Study on variation of physicochemical indexes and tea quality during scented processes of jasmine tea

To improve the standardization level in jasmine tea production and keep its' quality stabilized and governed, this paper studied the temperature variety regulation of “flowers, leave, and piles”, which called the three elements in essay, and eventually proven the variations on physical and chemical compositions in the course of jasmine tea scenting stages. The research indicated that :the temperatures varied following “lowhigh-low-medium” tendency in the scented processes. The flower temperature (43.6℃) presented significant higher (p<0.05) comparing to leaf (42.04℃) and pile (42.24℃) temperature, which average temperature rate was at 0.63℃/h, and the average moisture content of flowers (84.78%) presented higher than that of leaves (5.25%) . The temperature and moisture differences formed the motive power of tea absorption from flowers. By analyzing the quality of sensory and chemical in scented processes, it could be concluded that :the water extract, tea polyphenols, caffeine and flavonoids content of tea appearing reduced significantly (p<0.01) . And tea polyphenols content presented reduced significantly ( p <0.05) . However, amino acid content presented increase significantly (p<0.01) , which was from 2.69% to 3.25%, the flavor of tea changed from fired bean to strong jasmine smell, and the taste changed from bitter to heavy and mellow.