绿茶饮料浸提新方法及陶瓷膜过滤研究

【作者】 时思全；

【导师】 夏涛； 宛晓春；

【作者基本信息】 安徽农业大学 ， 茶学， 2003， 硕士

【摘要】 本论文将微波、超声波应用于茶饮料浸提过程中，研究其对茶叶主要化学成分浸出的影响。结果显示，微波、超声波对茶叶中的主要化学成分有很好的浸出效果，茶多酚、氨基酸、咖啡碱的浸出率分别达到或超过常规浸提法。微波浸提法、超声波浸提法对茶叶中蛋白质、果胶等大分子物质的浸出有抑制作用，检出的蛋白质、果胶含量都低于常规浸提法。微波浸提法所得茶汤汤色较好。 采用HPLC分析了不同浸提方式的茶汤中主要儿茶素含量。结果表明，超声波浸提法所得的茶汤中主要儿茶素含量高于其它浸提方式，尤其EGCG的含量较高。在微波浸提法、超声波浸提法的茶汤中还检测到了D，L-C。研究还发现高温提取可能导致EGCG异构化为GCG。 研究了不同浸提方法提取的茶汤在4℃低温下的抗沉淀效果。结果显示，在低温抗沉淀效果上，超声波浸提法显示出优越性，茶汤保存三个月未出现沉淀。微波浸提的茶汤只能保存一个月，略好于常规浸提法。 采用GC法对不同浸提方法提取的茶汤的香气进行了分析。结果显示，微波浸提法、超声波浸提法有助于香气的浸出，在香气精油总量及种类上都多于常规浸提法。微波浸提法、超声波浸提法提取的茶汤的FI值(香气指数)比常规浸提法也有明显提高。采用β-葡萄糖苷酶酶解释香法对三种不同浸提方法的茶汤中的键合态香气前体进行了研究，结果显示，微波浸提法、超声波浸提法对茶叶中键合态香气前体的浸出有促进作用。 对绿茶提取液进行了陶瓷膜过滤研究。结果显示，初期膜通量下降很快，后期趋于稳定。使用0.2μm的陶瓷膜对茶叶主要化学成分的截留率进行了研究，结果显示对茶汤中的茶多酚、氨基酸、咖啡碱截留率较小，对蛋白质的截留效果最明显。更多还原

【Abstract】 The effects of microwave and ultrasound extracting methods on the main components of tea infusion were studied. The results showed that both methods had a better effect on the extraction of the main components of tea. The contents of tea polyphenols, amino acid and caffeine reached or exceeded those of normal extracting method. They had a retaining effect on the extraction of protein and pectin. The infusion color of tea liquor extracted by microwave method was better..Main kinds of catechins in tea liquors extracted by different extract methods were analyzed by HPLC. The results showed that total amount of catechins in ultrasound extracting infusion were higher than that of other extracting methods, especially the content of EGCG. D,L-C was detected in microwave extracting infusion and ultrasound extracting infusion. EGCG would probably be isomerized to from GCG under high temperatureAnti-sediment effect of infusion by different extracting methods was studied at 4癈. The results showed that ultrasound-extracting infusion had a better anti-sediment effect, which had not produced sediment for three months. Microwave-extracting infusion, which was found sediments after one month, was slightly better than the normal extracting infusion.Aroma in tea infusions with different extracting methods was analyzed by GC. The results indicated that microwave and ultrasound were benefit to the extract of essential oil. Total amount and kinds of essential oil in microwave-extracting and ultrasound-extracting infusion were more than those in normal extracting method. FI in microwave-extracting and ultrasound-extracting infusions increased obviously compared with that of normal extracting method. Glycosidical aroma precursors in different extracting tea infusions were studied. The results showed the extract of glycosidical aroma precursor was promoted by using microwave and ultrasound.Studies on the filtration effect of green tea infusion showed that the membrane permeate flux decreased greatly at the early stage, and then varied gently. The analysis on the retaining rate of the main compounds by 0.2 m pore size ceramic membrane showed that the retaining rate of tea polyphenols, amino acid, caffeine was relatively low, while the retaining effect on the protein was apparent.更多还原