Study On The Catalysis Of Immobilized Enzymes On Green Tea Drink To Improve Aroma Quality

Pectinase , p-glucosidase and the acetone powder containing crude enzymes made from cv Yunnandayezhong cv Shuigu and cv Fudingdabai were put into brews of five varieties of tea plants in order to improve the brews quality.Overall, enzymes obtained from the fresh tea leaves of three cultivars had significant effects on the liberation of aromas. The immobilized enzyme from cv Yunnandayezhong had the highest effect on the liberation of aroma among the three tested enzymes. The total amount of aromas liberated by the catalysis of enzyme from cv Yunnandayezhong on Maoxie increased by 30 times. Tea samples processed from Maoxie and Zhenong 25 liberated more aromas under the catalysis of each tested enzyme, which suggested that those two tea samples might contain more aromatic precursors.After hydrolysis catalyzed by P-glucosidase, the aromas increased in different degrees in tea samples processed from five cultivars .For the effect of pectinase on the changes of aromas of tea infusion, aromas of the five tested tea infusions were increased in different degrees except tea from cv Zhenong 25. The organoleptical taste of tea drinking showed that the aroma and quality of green tea drinking could be improved by adding into pectinase tea infusion and tea drinking was stored more long.The total peak areas and the amount of alcoholic aromas in teainfusion were higher in the treatment of adding mixed enzymes (Pectinase and Yunnandayezhong enzyme) than those of adding each of individual enzymes. Although the total peak areas of aromas of treatment of mixed enzymes on Maoxie tea was the highest among the group, the organoleptical tasting showed that this treatment was not the best one, which indicated that the ratio rate of alcoholic aromas to the total aromas may be very important to quality of tea infusion. It was found that a better organoleptical taste of aroma could be obtained while the ratio rate of alcoholic aromas to the total aromas ranged at 46% to 60%. The results of the effect of adding enzyme into tea infusion on the organoleptical taste of tea drinking showed that the kinds of aroma and quality of green tea drinking could be improved by adding enzyme into tea infusion. The treatment of the mixed enzyme on tea processed from Zhenong 25 liberated a relatively more pleasant smell and aroma. Pectinase on tea processed from Maoxie, an improved smell and aroma was obtained.There were some changes of catechins happened in tea infusions after immobilized enzyme being added, the content of epicatechins such as GCG, ECG, and CG changed much more than those non- epicatechins except C, EGC degraded much more than other components of catechins.