期刊
JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
卷 54, 期 16, 页码 5924-5932出版社
AMER CHEMICAL SOC
DOI: 10.1021/jf0611419
关键词
tea catechins; thermal stability; epimerization; degradation; kinetic model
Tea catechins may undergo complex reactions such as oxidation, polymerization, and epimerization during thermal processing. The thermal stability of tea catechins in an aqueous system, including degradation and epimerization reactions, was investigated using a microwave reactor. Reactions were controlled at high temperatures ranging from 100 to 165 C with various durations up to 120 min. Three sources of tea catechins containing different levels of (-)-epigallocatechin gallate ( EGCG), (-)- epicatechin gallate ( ECG), and their epimers were studied. Kinetic models for the degradation/epimerization of tea catechins were developed and validated by the reactions at 145 C. It was shown that the epimerization and degradation of tea catechins followed first-order reactions and the rate constants of reaction kinetics followed the Arrhenius equation. Values of the activation energy ( E a) for the epimerization of EGCG from epi-to nonepi-structures, the epimerization of GCG from nonepito epi-structures, and the total degradation of EGCG and its epimer GCG were 117.6, 84.2, and 42.8 kJ/mol, respectively. For ECG and CG, the E a values were 119.3, 96.2, and 41.6 kJ/mol, respectively. The mathematical models may provide a useful prediction for the loss of tea catechins during any thermal processing.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据