Study On The Changes Of Chromtic Values And Active Oxygen Metabolism In Green-making Process Of Oolong Tea

The changes of the chromatic values duing green-making was studied and 2 kinds of tea varieties were used as tested materials:Tie Guanyin and Mei Zhan.The trend was got:the value L* of Tie Guanyin was increased and Mei Zhan was decreased.The value a* of both varieties were increased. The value b* of Tie Guanyin was increased and Mei Zhan was decreased during green-making.The changes of the plamochromic pigments and their enzyme activities were determined during green-making.Tie Guanyin and Mei Zhan were used as tested materials.chlorophyll (Chl), carotenoid (Car) and lipoxygenase (LOX),chlorophyll enzymes (Chlase) and magnesium chelating enzyme (MDCase) were determined.The results showed that the plamochromic pigments and their related index of Tie Guanyin changes more gently,may be caused by the older and thicker of leaves,while Mei Zhan had the obvious change,through the correlation analysis,different tea varieties plamochromic pigments and the related enzymes had a certain correlation,but did not reach significant level.The changes of lipid peroxidation of chloroplast were determined,mainly includes:malondialdehyde (MDA),superoxide anion radical (O2-·),hydrogen peroxide (H2O2),etc.Tie Guanyin and Mei Zhan were used as tested materials.The results showeded that the lipid peroxidation level of Tie Guanyin chloroplast was relatively low,and the lipid peroxidation level of Mei Zhan was higher,B1 was higher than B2.Through the correlation analysis,the results showeded that the correlation of the plamochromic pigments and reactive oxygen species was higher in different tea varieties,and the indexes of lipid peroxidation in chloroplast was higher,too.The changes of active oxygen metabolism were determined,which mainly included:superoxide dismutase (SOD),peroxidase (POD),polyphenol oxidase (PPO) and tea polyphenols (TP),etc.Tie Guanyin and Mei Zhan were used as tested materials.The results showed that the indexes in the reactive oxygen removal systems of A1 had no significant correlation,and the indexes in reactive oxygen removal system of A2 had a significant correlation,various factors may account for the indexes in active oxygen removal system of B1 and B2 which had a certain degree of correlation. Through correlation analysis,the plamochromic pigments of A1 and TP were significantly negative correlation,but no significant correlation between the indexes and plastid pigments of A2.The plamochromic pigments of B1 and TP was significantly positively related,the same as B2,but which did not reach significant level.The changes of the AsA-GSH cycle were determined,mainly includes:reduced ascorbic acid (AsA) and reduced glutathione (GSH),ascorbic acid peroxidase (APX) and glutathione reductase (GR),etc.Tie Guanyin and Mei Zhan were used as tested materials.The results showeded that the AsA-GSH cycle had certain relevance in different varieties of tea and processing.The removal of the H2O2 had more to do with the AsA-GSH cycle while the removal of the H2O2 had more to dowith the POD-H2O2 decomposition system in further analysis.At the same time,the plamochromic pigments had significant correlation with the nonenzymatic antioxidants in the AsA-GSH cycle,indirectly showeded the correlation of the plamochromic pigments and reactive oxygen species.