State Key Laboratory of Food Science and Technology , Jiangnan University , Wuxi , 214122 , China.
International Joint Laboratory on Food Safety , Jiangnan University , Wuxi , 214122 , China.
J Agric Food Chem. 2019 Jan 30;67(4):1254-1260. doi: 10.1021/acs.jafc.8b05146. Epub 2019 Jan 22.
The effects of catechins on N-(carboxymethyl)lysine (CML) and N-(carboxyethyl)lysine (CEL) formation in green tea and related model systems were investigated in this study. Since the first step of green tea processing entails enzyme inactivation, the catechin content was maintained at a high level during processing. However, drying still had a great effect on CML and CEL formation, while other steps also contributed. Hence, model systems were developed to analyze the effects of catechins on CML and CEL formation. Catechins ((-)-epicatechin gallate, (-)-epigallocatechin, and (-)-epigallocatechin gallate) could inhibit CML formation in the model imitating the condition of green tea processing, though the inhibitory efficiency was reduced by transition metals. This suggested that catechins could inhibit CML formation in the real tea system, though the inhibitory efficiency may be reduced by tea components which promote its synthesis. However, CEL formation was not always inhibited by the tested catechins, though catechins could significantly decrease the content of methylglyoxal which is considered an important intermediate. Consequently, the main pathway of CEL formation may not be through methylglyoxal.
本研究探讨了儿茶素对绿茶及相关模型体系中 N-(羧甲基)赖氨酸 (CML) 和 N-(羧乙基)赖氨酸 (CEL) 形成的影响。由于绿茶加工的第一步是酶失活，儿茶素含量在加工过程中保持在较高水平。然而，干燥对 CML 和 CEL 的形成仍有很大影响，而其他步骤也有一定贡献。因此，建立了模型体系来分析儿茶素对 CML 和 CEL 形成的影响。儿茶素（(-)-表没食子儿茶素没食子酸酯、(-)-表儿茶素、和 (-)-表没食子儿茶素没食子酸酯）可以抑制模型中模仿绿茶加工条件下的 CML 形成，尽管过渡金属会降低抑制效率。这表明儿茶素可以抑制真实茶体系中的 CML 形成，尽管其抑制效率可能会被促进其合成的茶成分降低。然而，测试的儿茶素并不总是抑制 CEL 的形成，尽管儿茶素可以显著降低被认为是重要中间产物的甲基乙二醛的含量。因此，CEL 形成的主要途径可能不是通过甲基乙二醛。
