黄茶,且在加工前进行适度摊放(轻度萎凋)。Abstract: 3″-Methyl-epigallocatechin gallate(EGCG3″ Me) in the young tea leaves of 70 major tea varieties resources in Sichuan were analyzed using HPLC. The results revealed that Shucha 5,Jinguanyin,Chengxi 11 were found to contain higher levels of EGCG3″Me(>10 mg/g). The EGCG3″Me levels of different positions of tea line Shucha 5 ‘five and a bud' shoots from spring to autumn were also analyzed. The results showed that the contents of EGCG3″ Me presented first an increasing and then a decreasing trend with the leaf maturity.Compared with the same leaf order,EGCG3″Me contents were increasing. The second leaf in autumn were the highest,the first to the fourth leaves were more than 10 mg/g. The fresh tea leaves in autumn of Shucha 5 were processed to four different types of teas,The EGCG3″Me levels of green tea and yellow tea were the highest,similar to fresh tea leaves,followed by oolong tea. However,black tea do not contain detectable EGCG3″ Me.The content of EGCG3″ Me increased distinctly during withering. Based on these results,a better way to produce tea leaves rich in EGCG3″Me was proposed,which includes picking fresh tea leaves with two or three leaves and a bud in autumn,processed to green tea or yellow tea,modest spreading(mild withering) before processing.