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Microbial food safety of raw or minimally processed fresh produce is a significant challenge. The current sanitation processes are effective for inactivation of bacteria in wash water but have limited efficacy (less than 2 log/g reduction) for inactivation of microbes on the surface of fresh produce. This study demonstrates a novel concept to enhance effectiveness of chlorine using a particle based sanitizer to improve decontamination of fresh produce. In this concept, enhanced effectiveness is achieved by localized high concentration of chlorine bound to the surface of silica particles and improved surface contact of microparticles with the produce surface using mechanical shear during a washing process. The results of this study demonstrate that 500 ppm of active chlorine can be bound to the surface of modified silica particles. These modified particles maintain over 90% of their initial chlorine content during extended storage in aqueous solution and provide improved inactivation of both E. coli O157:H7, L. innocua and P. fluorescens in the presence of organic content in contrast to conventional chlorine sanitizer. The modified particles exhibit an effective sanitation efficacy of fresh produce (more than 5 log reduction) in the presence of relatively high organic content (chemical oxygen demand of 500 mg/L), demonstrating a potential to address a significant unmet need to improve fresh produce sanitation. The particle based sanitizer had no significant effect on the quality of fresh lettuce. Importance: The limitation of current sanitation processes for inactivation of microbes on the surface of fresh produce is due to non-specific consumption of sanitizers by reactions with the food matrix and complexity of surface chemistries and structural features of produce surface. This study demonstrates a novel approach to enhance sanitation effectiveness of fresh produce using a particle based sanitizer. The particle based sanitizer concept provides localized high concentration delivery of chlorine to the surface of fresh produce and enables more than 5 logs of inactivation of inoculated bacteria on fresh produce surface without significant changes in produce quality. The results of this study illustrate the potential of this approach to address the unmet need for improving sanitation of fresh produce. Further validation of this approach using a scaled up produce washing system will enable commercialization of this novel concept.
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