【作者】 胡祥文；

【导师】 甘霖； 廖振坤；

【作者基本信息】 湖南农业大学 ， 种植， 2003， 硕士

【摘要】 近年来，随着人们生活质量的提高、保健意识的增强以及对名优产品需求的增加，名优绿茶的产量、产值在逐年增加。但是，茶叶是一种季节性生产、全年消费的产品，尤其是名优绿茶主要集中在多雨高湿的春季生产，若不进行保鲜处理，名优绿茶很快就会失去应有的品质风味与保健效果。目前，应用于名优绿茶的保鲜方法大多是采用去湿、除氧、抑菌等单因子保鲜措施，效果不够理想，尤其是各保鲜技术的具体技术参数缺乏系统性和可操作性。为此，深入研究名优绿茶贮藏过程中品质劣变的机理，并据此控制名优绿茶贮藏过程中的环境反应因子，筛选出较好的高效复合保鲜方法，有着重要的理论及实践意义。 本研究分两个阶段进行。第一阶段选用2001年春季郴州一芽一叶加工而成的名优绿茶为原料，将多种去湿剂和除氧剂合理配方，配制了16种茶叶保鲜剂，并对该名优绿茶进行三个月的破坏性试验，以筛选出较优的复合保鲜剂。第二阶段选用2002年春季郴州一芽二叶加工而成的名优绿茶为原料，选择了3个低温（-15℃、0℃、4℃）及室温（CK1）四个温度梯度，并与第一阶段筛选出的3种较优保鲜剂和不装保鲜剂（CK2）四个保鲜处理复合成16个处理进行贮藏保鲜试验。本研究系统研究了名优绿茶品质劣变机理、温度单因子的保鲜效果、保鲜剂单因子的保鲜效果以及温度与保鲜剂的复合保鲜效果。结果表明： 1．名优绿茶破坏性贮藏3个月后，香气、汤色、滋味、亮度、透光率以及各内含成分不同程度地劣变或下降；各复合保鲜剂对名优绿茶均有一定的保鲜效果，其中以i（变色硅胶+维生素C），j（变色硅胶+铁粉），m（焦亚硫酸钠+维生素C）三处理的保鲜效果较好。 2．名优绿茶在室温不内装保鲜剂贮藏过程中，物理性状、主要生化成分含量、感官品质都随贮藏时间的延长而下降或劣变。L（茶汤亮度）、T₆₄₀（茶汤透光率）在贮藏期间持续下降，茶汤色泽a、b值持续上升且幅度较大；生化含量的下降幅度是简单儿茶素＞茶多酚＞酯型儿茶素＞咖啡碱＞水浸出物，且以贮藏前两个月的变化幅度最大；氨基酸在贮藏前六个月持续减少，后期呈起伏变化，游离氨基酸的含量大约维持在2.00%;水分在贮藏过程中持续上升，但上升幅度不是很大，年贮藏过程中水分含量由贮藏前的6.07%上升至6.41%。感官品质在整个贮藏过程中，下降幅度一_直较大、 3.名优绿茶在低温不内装保鲜剂处理较cKl（室温）有较好的保鲜效果;低温保鲜处理间也有显著差异，并以一巧℃贮藏较好;一巧℃保鲜处理的常规生化成分在货架期第一个月比第二个月的变化幅度大，O℃、4℃、CKI在货架期第二个月比第一个月的变化幅度大;但一巧℃、O℃、4℃处理保鲜对儿茶素在货架期第一个月比第二个月的变化幅度大，而CKI货架期第二个月比第一个月的变化幅度稍大。 4.3种较优保鲜剂应用在名优绿茶室温贮藏保鲜中较CKZ（未装保鲜剂）有明显的保鲜效果;内装保鲜剂处理的年平均含水量较CKZ低，比贮藏前的原料样的含水量低;不同保鲜剂处理的茶样在贮藏过程中各生化组分的保留量上有显著差异，以保鲜剂②（焦亚硫酸钠+维生素C）处理较佳，各内含成分较高，其感官品质也高于其他保鲜处理。 5.温度与保鲜剂的复合保鲜效果要优于单因子低温保鲜或保鲜剂保鲜;在贮藏期间，以F处理〔O℃十保鲜剂③（变色硅胶十维生素c）〕最好，E[0℃+保鲜剂②（焦亚硫酸钠十维生素c）]、H卜巧℃+保鲜剂②（焦亚硫酸钠十维生素c）]、G卜巧℃+保鲜剂①（变色硅胶十铁粉）〕、I[一15℃十保鲜剂③（变色硅胶+维生素c）』处理次之;但F处理在货架期里变化幅度很大，经过两个月的货架期处理后，以H处理较好，其次为E、G、I处理。更多还原

【Abstract】 In recent years, with the improvement of people’s living standards, the enhancement of health care consciousness and the increase of demanding in famous quality products, the yields and the value of famous quality green tea are increasing year by year. However, tea, especial famous quality green tea is a seasonal product and consuming in the whole year, if it could not be keeped in correct way ,it would lose the original character quickly. Most of the methods for keeping freshness of famous quality green tea could not work very well as the lack of the technique parameters for keep freshness. Therefore, it is very important to the deterioration mechanism during the storage period and screen out the efficient method for keep freshness of famous quality green tea fresh by controlling the environmental factor.By using the famous quality green tea, made of one bud and one leaf in Spring of 2001 in the Improved Variety Tea Plant Farm of Chenzhou of Hunan Province, and preparing the keeping freshness agents by combining the drying agent and antioxidant agent , three damaged storing experiments of months aiming at screening the high efficient keeping freshness agents for the tea were carried out at the first step. Then by using the famous quality green made of one bud and two leaves in Spring of 2002 in the Improved Variety Tea Plant Farm of Chenzhou of Hunan Province, choosing three kinds of low temperature and CK1 (normal atmospheric temperature), three keeping freshness agents and CK2(no keeping freshness agent), compose 16 treatments for storage experiments. The mechanism of deterioration, the keeping freshness effects of temperature, keeping freshness agents and their combination were comprehensively studied. The results showed that:1. After three months of damaged storing experiment, it reveals that the fragrance, infusion color, taste, brightness, transparency and the content of biochemical component of the tea went bad or were reduced differently, and all the agents had some effect on keeping the famous quality green tea freshness. Among the agents, Silical gel+Vitamin C, Silical gel+Iron powder and Sodium pyrosulphate+Vitamin C are much better.2. During the storage in a year, the physical indexes, biochemical indexes, sensory quality of famous quality green tea were deteriorating. L T640 declined continuously, and a, b increased continuously and quickly. The declining range of the biochemical content is that the simple catechins >tea polyphenols>estered catechins >caffeine>water extracts ,and they varied quickly in the first two months The free amino acid declinedcontinuously in the first six months;later, it varied undulately, and the residual content maintain about 2.00%. The content of the moisture rose from 6.07% to 6.41%.That is to say ,the extents of the variation wasn’t very large. The sensory quality deteriorated heavily!3. Compared to the lower temperatures and CK1, the lower temperatures could keep the famous quality green tea fresh in some extent,but they also existed the obvious variances among the lower temperatures, -15C preservation well. On the condition of -15C, the main biochemical indexes varied more quickly in the first month than in the second month when they were on the shelves ,it were opposite when on the condition of CK1.4.Three kinds of prior keeping-fresh agents had the obvious fresh effect When compared to CK2. The content of the average of moisture were cower than CK2 When use the keeping-fresh agent, even lower than the original content. Multiple comparisons reveal that there were significant variances of each biochemical indexes among these four treatments, besides, the keeping-fresh agent of No. 2 is better than others.5. The effects of keeping fresh by the compound method is prior to the single factor methods; During the storage period, treatment F could retain the original character at the most degree, E, H, G, I treatments come second, but F treatment dropped badly during the period of shelves. All in all, H treatment is better than others.更多还原