Abstract
The measurement of stable isotope ratios of organic compounds in foods and drinks has been useful not only for the assurance of authenticity, the detection of adulteration and the inference of geological origin but also for clarification of relationship between metabolism of organism which produce metabolites and environments in which the organism grow. Tea is the most important beverage product in Japan, China, and some other Asian nations, because of the good taste and feeling relax when people drink. This is the effect of many amino acids in tea leaves and the special one of these is "theanine". Theanine is an amino acid which can originally be found in tea leaves. Except from this original source, it hardly found in any plants or just a small amount in only mushrooms. Therefore, isotope ratio of Theanine in tea leaves will potentially become unique indicator for environmental factors and/or metabolism in tea leaves. Here we developed the method for determination of isotope ratio of theanine in tea leaves. First we determined certified delta values of Theanine reagents purchased from several companies. Next we examined separation method of theanine by using HPLC.
