Abstract: Microwave-assisted extraction of green tea showed certain effect on catechins yield rate and composition of catechins, however, it lack of systematic research. Based on systemic investigation on the influence of extracting power, extracting time, ratio of tea and water, water temperature and extracting times of microwave-assisted extraction on the composition and yield rate, the test processing parameters with the least influence of microwave extraction and higher yield rate on the composition were optimized and screened, which provide the reference for application in the industrialization of microwave-assisted extraction on tea by using the green tea as the raw material and the composition and yield rate in the extraction as the major index and used the industrial water as the control and the orthogonal test as the method of verification. Under the above mentioned parameters, the microwave-assisted extraction of green tea showed the least influence. The results showed that the optimum parameters were obtained at the ratio of solid to liquid of 1﹕25, microwave-assisted extracting power of 539W, microwave extracting time of 2min, extracting water temperature of 90℃, and the two times of extracting. The rate of EGC﹕DL-C﹕EC﹕EGCG﹕GCG﹕ECG was 3.25﹕0.12﹕1.00﹕7.66﹕0.49﹕1.82,the yield rate of the individual catechins was 130.47%、22.98%、124.62%、114.40%、7.39%、96.64% of yield rate extracted by industrial water. Compared with the current industrial technology, this method showed better practicability and results for the extraction of tea polyphenol and catechins.

Key words: green tea, catechin, microwave technology, extraction