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:
Seafood is responsible for more cases of foodborne illness when adjusted for per capita consumption than beef, poultry, or produce. Initial research focused on assessment of spoilage bacteria, the incidence and prevalence of Salmonella spp., and the heavy metal and banned veterinary drug residues on retail catfish fillets sold in the north east United States in cooperation with Delaware State University and Cheyney University as part of research funded by USDA Food Safety Inspection Service. All project deliverables met, and the results were transferred to FSIS. In cooperative research between ARS researchers in Wyndmoor, PA and Mississippi State University the growth of foodborne pathogens in seafood including Salmonella in yellow fin tuna and non-O157: H7 shigatoxin producing Escherichia coli in catfish at refrigeration and abuse temperatures (5, 10, 15, 22 and 30 degrees C) was evaluated (Objective 1). This completed research fills a gap in the field of predictive microbiology since models which predict the growth and allow the assessment of risks associated with consumption of contaminated seafood. In other research a new microwave system with automatic feedback control to provide more even heating of fish fillets was used, in combination with a phosphate solution, to improve the quality of microwave cooked seafood. The new approach to microwave cooking produced catfish fillets with improved quality while inactivating 99.999% of the foodborne pathogens Listeria monocytogenes, Salmonella, and Escherichia coli. Significant progress (Objective 2 and 3) has been made in developing and validating ultraviolet light (UV-C) for decontamination of seafood and food contact surfaces (Objective 2 and 3). ARS researchers in Wyndmoor, PA demonstrated the ability of a commercial UV-C conveyor to inactivate 90-150% of the foodborne pathogen surrogate F. tularensis Utah-112 on catfish and tilapia fillets and >99.99% inactivation of the microorganism suspended in fish exudates on stainless steel and plastic food contact surfaces. In new developments research collaborations have been initiated with scientists from the U.S. Food and Drug Administration to develop and validate nonthermal processing technologies for inactivation of histamine producing bacteria on seafood. Research collaborations have also been initiated with a large east coast seafood processor and distributor to assess the effectiveness of nonthermal interventions in an actual commercial processing environment.
1. Predictive microbiology for the growth of foodborne pathogens on seafood. When adjusted for per capita consumption, seafood is associated with food borne illness more than beef, poultry, or produce. Little or no models exist to predict foodborne pathogen growth in seafood. ARS researchers at Wyndmoor, Pennsylvania, in cooperation with researchers at Mississippi State University, assessed the growth potential of spoilage microorganisms and foodborne pathogens on seafood including catfish fillets and yellow fin tuna. Growth curves at 5, 10, 15, 22 and 30 degrees C were completed for non-O157:H7 shigatoxin producing Escherichia coli inoculated onto catfish and Salmonella inoculated onto yellow fin tuna. This research fills a much needed gap in the field of predictive microbiology and will assist seafood processors and regulatory agencies assess risks associated with consumption of both properly refrigerated and temperature abused seafood which has become contaminated with foodborne pathogens.
2. Microwave cooking impact on pathogen inactivation on catfish fillets. When adjusted for per capita consumption, seafood is associated with food borne illness more than beef, poultry, or produce. Microwave cooking is used extensively at consumer, wholesale and retail levels, which can include the cooking of seafood. However, microwave cooking can be uneven, resulting in cold spots, and allow the survival of foodborne pathogens. ARS researchers at Wyndmoor, Pennsylvania designed a microwave oven (1250 watts) which used automatic feedback (80-90 degrees C/ 2 min) and a specially formulated phosphate solution to enhance even cooking of catfish fillets. The Food and Drug Administration recommendation for a 5 log (99.999%) reduction of foodborne pathogens including L. monocytogenes, Salmonella, and E. coli O157:H7 were attained, without damage to the quality of the fish fillets normally attributed to microwave cooking. These results will help the microwave and food service industries provide safer microwave cooked seafood products to consumers.
3. Inactivation of Francisella tularensis Utah-112 in fish and fish exudates using ultraviolet light. When adjusted for per capita consumption, seafood is associated with food borne illness more than beef, poultry, or produce. In this study, ARS researchers at Wyndmoor, Pennsylvania used ultraviolet light (UV-C, 254 nm) to inactivate the avirulent foodborne pathogen surrogate F. tularensis Utah-112 on catfish and tilapia fillets and their exudates inoculated onto food contact surfaces. When Utah-112 was suspended in catfish and tilapia exudates and placed on stainless steel and plastic food contact surfaces, which were then passed through a commercial UV-C conveyor, 0.5 J/cm2 inactivated >99.99% of the microorganism. UV-C (1 J/cm2) inactivated 90 and 150% of Utah-112 inoculated on catfish and tilapia fillets, respectively. UV-C had no negative impact on fish fillet quality. This study demonstrates the effectiveness of UV-C for decontamination of fish and food contact surfaces using actual commercial equipment. This will assist seafood processors provide safer products to consumers.
4. Seafood, when adjusted for per capita consumption, is associated with foodborne illness more than meat, poultry, or produce. In research conducted by ARS researchers at Wyndmoor, Pennsylvania, catfish fillets were rinsed with near-neutral electrolyzed water (anaolyte) having a pH of 6.0-6.5 and an oxidation reduction potential greater than 700 mV. Catfish fillets which were inoculated with Salmonella were treated with anolyte with a residual chlorine level of 300 ppm for 3 minutes. The treatment reduced Salmonella levels by 90%. In addition, Salmonella levels did not increase when the catfish fillets were held for 8 days at refrigeration (4C) temperature. The treatment with anolyte had no negative effect on catfish fillet quality. This method can be used by seafood processors to provide safer fish fillets to consumers.
Sommers, C.H., Rajkowski, K.T., Sheen, S., Samer, C., Bender, E. 2011. The effect of cryogenic freezing and gamma irradiation on the survival of Salmonella on frozen shrimp. Journal of Food Processing and Technology. DOI: 10.4172/2157-7110 S8-001.