电子鼻技术在不同厂家特种茉莉花茶香气判别中的应用研究

目的探讨i Nose型电子鼻在区分和判别特种茉莉花茶香气的可行性和效果。方法以福州特种茉莉花茶为对象,以i Nose型电子鼻传感器的响应值为指标,对不同厂家、不同外形的特种茉莉花茶进行判别分析。结果主成分分析结果显示,两个厂家的成品茉莉花茶能够被有效区分;同一厂家不同外形成品茶间香气风格相近,故区分不明显;窨制过程样与成品茶的香气品质存在差异,故被有效地区分。电子鼻响应值能够实现对同一外形不同厂家间、不同窨次间的区分,但区分效果因外形而异。Fisher判别分析显示,本文建立的判别函数,其回代验证正判率达到100.0%,交叉验证正判率为86.1%。结论电子鼻技术可用于特种茉莉花茶香气品质的区分和识别,可为茉莉花茶窨制工艺、产品质量控制模型的建立提供理论依据。     

逆境下茶树叶绿体的理化特征研究进展

在逆境下,茶树叶绿体脂质过氧化程度加剧,会积累较多丙二醛,增强超氧化物歧化酶活性;活性氧代谢改变,致使抗氧化酶活性升高,一些毒害类物质(O_2~-、H_2O_2等)增多,一些非酶抗氧化性物质减少;并且叶绿体的类囊体和基粒片层等超微结构也发生变化。同时,通过施用抗坏血酸等外源物质能一定程度上减轻逆境对叶绿体造成的损伤。然而,有关茶鲜叶中的叶绿体在加工中的变化特征研究相对较少,不利于深度解析机械胁迫对乌龙茶品质的影响。本文通过对茶树叶绿体的生理生化响应特征的阶段性研究文献综述,阐明水分胁迫、光照胁迫、氟胁迫等非生物胁迫对茶树叶绿体的影响。本文进行乌龙茶加工中叶绿体的理化特征研究,期待从细胞器水平上研究乌龙茶加工原理。     

Changes in enzyme activities (polyphenol oxidase and phenylalanine ammonia lyase) with type of tea leaf and during black tea manufacture and the effect of enzyme supplementation of dhool on black tea quality

Variation in polyphenol oxidase (PPO) and phenylalanine ammonia lyase (PAL) activities with respect to different cultural and manufacturing processes and their effects on black tea quality were studied. There was a wide variation between enzyme activities of different clones, as well as variation due to seasonal changes and shoot maturity. Field practices such as plucking rounds and pruning had a great impact on enzyme activities. The enzyme activities positively correlated with tasters' scores. The extent of change in enzyme activities at different stages of manufacture differed widely. The loss of activity during withering could be restored by rehydration. Residual activity was observed in made tea. Supplementation of enzymes enhanced the black tea quality markedly in terms of cuppage and creaming properties.     

特种茉莉花茶及其品质影响因素的研究现状

随着消费水平的日益提高,特种茉莉花茶已成为茉莉花茶市场的新宠。本文对现有特种茉莉花茶的产品和特点进行了总结,并对影响特种茉莉花茶品质的形状特征、窨制方法(传统窨制、增湿连窨、隔离窨花等)、窨制参数(水分、温度、配花量等)等因素研究现状进行了阐述。特种茉莉花茶具有独特的外形、鲜灵持久的花香和鲜醇爽口的滋味,销量和价格均日渐上涨,然而,对其加工工艺的研究多以生产经验为主,理论基础较薄弱。为此,本文提出了应针对特种茉莉花茶的理化性状,加强其窨花理论的系统化研究,同时重视对老化茉莉花园的改造和新品种茉莉花的选育工作,从而促进特种茉莉花茶可持续健康发展的建议。