The use of advanced oxidation processes in the degradation of the pesticide chlorpyrifos and reduction of microbial contamination on apples

A method based on Advanced Oxidation Process (AOP) was validated for the degradation of chlorpyrifos on apples and inactivating Escherichia coli O157:H7, along with Aspergillus niger spores. AOP generates free-radicals using UV-C light (at 254 nm), hydrogen peroxide, and ozone. The use of gaseous ozone alone was ineffective in chlorpyrifos degradation and was therefore excluded from AOP use. Response surface methodology (RSM) was used to find that the degradation of chlorpyrifos was primarily dependent on UV-C dose and hydrogen peroxide temperature but not hydrogen peroxide concentration. The maximal degradation of chlorpyrifos on apples was achieved through an AOP treatment applying 68.4 kJ/m2 UV dose and 1.22% v/v H2O2 at 66°C that resulted in a 47% reduction (92µg) of the pesticide with < 0.004 µg accumulation of chlorpyrifos-oxon. The same treatment supported a >6.56 log CFU reduction in E. coli O157:H7 and >6.56 log CFU reduction of A. niger spores. OMAFRA and agri-food innovation