| Oolong tea is a unique type of famous tea in China, which is known as its special aroma like flowers and fruits, taste of briskness and mellowness. In recent years, many researches show that oolong tea has physiological and pharmacological functions of reducing blood pressure, fat and cholesterol, anti- radiation and anti-senescence. So that more and more people take drinking oolong tea every day as a good way to become slim and healthy. These trends accelerate consumptions and demands of oolong tea. Based on these matters, deepening studies on mechanism of character formation of oolong tea become more important now, and these researches will help us to expand production area and optimize technis of oolong tea for further quality improvement and higher grade ratio of oolong tea productions. From year 1987 to 1993, after a series of repeated trials, professor Yang wei-li with her co-workers instituted new technics of oolong tea, which was available of using local tea varieties of Hunan province to process oolong tea. Compared with traditional technics of oolong tea, new technis saves 1/2 -2/3 ratio of time during rotation state, which includes 3 times of shaking procedures and spends about 6 hours.Rotation technics, spelled as Zuo-qing in Chinese, is the key procedure in processing of oolong tea, and plays a very important role in aroma and taste formation of oolong tea. Rotation technics includes withering and shaking procedures, spelled as Shai-qing and Yao-qing in Chinese respectively. In this research, two varieties of tea tree named Meizhan and Maoxie were selected, and fresh tea leaves be treated with new technics of oolong tea. Besides, two contrasts were arranged, namely, after fresh tea leaves withered under sunlight for 15-30 minutes, took some tea leaves treated with no shaking operation and made this as contrast No.1(CK1). When finished shaking procedures of new technics, which includes 3 times of shaking operation, taking some tea leaves to be shook 2 times sequentially and make that as contrast No.2 (CK2). Then studied dynamic variation of endogenous Cellulase (CE) & Polygalacturonase (PG) activity and major biochemical components of being processed tea leaves during 3 treatments above-mentioned. Trials results will be summarized as follows:After withering procedure, the CE activity increases rapidly, and keeps on increasing until reaches the peak value at finish of 1st shaking. But in the state after 1st shaking, includes the 2nd, 3rd, 4th shaking, CE activity declines gradually. CE activity and its change breadth of CK1 are low than those of new technis, but variation trends of CE activity in these two treatments keepunanimous. There has obvious variance of CE activity among whole leaf, leaf-edge and leaf-center, but they keep the same variation trends of activity. At the 1st and 5th shaking course, there has greater variance of CE activity among whole leaf, leaf-center and leaf-edge. CE activity finishes its activation during shaking procedure of new technics. Statistical analysis shows that there has significant variance of CE activity in different tea varieties (p<0.05). CE activity of Meizhan variety is low than that of Maoxie variety. Besides, multiple comparisons reveal that there are significant variances of CE activity among various shaking procedure (p<0.05), CE activity of 1st shaking has significant variance with that of freshness, the 2nd, 3rd and 4th shaking. The variation of containing water in tea leaves during rotating course has significant positive linear relationship (p<0.05) with CE activity.PG activity rises slowly after withering procedure, and keeps rising as a whole until reaches the peak value when the 3rd shaking finished. But in the state of continuing shaking based on new technics, its activity declines with big breadth gradually. PG activity of CKi is low than that of new technis, but variation trends of PG activity in this two treatments keep unanimous. There also has obvious differentiation of CE activity between leaf-edge and leaf-center, but they hav... |
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