Department of Chemistry, Faculty of Science, University of Sistan and Baluchestan, P .O. Box 98135-674, Zahedan, Iran.
Department of Chemistry, Faculty of Science, University of Sistan and Baluchestan, P .O. Box 98135-674, Zahedan, Iran.
Food Chem. 2022 Sep 30;389:133082. doi: 10.1016/j.foodchem.2022.133082. Epub 2022 Apr 26.
Some factors such as oxidation can significantly affect the level of β-carotene after processing and during the storage of foods. Oxidative degradation of β-carotene with the active forms of oxygen produces β-carotene 5,6 and 5,8-epoxides. Two mechanisms involving a direct attack on the double bonds of the β-carotene by O (a neutral mechanism) and O (a radical mechanism) oxygen have been proposed and considered kinetically and thermodynamically by the density functional theory method. It concluded that due to the smaller energy barrier in the first step, the neutral mechanism with O is a more desirable path than the diradical mechanism with O and this was in complete agreement with the experimental reality of more reactivity of O. The energy barriers of the stepwise manner in the intersystem crossing pathway showed a more favorable pathway in the neutral mechanism. The deviation of spin contamination values was ignorable in the diradical mechanism.
一些因素，如氧化，会显著影响食物加工和储存过程中β-胡萝卜素的水平。β-胡萝卜素与活性氧形式的氧发生氧化降解，生成β-胡萝卜素 5,6 和 5,8-环氧化物。已经提出了两种涉及β-胡萝卜素双键被 O（中性机制）和 O（自由基机制）直接攻击的机制，并通过密度泛函理论方法进行了动力学和热力学考虑。结论是，由于第一步中的能量障碍较小，因此 O 的中性机制是比 O 的双自由基机制更可取的途径，这与 O 的更高反应性的实验事实完全一致。在体系间穿越途径中逐步方式的能量障碍在中性机制中显示出更有利的途径。自旋污染值的偏差在双自由基机制中可以忽略不计。
