Iranian Academic Center for Education, Culture and Research (ACECR) - Iranian Institute of Research and Development in Chemical Industries. Enghelab Street, Fakhre Razi street, Shohadaye Jandarmeriye Sharghi, No. 172, 3rd Floor, Tehran, P.O. Box 13145-1494, Iran.
Food Sci Technol Int. 2010 Dec;16(6):505-10. doi: 10.1177/1082013210367567.
The effects of temperature (50, 60, 70, 80, 90 °C) and time (5, 10, 20, 40, 80 min) on catechins and caffeine solubility in water from Iranian green tea were investigated, The best combinations of temperature and time extraction with water were 20-40 min, 80 °C for epigallocatechin (EGC), epicatechin (EC) and caffeine (Caff), and 80 min, 90 °C for catechin (C), epicatechin gallate (ECG) and epigallocatechin gallate (EGCG). A mathematical model derived from Fick's second law was then used to calculate the diffusivity of the components, and to monitor the effect of temperature on the diffusivities. The extraction of these components is governed by two diffusion processes: fast and slow. The results showed that the intra-particle diffusion was the rate-governing step of the extraction process. The slow stage diffusivities of these components at their optimum extraction temperatures were calculated as: 1.94e-9 (EGC), 8.1e-10 (EC), 3.9e-10 (Caff), 1.34e-8 (C), 4.2e-9 (ECG) and 4.63e-9 (EGCG).
研究了温度（50、60、70、80、90°C）和时间（5、10、20、40、80 分钟）对伊朗绿茶中儿茶素和咖啡因在水中溶解度的影响。用热水提取儿茶素和咖啡因的最佳温度和时间组合分别为 20-40 分钟、80°C（表没食子儿茶素（EGC）、表儿茶素（EC）和咖啡因（Caff））和 80 分钟、90°C（表儿茶素（C）、表儿茶素没食子酸酯（ECG）和表没食子儿茶素没食子酸酯（EGCG））。然后，使用从菲克第二定律导出的数学模型来计算各组分的扩散系数，并监测温度对扩散系数的影响。这些成分的提取由两个扩散过程控制：快速和缓慢。结果表明，内扩散是提取过程的速率控制步骤。在最佳提取温度下，这些成分的慢扩散系数计算为：1.94e-9（EGC）、8.1e-10（EC）、3.9e-10（Caff）、1.34e-8（C）、4.2e-9（ECG）和 4.63e-9（EGCG）。
