Colouration of Toki-shakuyaku-san extract granules and the production of high-molecular compounds under heat-stress storages

We previously suggested that the colouration (browning) of Toki-shaku-yaku-san extract granules (TJ-23) was related to the Maillard reaction under heat-stress storage. In this study, we investigate the production of browning high-molecular compounds and discuss the relationships among the respective contents of these compounds, amino acids and reducing sugars and the colouration (Delta E*(ab)) of TJ-23 under heat-stress conditions. As a result of the investigation, it was found that peaks corresponding to the high-molecular compounds were separated from the heat-stressed samples of TJ-23 at each molecular weight of about 5000, 10000, 230000 and 3000000, and especially the latter two peaks increased in areas up to about 11 times and 4 times at 60 degrees C from 10 through 90 d respectively. At the same time, it was confirmed that the contents of amino acids and reducing sugars decreased with an increase in storage temperature at 10 d. Furthermore, it has become apparent that the content of high molecular compounds was correlated with colour differences (Delta E*(ab)) of heat-stressed TJ-23, and then those compounds were related to the decreases of glucose and amino acids. From these results, we confirmed that the browning of Kampo medicines extract granules might proceed partially by Maillard reaction under higher temperature and/or longer time conditions.