Degradation of citrinin by different types of light and hydrogen peroxide

Citrinin (CIT), a mycotoxin produced by Monascus, Penicillium, and other fungies, can contaminate red yeast rice and other foods, thus constraining their application and development. Exploring efficient degradation methods of citrinin is becoming as one of the hot research topics. In this study, the degradation of citrinin, irradiated by visible (Vis) light, ultraviolet (UV) light, and simulated sunlight alone, as well as in combination with hydrogen peroxide (light/H2O2), was investigated. The research demonstrates UV, Vis, and simulated sunlight all have a degree of degradation on citrinin, and the degradation efficiency correlates with light source and light intensity. Interestingly, when combined with 100 W Vis and 0.01 M H2O2, the citrinin degradation rate increases to 32%, compared to 1% and 5% achieved by Vis and H2O2 alone. Hydroxyl radicals, arising from the uniform cracking of H2O2 under Vis, were experimentally validated by electron spin resonance measurement and could accelerate the dissociation of citrinin by nucleophilic attacking. Employing the density functional theory, we deduced nucleophilic center dot OH mainly attack onto C-8 and C-5 site by comparing the electrophilic Parr functions (Pk(+)) value of main C atom of citrinin. This research presents a rapid and efficient degradation of citrinin by combining visible light with H2O2.