Identification of degradation pathways and products of cyanidin-3-sophoroside exposed to pulsed electric field

Abstract

Pulsed electric field (PEF) can induce the degradation of anthocyanins. In this study, the degradation products and postulated degradation mechanism and pathways of cyanidin-3-sophoroside (Cy-3-soph) by PEF were investigated using a combination of UV–vis spectra and HPLC-MS. Four isomers of quinonoid benzoyloxyphenylacetic acid esters resulting from the oxidative degradation of Cy-3-soph at pH 1.5 and 3.5 were detected in a model solution after PEF. The prevailing degradation pathway was different from thermal degradation. Cy-3-soph was degraded through a Baeyer–Villiger oxidation by the nucleophilic attack of hydrogen peroxide and then further oxidised by other oxidants, such as the hydroxyl free radical induced by the electrochemical reactions during PEF treatment. The thermal degradation pathways at pH 1.5 and 3.5 were also involved in the degradation of Cy-3-soph during PEF treatment.