| The differences of the contents of GABA and the activities of GAD among tea germplasms,the methods to increase GABA in tea,the quality characteristics of the GABA tea,the action of the GABA tea to mice depression and learning behaviour obstructed were studied in this research.Under natural condition,the average content of GABA of the tested tea germplasms was 0.09 mg/g,with the variation coefficient of 22.61%, the average activity of GAD was 1.57u/g,with the variation coefficient of 51.32%.After 3h anaerobic treatment, the average content of GABA of the tested tea germplasms increased to 1.29mg/g,with the variation coefficient of 27.60%, the average activity of GAD increased to 25.51u/g,with the variation coefficient of 21.83%.Based on the GAD activity of tea germplasms in natural condition the tested tea germplasms were divided into three groups.In the first group,they were small and medium tea germplasms with high GABA and GAD activity. In the second group,they were mainly medium and large tea germplasms. In the third group,they were mainly large tea germplasms with lower GABA and GAD activity.The GABA content of the tea made by the method of vacuum or immersion was higher than 1.50 mg/g,the standard content of GABA tea, while the GABA content of the tea made by the method of infrared ray or glacial acetic acid was lower than 1.50 mg/g.Treatment of the green tea with vacuum, the characteristics of GABA tea was implicated in the yellowish or reddish dry tea, the yellowish soup and the soaked leaves, the fragrance mixed with other odour, whereas the colour and the fragrance of the GABA tea made by immersion were similar to that of the control green tea, however, the taste of the soup of GABA tea was purer and thinner than that of the control green tea.The contents of the coffein and cyanidin of the GABA tea made by vacuum were close to that of the control green tea. Netherless,compared with the control green tea, the solid content of the water extract increased for 2.5%-6.1%, and the content of the free amino acids increased for 23.0%-39.1%, but the content of the tea polyphenol reduced 4.6%-11.6%. The contents of the coffein, tea polyphenol and cyaniding of the GABA tea made by immersion were close to that of the control green tea, and the content of the water extract reduced 2.5%-3.5%, the content of the cyaniding reduced 12.0%-14.6%, the content of the free amino acids increased 26.9%-54.5%.The relationship of GABA and Glu during the processing of GABA tea was shown as growth and decline. After treatment the green tea with vacuum, the content of GABA grew but that of Glu dropped. The content of GABA was further increased by the treatment that long time vacuum intervened by oxygen. After anaerobic treatment, the contents of Pro, GABA, Glygrew, while that of Glu, Asp dropped, and the contents of Thea, Arg, His changed little. From anaerobic condition to oxygen, the contents of GABA,Pro,Thr,Glu,Asp,Thea grew to varying degrees.The aromatic constituents of the tested tea were analyzed by GC-MS methods,64 aromatic constituents were identified. Cis-Jasmone, Neryl propionate and Cedrol were the characteristic constituents of the GABA teaâ… made by vacuum treatment, and for the GABA teaâ…¡made by immersion, they were Pentadecane,2,6, 0-trimethyl-, 3-Methylhexadecane.For the total amounts of the aromatic constituents, it was: GABA teaâ… > GABA teaâ…¡> control tea.The results of tail suspension and the forced swimming tests in mice,fed with the GABA tea for a long time,demonstrate that the GABA tea possessed significant antidepressant activities which might be attributed to the increasing GABA concentration of mice brain. Furthermore,the evaluation of scopolamine-induced learning and memory deficits of mice via step-down passive avoidance test suggested that the GABA tea could alleviate their symptom, which was not related to the changing of AChE acitivities.
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