Application of Advanced Oxidation Process as a Pre-Oxidation Step for Spent Lettuce Wash Water and for Decontaminating Fruit and Sliced Mushrooms

Wang, Hongran
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University of Guelph

Hydroxyl- and chloride-radicals exhibit high oxidant capacity that have found utility in treating wastewater in a process termed Advanced Oxidation Process (AOP). The following thesis developed, validated and verified radical treatments for treating spent wash water and for decontaminating fruit and mushrooms. Both treatments resulted in a >2 log CFU reduction of L. monocytogenes without negatively affecting mushroom quality or shelf-life. The optimized gas phase-chloride-radical treatment could effectively inactivate Salmonella, Escherichia coli O157:H7 and L. monocytogenes along with spoilage moulds. Finally, an AOP based process for reducing the chlorine demand of spent lettuce wash water was developed. The pre-oxidation treatment reduced the chlorine demand of water by 20 ppm and enhanced the stability of hypochlorite within the wash water. Collectively, the research has demonstrated the potential of hydroxyl- and chloride-radical processes to enhance the food safety and shelf-life of fresh produce and mushrooms.

Mushroom, Advanced Oxidation Process, Pre-oxidation, reduce chlorine demand, decontamination