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Theanine tea unique non-protein amino acids, generally accounting for tea dry weight of 1% to 2%, a large proportion of free amino acids, its content was positively correlated with the quality of the tea, the tea taste important flavor substances. In recent years, theanine research focuses on the physiological action, biochemistry, pharmacology, and health functions. L-theanine as a safe, non-toxic, natural food additives with a variety of physiological functions, and has broad prospects for development. The study found the dry tea in addition to L-theanine, there is a small amount of D-theanine exist. D-Theanine also has a sweet taste and L-theanine. Although theanine enantiomer of absolute content with the kind and quality of tea is not relevant, but with the origin of different grades of tea theanine enantiomer ratio is very different enantiomeric analysis study may be divided as tea level tools. Therefore, it is necessary to study the change of theanine in the different teas. This is the first system to study the changes of theanine in green tea, Pu'er tea and oolong tea, and follows with innovative research results: 1, accelerated shelf life test methods Roasted Green Tea Tea ammonia under different storage conditions acid changes. Experimental factors and levels were: the tea water content 3.98%, 5.03%, 6.10%, oxygen partial pressure control 2%, 10%, 20%, respectively, placed as 5 ° C and 15 ° C, 25 ° C, 35 ° C storage temperature for a period of 6 months storage, sampling once every 60 days by the chiral derivatization high performance liquid chromatography determination of L-theanine in tea samples and D-theanine content. The results show that: the tea water content, oxygen component, storage temperature and storage time four factors, the oxygen component of the sample L-theanine is not significant, other factors were significantly affected. During storage, in the storage interim 120d when the L-theanine content increased significantly, and after the downward trend. Detected after 180d storage, sample D-theanine content of as 1mg/100g to 2.1mg/100g, respectively, accounting for 0.09% to 0.16% of the total theanine Roasted Green Tea is a high temperature in a long time stored under the conditions to produce D-theanine. 2, the analysis showed that the five different production areas in Yunnan Pu'er tea raw tea and cooked tea theanine: L-theanine Pu'er cooked tea of ??15 samples in the range of 20mg/100g ~ 104mg/100g each production interval no apparent regularity trend; 15 cooked Pu'er tea were not detected in the D-theanine. 15 Pu'er tea, L-theanine content the 628mg/100g-2131mg/100g within each sample L-theanine significant difference, but each production interval no apparent regularity changes trend. The raw tea L-theanine content is much higher than the cooked tea. Pu'er tea is only detected in the samples H2 D-theanine content 4.3mg/100g. Theanine analysis of seven different varieties and processing of oolong: Pu'er tea and green tea, L-theanine and D-theanine detected in 7 oolong tea samples. L-theanine content of 10 mg/100g respectively 371mg/100g, D-theanine content of 6 mg/100g respectively to 18mg/100g accounting for the total amount of 1.94% to 66.16% of the theanine, D-theanine which Honey Orchid oolong tea up 66.16%. D-theanine Luzhou-flavor oolong tea significantly higher proportion of Fen oolong tea. This indicates that the thermal processing of oolong tea after a long, L-theanine happened racemization, high re-roasted Luzhou-flavor oolong D-theanine. 4, the research on tea and oolong tea, green tea during storage theanine enantiomer analysis, indicating that green tea for a long time storage will produce theanine racemization processing of Oolong tea theanine racemization, theanine enantiomer content can be used as indicators of green tea the storage, oolong quality, etc., to provide the test data and the basis for theanine in tea quality control.
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