Innovative Technologies for Sanitizing and Preserving Locally Grown Produce

NON-TECHNICAL SUMMARY: Fruits and vegetables are susceptible to natural contamination from soil, insects, birds, water, and other sources during growth and harvest. Although most environmental microbes found on raw produce are considered benign, contamination with spoilage microorganisms and human pathogens presents a persistent challenge to the fresh produce industry. Inadequate produce packing, processing, or sanitation can result in further spread of undesirable microorganisms, leading to serious cross-contamination, product damage and/or foodbrone illness outbreaks. Contaminated produce items have caused several large outbreaks of human salmonellosis over the past few years. These outbreaks and related investigation reports suggest persistent field contamination. Further efforts are needed to prevent and reduce produce contamination on farms and throughout the food supply chain. Some produce sanitizing technologies (such as treatments with ozone, chlorine dioxide, bacteriophage, etc.) have been developed recently with claims of effective pathogen reduction. Additional research is needed, however, to validate and/or enhance the efficacy of these technologies to assure produce food safety.

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APPROACH: Objective One: To development and validate produce sanitizing techniques for small-scale produce packing and food service operations Raw produce (tomatoes, green onions, melons, edamame, etc.) from packing facilities or grocery stores will be inoculated with multiple strains of human and plant pathogens such as Salmonella enterica and Erwinia carotovora to simulate serious field or postharvest contamination. Subsequently the inoculated produce will be washed and sanitized using water containing chlorine dioxide, ozone, organic acids, and/or bacteriophages. Washing systems with and without brushes will be established with various operation time, flow-rate, and agitation or brushing speed. The efficacy of these treatments (applied independently or in combinations) toward pathogen reduction will be measured using selective agar plating and Enzyme Linked Immunosorbent Assay (ELISA). Furthermore, Transmission and Scanning Electron Microscopy will be used to aid interpreting findings of impacts of washing on the removal of pathogens from produce tissues . <P>
Objective Two: To development and challenge produce preservation techniques for small-scale produce processing and food preparation Raw produce (tomatoes, green onions, melons, edamame, etc.) from packing facilities or grocery stores will be inoculated with multiple strains of human pathogens such as Salmonella enterica and Escherichia coli to simulate serious field or postharvest contamination. Subsequently the inoculated produce will be sanitized using the methods developed in Objective one and/or dehydrated using an environmental chamber with and without the addition of various preservatives or antimicrobial substances (such as bacteriocins, bacteriophages, etc.) applied either independently or in combinations. The survival and growth of the inoculated pathogens during the process of preservation and product storage with and without refrigeration will be monitored for up to 6 months using selective agar plating and Enzyme Linked Immunological Assay. Surviving strains may be analyzed using Pulsed Field Gel Electrophoresis to understand the influence of contaminant variation (bacterial strains) on the microbial safety and quality of preserved produce items.