| In recent years, the freeze concentration technology is often seen in research reports. In China, the freeze concentration technology has been applied to wine, juice, medicine and other industries, and in the tea has just begun. The paper conducted the basic study on the freeze concentration in green tea drink systematically and comprehensively. Firstly, we explored the laws of freeze concentration of green tea initially by examining the effect of concentraion factors such as concentration of green tea drink, freezing temperature, stirring speed. Secondly, we studied the effect on the main chemical components of tea in the continuous freeze concentration and established a mathematical model for simulation. Finally, freeze concentration was compared with other concentrations, to verify the the feasibility of the application of that in green tea. In this study, under the test apparatus and test conditions, the results obtained are as follows:Through the equipment of freeze concentration by our designed and developed, we determined the freezing temperature of concentration of 1-20°Brix of green tea, and mapped out the curve about crystallization of different concentrations of tea. Through the study on the impact of factors on the concentration effect, the results showed that tea made of the proper pre-cooling, choose the temperature near the freezing point as the freezing temperature, stirring speed is high, the ice crystals of high purity, concentration effect is the best.A continuous of freeze concentration of green tea was conducted. The trend of the main chemical compounds before and after freeze concentration was studied. The result showed that, in the frist concentration, the changes of the main chemical compounds are small, low to 10%. The changes of the main chemical composition in second concentration are more than the first concentration. Catechin components in the process of concentration, the smallest change is EC, followed by EGC, C, ECG and EGCG, the changes of simple catechins is more than ester catechins.Freezing time and quality of the concentrate and ice crystals were built to a mathematical model. We estimated the model parameters and simulated the model by using the Runge - Kutta method in the computer. In the final simulation results, R 2 reached 0.9613 in the first concentration, R 2 is 0.9458 in the second concentration, indicating that simulated results and experimental curves are described basically the same, there is a high degree of fitting.The freeze concentration was compared with rotary evaporation concentration and the membrane concentration. From the quality point of view, after treatment by the frozen concentrated tea, basically maintaining the original flavor of the former concentration, the quality is very stable. Tea by the membrane concentration treatment, although the aroma and the taste is slightly lower with frozen concentrated sample, but also largely retain their original flavor. Concentrated by rotary evaporation, the aroma and taste of tea is larger change. The retention rate of solid contents in rotary evaporation concentration is best, followed by membrane concentration, finally the freeze concentraion. There is no significant changes in the chemical composition after freeze concentration treatment. After membrane concentration treatment, polyphenols, amino acids, catechins increase, but caffeine reduced by nearly 25%. In addition to sugar, the contents of other chemical components were reduced by 15% to 25% in rotary evaporation treatment, the effective material significant loss. At room temperature, membrane concentration of the lowest energy consumption, freeze concentration was slightly higher than rotrary evaporation.
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