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The overall objectives are to study routes of introduction of hepatitis A virus (HAV) and E. coli O157:H7 into fresh produce at a pre-harvest level and develop control measures to reduce/eliminate HAV and E. coli O157:H7. Specifically, we will determine whether HAV and E. coli O157:H7 can localize at internal sites of spinach and green onions during growth. The persistence of HAV and growth and persistence of E. coli O157:H7 in spinach and green onions will also be determined. At the post-harvest level, the effect of high pressure and UV treatments on inactivation of HAV and E. coli O157:H7 in spinach and green onions and impact of those treatments on sensory quality will be determined. We expect to obtain a better understanding of routes of introduction of HAV and E. coli O157:H7 into spinach and green onions at the pre-harvest level and develop control measures to reduce/eliminate HAV and E. coli O157:H7. Results obtained from this study will be used to develop recommended commercial practices to produce processors and grower/packers and augment current GAPs, GMPs, and SSOPs recommendations.
NON-TECHNICAL SUMMARY: The microbial safety of fresh fruits and vegetables is of global concern. Several recent outbreaks of hepatitis A virus (HAV) associated with green onions and Escherichia coli O157:H7 with vegetables have heightened the concern with the safety of consumption of these foods. These outbreaks suggest data gaps exist at all levels from the farm to the consumer with respect to microbial safety of fresh and fresh-cut produce. Few or no studies have addressed the interaction of HAV and E. coli O157:H7 with growing spinach or green onion plants. At the post-harvest level, control measures for these two pathogens in spinach and green onion are either not available or not effective. In this proposed project, we intend to determine whether HAV and E. coli O157:H7 can localize at internal sites of spinach and green onions during growth through contact with contaminated irrigation water. At the post-harvest level, we would investigate the potential of using non-thermal processing technologies, high pressure and UV treatments, to destroy HAV and E. coli O157:H7 in green onions and spinach. We expect to obtain a better understanding of routes of introduction of HAV and E. coli O157:H7 into spinach and green onions at the pre-harvest level and develop control measures to reduce/eliminate HAV and E. coli O157:H7. Results obtained from this study will be used to develop recommended commercial practices to produce processors and grower/packers. This project will help to improve the safety of fresh and fresh-cut vegetables.
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APPROACH: To determine whether hepatitis A virus (HAV) and E. coli O157:H7 can become internalized in green onions and spinach through contaminated irrigation water, plants of green onions and spinach will be irrigated with water (spray or surface application) contaminated with E. coli O157:H7 or with HAV. On selected days of post-exposure, plants will be processed to determine numbers of E. coli O157:H7 or HAV. Real-time tracking of E. coli in plants during growth will be conducted. The ability of the target pathogens to persist and grow in the plants will also be determined. To evaluate the efficacy of high pressure and UV treatments on inactivation of HAV and E. coli O157:H7, green onions and spinach inoculated with HAV or E. coli O157:H7 will be subjected to high pressure or UV treatments. Experimental variables will include pressure level, treatment time and temperature for high pressure treatment and UV intensity, treatment time and temperature for UV treatment. The effect of mild heat, sanitizers, and acidic solutions in combination with high pressure or UV treatment on the inactivation of these two pathogens will also be investigated. Experiments will be statistically designed and data will be statistically analyzed. In education, Chen will include research findings from this project in his graduate-level course, Innovative Food Processing and Preservation Technologies. Students in this class will have the opportunity to conduct high pressure and UV experiments. Matthews will discuss the research findings in continuing education classes. Preserved sections of spinach and green onion tissue will be used in an undergraduate food microbiology laboratory course. Graduate students participating in the USDA fellowship program will have the opportunity to use the in vivo imaging system. This project will provide the opportunity for graduate students to develop a greater understanding of enteric foodborne pathogens and non-thermal processing technologies and work with specialized equipment. In extension, in order to reach targeted groups, the educational and outreach activities will focus on produce processors, regulators, and extension personnel. Several communication strategies will be used to cover the diverse nature of the targeted audiences, including printed materials, websites and other electronic media, videos, workshops, demonstrations, presentations, consumer and trade articles in periodicals, and press releases. All educational materials developed will be evaluated by focus groups and the four PDs. After one year of use, the materials will be re-evaluated by intended users to determine their relevance. Attendees of formal training programs will also have the opportunity to identify practices that they have changed as a result of the training and materials provided. The feedback will be used to improve the programs and to determine additional training needs. In research, we will publish results obtained from this study in peer-reviewed journals and present research findings at scientific meetings. Number of publications and presentations will be used to evaluate our research activities.