1a. Objectives (from AD-416)
The overall goal of this project is to enhance seafood safety, with special emphasis on catfish, through the development of new technologies and new original scientific information. The specific objectives are as follows: 1. Develop and validate models to simulate pathogen behavior under both growth and inactivation conditions. 2. Develop and validate non-thermal and advanced thermal intervention technologies to inactivate pathogens and spoilage microorganisms in raw and ready-to-eat seafood and aquaculture products, in particular, catfish. 3. Define the impact of non-thermal and advanced thermal intervention technologies on food quality and chemistry. It is expected that Objective 1 will contribute to the overall goal of this project through the development of new robust foodborne pathogen growth models that will aid regulatory agencies in their risk assessments and science-based policy decisions. Objectives 2 and 3 will contribute through the development of intervention technologies, which at the same time will enhance, or at the minimum, preserve the original product quality.
1b. Approach (from AD-416)
The incidence of foodborne illness associated with the consumption of contaminated seafood is disproportionately high. This project constitutes a comprehensive research effort to enhance seafood safety, with special emphasis on catfish. This will be accomplished through: 1) developing robust foodborne pathogen growth models to aid risk assessors in regulatory agencies in science-based policy decisions, 2) developing effective intervention technologies, and 3) enhance or, at the minimum, preserve seafood-quality. Intervention technologies to be investigated include flash pasteurization, pulsed and ultraviolet light, and ionizing (gamma) irradiation, electrolyzed water, modified atmosphere packaging, and GRAS food additives, etc. These interventions will be combined to obtain incremental improvements in microbial inactivation, the so-called hurdle to maximize foodborne pathogen inactivation. Food quality evaluation, studies will be conducted on the seafood subjected to various intervention methods to identify those technologies, which in addition to being effective in inactivating pathogens, are simultaneously neutral or even improve product quality.
3. Progress Report
This project has just recently been approved by OSQR. Research towards meeting the project’s first year milestones has been initiated in order to address NP108 Food Safety Goals (Components 1D - Pathogen Toxins and Chemical Contaminants – Intervention Strategies, 2D – Pathogen Toxins and Chemical Contaminants – Processing Intervention Strategies). As part of the research continued from 1935-42000-054-00D, research conducted with worked with two 1890s institutions (Delaware State University and Cheyney University) and USDA FSIS to determine the microbiological quality and incidence of chemical contaminants of retail catfish in the northeast U.S. has continued and the results to date have been reported to USDA FSIS. The use of process interventions to control foodborne pathogens and spoilage bacteria on whole catfish immediately prior to processing using electrolyzed water anolyte, ultraviolet light, and flash pasteurization has been initiated, with the catfish being obtained from the USDA-ARS Catfish Genetics Laboratory in Mississippi. Research on the use of cryogenic freezing, electrolyzed water anolyte, ultraviolet light, microwaves, and GRAS antimicrobials for control of foodborne pathogens on catfish fillets has been initiated. Growth studies required for development of models to predict pathogen behavior on catfish fillets have been initiated. In other research, preliminary studies were conducted to determine the precedence of foodborne pathogens including Salmonella spp., Staphylococcus aureus, Escherichia coli O157:H7, Listeria monocytogenes, and Vibrio spp. in raw frozen shrimp has been initiated. To date approximately 75% of the samples processed have tested positive for pathogenic vibrio species and approximately 10% have tested positive for Listeria monocytogenes. This has resulted in the initiation of research on the use of intervention technologies including cryogenic freezing, electrolyzed water anolyte, flash pasteurization, ultraviolet light to control foodborne pathogens in crustaceans. We expect to fully meet the required first-year milestones listed for completion in FY2012.
1. Inactivation of foodborne pathogens on crawfish meat by cryogenic freezing and gamma radiation. Seafood, including crawfish meat, is occasionally associated with foodborne illness outbreaks in the U.S. In order to provide a solution to this problem, and assist the U.S. Food and Drug Administration (FDA) evaluate a petition to allow treatment of crustaceans with ionizing radiation to control foodborne pathogens, the radiation D-10 values (the radiation dose needed to inactivate 90% of a foodborne pathogen) were determined on frozen crawfish meat by ARS researchers at Wyndmoor, PA. Because the majority of seafood sold in the U.S. is sold frozen, or frozen and then thawed prior to sale, the effect of freezing on foodborne pathogen survival was determined using a pilot scale commercial cryogenic freezer. Cryogenic freezing (-85 deg C, 3 min) inactivated over 70% of Salmonella spp., Vibrio spp., and Escherichia coli O157:H7 that was inoculated onto crawfish meat. Cryogenic freezing had no effect on the survival of Listeria monocytogenes and Staphylococcus aureus. The radiation D-10 values were 0.81, 0.58, 0.50, 0.49, and 0.36 kGy for L. monocytogenes, S. aureus, Vibrio spp., and E. coli O157:H7, respectively. This study met the goal of providing crawfish processors new pathogen inactivation values that can be attributed to cryogenic freezing, which can be included as part of their Hazard Analysis and Critical Control Point Plans. In addition, this research met the goal of providing the FDA with radiation D-10 values needed to evaluate the petition to allow irradiation of crustaceans (including crawfish) in the U.S.
2. Decontamination of whole fish by flash pasteurization. Seafood is occasionally associated with foodborne illness outbreaks in the U.S. Research by ARS researchers at Wyndmoor, PA, demonstrated that decontamination of catfish surfaces by flash pasteurization immediately prior to processing reduces microflora that can be transferred to finished fillets, and thus extend the fillet shelf-life. Flash pasteurization, a process that uses short bursts of steam to inactivate microorganisms on food product surfaces, and has minimal impact on product quality, was used to decontaminate whole catfish surfaces. Flash pasteurization (2 seconds steam, 115 deg C) inactivated >90% of mesophilic bacteria and >99% of psychrotrophic bacteria on catfish surfaces. Similar results were obtained using whole butterfish, black porgy, and white perch. The results of this research will allow seafood processors to decontaminate fish surfaces immediately prior to processing, allowing them to make safer fish fillets with extended shelf-life.