Chen, Pengyu2022-01-172022-01-172022-01-16vt_gsexam:33825http://hdl.handle.net/10919/107688Fresh produce may be contaminated by bacterial pathogens including Listeria monocytogenes during harvesting, packaging, or transporting. Consumers may be at risk of foodborne illness if produce become contaminated. In this project, a cavitation process (formation of bubbles in water) was studied to determine the efficacy of microbubbles at inactivating the pathogen L. monocytogenes on stainless steel and the surface of fresh cucumber and avocado. Stainless steel coupons (1"×2''), cucumber, and avocado surfaces were inoculated with L. monocytogenes (LCDC strain). After 1, 24 or 48 h, loosely attached cells were washed off, and inoculated areas were targeted by microbubbles (~0.5 mm dia.) through an air stone (1.0 L air/min) for 1, 2, 5, or 10 min. After treatment, samples were transferred to sterile containers and serial diluted in peptone water and plated on Oxford agar. Plates were incubated for 48 h at 35℃. For stainless steel, the mean log reduction of L. monocytogenes (48 h drying) peaked at 2.95 after 10 min of microbubbles when compared to a no bubble treatment. After 48 h pathogen drying, cucumbers treated for 10 min resulted in a 1.78 mean log reduction of L. monocytogenes. For avocados, the mean log reduction of L. monocytogenes (24 hr drying) peaked at 1.65 after 10 min of microbubbles. This cavitation treatment (10 mins) reduced over 95% of L. monocytogenes on the surface of stainless steel, cucumber, and avocado. Microbubble applications may be an effective, economical, and environmental-friendly way to remove L. monocytogenes and possibly other bacterial pathogens from food impact surfaces and the surface of whole, intact fresh produce.ETDenIn CopyrightFoodborne illnessListeria monocytogenesListeriosisStainless steelCucumberAvocadoCavitation bubblesCross-contaminationThesis