1a. Objectives (from AD-416):
To determine sensory, nutritional and/or product quality impacts of efficacious food processing interventions and combinations of interventions. To develop antimicrobial packaging-based treatments for controlling pathogens. To identify compounds of potential concern formed by novel non-thermal food processing interventions. To develop/optimize treatment processes and combinations to control pathogens and to minimize loss of product quality and value.
1b. Approach (from AD-416):
An integrated approach to enhance microbial safety while maintaining product quality will be adopted by combining efficacious treatments and processes with antimicrobial packaging. Current antimicrobial treatments, processes, and intervention technologies that have been demonstrated to be effective in inactivating human pathogens will be modified and evaluated to confirm their effectiveness in obtaining a minimum 3 log CFU/g reduction of E. coli O157:H7 and Salmonella spp. on fresh and fresh-cut produce (mainly leafy green vegetables and tomatoes). Novel intervention technologies with higher efficacy of pathogen reduction will be developed and optimized. The impact of efficacious chemical and physical intervention technologies on sensory properties, nutrients, and shelf-life will be determined using the intensity (time, concentration, dose, etc.) that achieves a 3-log CFU/g reduction of the pathogens. In addition, new antibrowning/antimicrobial formulas will be developed to minimize risk of L. monocytogenes contamination during processing of cut fruit while inhibiting tissue browning. Furthermore, accumulation of chemical by-products as a result of chemical sanitizers and physical interventions will be investigated. Antimicrobial packaging as the final defense against human pathogens will be developed for a variety of food products (fresh-cut produce, meats, etc.) to reduce or control the re-growth of surviving pathogens during storage. Finally, combinations of efficacious intervention technologies with antimicrobial packaging will be evaluated for additive or synergistic inhibition of pathogens and preservation of product quality. Strategies and treatments will be developed to minimize adverse effects of intervention technologies and antimicrobial packaging on product quality. By combining efficacious intervention technologies and treatments with antimicrobial packaging, a 5-log reduction of common pathogens may be achieved. Intervention technologies either alone or in combination with antimicrobial packaging will be transferred to industry to enhance microbial safety of commercial food products.
3. Progress Report:
Organic acids are generally recognized as safe. Effects of common organic acids and electrolyzed water have been investigated as alternatives to chemical sanitizers for decontamination of fresh fruits and vegetables. Results indicate that organic acids such as acetic, lactic, malic, and citric acid can reduce the population of Salmonella spp. inoculated onto tomatoes by 96.8-99.9%. Some soft fruits such as tree-ripe apricots cannot be washed without damaging quality. Studies were conducted to evaluate the efficacy of ultraviolet light (UV-C) for inactivation of Salmonella and E. coli O157:H7 on tomato and apricot. Both Salmonella and E. coli O157:H7 populations decreased with increased doses of UV. Results suggest that a 10-second UV-C treatment can reduce 99% of Salmonella spp. and E. coli O157:H7 inoculated onto tomatoes or apricot. Salmonella exhibited slightly higher resistance to UV-C compared with E. coli O157:H7. In addition, UV light in combination with liquid phase ozone (1.4 parts per million) reduced 99.99% of Salmonella in an agitated system with surging bubbles. Antimicrobial coatings with edible and non-edible polymers and natural antimicrobials were developed for inactivating pathogens on shell eggs. Results show that the antimicrobial coatings were able to reduce up to 99.9999% of Salmonella cells on eggs. There was no re-growth of the pathogen on eggs after coating treatments and during the 28 days’ storage at 7 Degrees C. Results also indicated that the coatings were able to reduce the weight loss of eggs during storage at 7 or 4 Degrees C. Furan is a potential human carcinogen. The formation of furan was studied in model food systems as affected by heating, ultraviolet, and gamma radiation. Fatty acids and sugars as possible procurers of the compound were further investigated. Results suggest that changes in food composition would influence furan formation as a result of thermal and non-thermal processing. Based on one survey, one eighth of shrimp samples in the U.S. market is contaminated with L. monocytogenes, a pathogen causing listeriosis. The antimicrobial effects of ozone, antimicrobial coating, and cryogenic freezing, used alone or in combination, on survival of Listeria innocua (a surrogate of L. monocytogenes) on shrimp were investigated. Results indicated that antimicrobial coating in combination with cryogenic freezing reduced more than 99.999% of L. innocua and natural bacteria. The antimicrobial activity of three essential oils and their major components were evaluated as a gaseous treatment to reduce Salmonella Typhimurium on tomatoes. Texture, color, vitamin C, and lycopene contents of tomatoes were also analyzed after treatments. Results showed that treatment with gaseous cinnamon and oregano essential oils reduced Salmonella on tomatoes by 99.99% and maintained quality of the fruit.