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United States Department of Agriculture

Agricultural Research Service


Location: Food Safety and Intervention Technologies

2010 Annual Report

1a.Objectives (from AD-416)
To reduce the risk of food borne illness associated with the consumption of meat and poultry, seafood and aquaculture, and complex ready-to-eat foods while maintaining product quality and extending shelf-life. The specific objectives of the research program are as follows: .
1)Utilize microbiological and molecular techniques to determine the effect of intervention technologies on microbial physiology, virulence and injury in order to assist in the design of effective process interventions;.
2)Develop and validate nonthermal and advanced thermal intervention technologies such as ionizing and UV radiation, radio-frequency and microwave heating, vacuum-steam-vacuum processing and ozonation to inactivate pathogens and spoilage microorganisms in raw and ready-to-eat meat and poultry, seafood and aquaculture products, and related complex solid foods, in combination with GRAS food additives;.
3)Define the impact of non-thermal and advanced thermal intervention technologies on food quality and chemistry.

1b.Approach (from AD-416)
D-values and the growth potential in shelf-life studies will be determined for foodborne pathogens using inoculated products following application of non-thermal and advanced thermal technologies. Particular attention will be focused on the use of multiple technologies, commonly known as the hurdle approach, to inactivate pathogens in foods. The effects of intrinsic and extrinsic factors such as processing variables, and product composition (temperature, dose, atmosphere, GRAS additives, pH, moisture, etc.) will be determined. Effects of interventions on the chemistry of foods and the formation and biological effect of toxicological markers will be determined using GC and GC-MS based technologies and bioassays.

3.Progress Report
There has been significant progress in the development, validation, and commercialization of non-thermal and advanced thermal process interventions. Research to improve the safety and shelf-life of processed meats such as frankfurters and other ready-to-eat meats has largely been completed and we will conduct no additional research in this area. This includes research on the use of individual technologies, and combinatorial (the hurdle approach) use non-thermal and advanced thermal intervention technologies to improve the microbiological safety of ready-to-eat meats. Over the course of the project life this research has resulted in the commercialization of technologies including the dual use of infrared and hot water pasteurization (the hurdle approach) for inactivation of Listeria monocytogenes on large products by two Philadelphia area meat processors. With the cooperation of our CRADA partner, Flash Pasteurization in combination with antimicrobial compounds has been commercialized and is in use by companies in North, Central, and South America. In the last year our research on the use of ultraviolet light to decontaminate food and food contact surfaces has been transferred to, and put into practice by, the food processing industry. Our research on the safety of 2-alkylcyclobutanones was cited in the U.S. Food and Drug Administration approval for irradiation of mollusks, which contributed to the commercialization of ionizing radiation as a process to improve the safety of raw oysters in 2009. With the closing of research to improve the safety of ready-to-eat meats, our research efforts have shifted to support USDA FSIS Office of Catfish Inspection Programs in their 2008 Farm Bill mandated responsibility to take over inspection of catfish and catfish processing facilities. Project scientists are currently working with two 1890s institutions (Delaware State University and Cheyney University) in order to assist the USDA FSIS determine the microbiological quality and incidence of chemical contaminants of retail catfish in the northeast U.S.(see annual reports 1935-42000-054-04G and 1935-42000-054-05G). In addition, this project has been chosen to host and complete research for in-plant microbiological safety and quality of catfish needed by USDA FSIS Office of Catfish Inspection Programs for 2010 and 2011. We have initiated research on the use of alternative process interventions to improve the safety and shelf-life of catfish and other seafood products in support of USDA FSIS research needs at their specific request.

1. Inactivation of food-borne pathogens on frozen seafood using ionizing radiation: Contaminated seafood is responsible for a significant number of food-borne illness outbreaks and product recalls in the U.S. Ionizing radiation is a safe and effective technology for inactivating food-borne pathogens in seafood. ARS researchers at Wyndmoor, PA determined the radiation D-10 values for Salmonella spp., Listeria monocytogenes, and Staphylococcus aureus on frozen tuna, swordfish, octopus, squid, blue crab, cold and warm water lobster, and shrimp. The D-10 value (the radiation dose needed to inactivate 90 percent of the microorganism) of the three food-borne pathogens in frozen seafood were significantly lower than those obtained in frozen meat products. This research will assist the U.S. FDA in their evaluation of a petition to allow irradiation of crustaceans in the U.S. This work will help seafood processors provide the highest quality value-added products to export markets where irradiation technologies are currently approved.

2. Inactivation of food-borne pathogens on catfish skin by ultraviolet light: The food-borne pathogens Salmonella, Listeria monocytogenes, and Stapylococcus aureus were surface-inoculated onto catfish skin and treated with ultraviolet light. A ultraviolet light dose of 0.5 J/cm2/s inactivated 99 percent of the three pathogens on catfish skin. This technology developed by ARS researchers at Wyndmoor, PA could be used to help processors decontaminate catfish prior to processing into fillets and therefore provide safer catfish to consumers. It will also assist the USDA Food Safety Inspection Service Office of Catfish Inspection Programs in the development of science-based regulation development.

3. Ultraviolet light inactivation of Francisella tularensis Utah-112 on foods: Francisella tularensis is a bacterium of food security concern. F. tularensis Utah-112, which is not virulent to humans, was inoculated by ARS researchers at Wyndmoor, PA into frankfurters, bratwurst, veggie dogs, catfish and tilapia fillets, raw chicken and beef, tomatoes, agar plates and stainless steel. A ultraviolet light (UV-C) dose of 0.5 J/cm2/s inactivated 90 percent of the bacterium on raw meat and fish, 99 percent of the bacterium on frankfurters, bratwurst, and veggie dogs, and almost 99.99 percent of the bacterium on tomatoes. A UV-C dose of 4 mJ/cm2/s inactivated over 99.99 percent of the bacterium on agar plates and stainless steel. This research will allow appropriate federal agencies address food security needs.

4. Microwave with feedback technology: A temperature-controlled microwave oven was used by ARS researchers at Wyndmoor, PA for in-package pasteurization of a simulated product containing raw chicken breast meat and gravy. This microwave heating system, modified from a commercial inverter-based microwave oven (2245 MHz, 1.25 KW), and equipped with an infrared sensor and a data acquisition system, was used to cook chicken meat in gravy. A feedback temperature and power control program, based on LabView 8.6 (Professional Version), was used to control the power output of the microwave oven. A four-strain cocktail of Salmonella was used to inoculate the chicken meat. The inoculated product was heated in the microwave oven to inactivation of Salmonella. This study demonstrated that Salmonella inoculated onto raw chicken meat in the simulated product can be completely eliminated with a proper selection of heating strategies. This work will assist the U.S. FDA develop new time and temperature requirements for microwave cooking of poultry.

5. Inactivation of salmonella on catfish fillets by phosphates and freezing: Catfish will be inspected by the USDA Food Safety Inspection Service starting in 2011. The survival of Salmonella inoculated on catfish dipped in sodium tripolyphosphate (TSP), which were then individually quick frozen, was determined by ARS researchers at Wyndmoor, PA. The catfish fillets were held at -20C, which is the temperature used during shipping and storage. Recovery of Salmonella was done using TSA and XLT-4 agars. Results showed a 90 percent decrease of salmonella after 6 months of storage using nonselective TSA. A 99 percent difference was observed between the recoveries using TSA versus selective XLT-4 agar, indicating injury after freezing for the samples dipped in TSP. This work will help USDA FSIS Office of catfish Inspection develop their inspection programs.

Review Publications
Huang, L. 2010. Growth kinetics of Escherchia coli O157:H7 in mechanically-tenderized beef. International Journal of Food Microbiology. 140:40-48.

Sommers, C.H., Scullen, O.J., Sites, J.E. 2010. Inactivation of foodborne pathogens on frankfurters using ultraviolet light (254 nm) and GRAS antimicrobials. Journal of Food Safety. 31:1-12. Available:

Sommers, C.H., Sites, J.E., Musgrove, M.T. 2010. Ultraviolet light (254 NM) inactivation of pathogens on foods and stainless steel surfaces. Journal of Food Safety. 30(2):470-479.

Huang, L., Sites, J.E. 2010. A New Automated Microwave Heating Process for Cooking and Pasteurization of Microwaveable Foods Containing Raw Meats. Journal of Food Science. 75:E110-E115.

Huang, L., Sheen, S. 2010. Cooling of cooked RTE meats and computer simulation. In: Hwang, A. and Huang. L., editors. Ready-to-Eat Foods, Microbial Concerns and Control Measures. Boca Raton, FL: CRC Press, Taylor & Francis Group. p.191-228.

Last Modified: 4/16/2014
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