摘要
红茶加工过程中儿茶素会发生歧化和苯骈化反应,萎凋期间叶片的物理和化学变化对后期儿茶素的转化具有一定作用。红茶揉捻开始,儿茶素氧化同时参与歧化反应生成聚酯型儿茶素(Theasinensins,TSs)和苯骈化反应生成茶黄素(Theaflavins,TFs),2类二聚物是儿茶素氧化的主要氧化产物,且均不稳定。通过萎凋程度和萎凋温湿度两部分实验,探究了萎凋对主要儿茶素歧化和苯骈化反应及其产物的影响与机制。研究表明:萎凋条件对2种途径有一定影响,萎凋3~12 h时,时间越长制成的红茶TFs含量越低,TSs含量越高,60%湿度和20℃萎凋处理有利于歧化反应生成TSs;EGCG含量占儿茶素总量的一半上,红茶揉捻期间EGCG氧化的歧化途径高于苯骈化途径,随着发酵时间延长,歧化途径占比逐渐降低,干燥工序中TSs含量升高,TFs含量降低。综合来看,萎凋作为红茶加工不可或缺的一部分,可通过萎凋条件调节儿茶素的歧化和苯骈化反应进程。
During the processing of black tea,catechins of tea leaves would take part in disproportionation reaction and benzoquinone reaction.Withering exerted vital influence on the transformation of catechins.catechins participated in disproportionation reaction and benzoquinone reaction to form TSs and TFs during the processing of rolling,which were main oxidation products of catechins and both of them were unstable.The experiment with different withering time and experiment with different temperature and humidity were carried out.Then the influence of different withering factors on the dimerization of mian catechins as well as their products were analyzed.The research showed that:withering condition had effects on both reaction pathway,when withering under 3~12 h,content of TFs was less while TSs was more during the processing of black tea,and when withering under RH 60%and 20℃,catechins were prone to form TSs.EGCG was more than half of total catechins,the disproportionation oxidation of EGCG was stronger than benzoquinone reaction when rolling,but proportion of disproportionation reaction was lower as fermentation prolonged and content of TSs increased while TFs lower when drying.In general,as a part of procedure of black tea,disproportionation reaction and benzoquinone reaction could be adjusted by controlling withering condition during the processing of black tea.
作者
苏威
王伟伟
江和源
施莉婷
陈琳
付静
崔宏春
SU Wei;WANG Weiwei;JIANG Heyuan;SHI Liting;CHEN Lin;FU Jing;CUI Hongchun(Tea Research Institute,Chinese Academy of Agricultural Sciences,Key Laboratory of Tea Plants Biology and Resources Utilization of Agriculture Ministry,Key Laboratory of Tea Processing Engineering of Zhejiang Province,Hangzhou 310008;Chinese Academy of Agricultural Sciences,Beijing 100081;Shaanxi Province Key Laboratory of Bio- Resources,Shaanxi University of Technology,Hanzhong 723001;Tea Research Institute,Academy of Agricultural Sciences,Hangzhou 310024)
出处
《食品科技》
CAS
北大核心
2019年第7期82-87,共6页
Food Science and Technology
基金
国家自然科学基金项目(31670692)
中国农业科学院科技创新工程项目(CAAS-ASTIP-2016-TRICAAS)
陕西省教育厅重点实验室科研计划项目(18JS016)
关键词
红茶
萎凋
聚酯型儿茶素
茶黄素
聚合
black tea
withering
theasinensins
theaflavins
polymerization
