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<OL> <LI> To evaluate the impact of fresh-cut preparation practices on metabolic processes of fruits and vegetables, microbial survival/growth, and their interactions. <LI>To understand survival strategies used by human pathogens on fresh-cut produce. <LI>To develop postharvest intervention strategies to limit growth of human pathogens on produce.
Approach:
To detetermine the effect of industry fresh-cut practices on produce metabolism, we will focus on the washing/sanitizing process since it is a critical control point for HACCP food safety programs. Produce tissue damage, wound response and sensory quality of fresh-cuts prepared using various conditions will be evaluated during storage. Adherence assays for relevant Enterohemorrhagic E. coli have already been developed to study the attachment to lettuce surfaces. Microscopy will be used to examine bacterial adherence patterns using GFP-expressing strains to determine if these adherence patterns suggest particular pathogen reduction schemes. Using gene array analyses, we will identify the gene circuitry involved in attachment-mediated acid tolerance and compare gene expression patterns among attachment-defective S. typhimurium and E. coli mutant strains. Optimization of phage delivery systems, in combination with other factors such as bacteriocins, will be examined for its efficacy to control foodborne pathogens on produce.