The Research On The Premium Processing Procedures Of Instant Green Tea And The Variation Of Its Functional Component

This thesis introduced the basic concept, processing principle and procedures of instant tea, based on the previous experiment data, researched the main factors during the processing procedure. Combined with experiment and analysis, find the key factors that affect the quality of instant green tea, and confirmed the best processing procedures for industry production.The processing procedure is as below:Counter flow extraction→squeezing machine→centrifugation→Ceramic membrane separation→reverse osmosis→Centrifugal membrane evaporation→Spray drying.This experiment researched the key point affecting the quality of instant tea during the production, discussing their relation with instant tea quality. The main conclusion is as below.1. The extraction temperature, time, tea/water ratio has significant impact on the tea powder quality. The premium condition is confirmed as:80℃temperature, extract time 80mins, tea leave/water ratio 1:20, under such circumstances, the functional component in tea leaves can be extracted maximally. The recovery rate of dry powder can reach 25.13%.2. In the procedure of membrane concentration, when the working pressure of reaches 1.2MPa, the time of filtration is shortest, and the macro molecular can be removed and there won't be "tea cream" problem, Also this is reduce the oxidation of EGCG, Adopting the low temperature during the filtration process can also reduce the oxidation of EGCG.3. The reverse osmosis concentration has better production capacity and lower temperature. The main functional component content in tea liquor is relatively stable.4. There are four factors affecting the centrifugation concentration. The influence of four factors are temperature> vacuum degree> flow-in volume> timeThe best condition for centrifugation membrane is 48℃,vacuum degree 0.086MPa, the variation of TP content is minimum. The flow-in volume and the concentration time do not have significant influence on the tea polyphenol content.5. For the two spray drying method, the steam pressure do not have much influence on the tea polyphenol content, however, the temperature has significant influence on the tea polyphenol content. During the processing procedure, the temperature should be strictly controlled, the temperature for centrifugation spray drying is 205℃, the pressure spray drying is 180℃. When the temperature is stable, the steam pressure can be reduced in order to improve the economic returns.6. The TP, EGCG, CAF content are decreasing during the processing procedure, the key point are the extraction, membrane filtration and drying. Those three procedures contribute 90% of the losing rate. Therefore suitable processing parameters should be adopted for the three key point in order to guarantee the quality.