Theoretical study on the mechanism and kinetics of the formation β-carotene epoxides from the oxidative degradation of β-carotene

Abstract

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 ¹O₂ (a neutral mechanism) and ³O₂ (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 ¹O₂ is a more desirable path than the diradical mechanism with ³O₂ and this was in complete agreement with the experimental reality of more reactivity of ¹O₂. 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.

Keywords: Activated oxygen; DFT method; Mechanism; β-Carotene; β-Carotene epoxide.