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United States Department of Agriculture

Agricultural Research Service

2008 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 nonthermal process interventions that specifically address Plan Component(s) 1.2.4 Processing Intervention Strategies. The most significant news has been the commercialization of the Flash (Steam) Pasteurization (FP) Process in cooperation with CRADA partners from Alkar-RapidPak, Inc. as noted in accomplishment 4A. Approximately 28 million lbs of sausages containing diacetate/lactate mixtures, valued at approximately $224 million, will be processed using FP in the U.S. in 2008. In addition, the FP/vacuum-steam-vacuum process, which was developed as part of a USDA-ARS/Industry partnership, has now been adopted by meat processors in both Central and South America. Research on FP, in combination with UVC light and new antimicrobials, is being conducted to improve its efficiency even more. Limitations currently exist on the types of microorganisms which can be subjected to the intervention due to pilot plant and equipment location issues. Significant progress has been made in the development of in-package infrared and microwave pasteurization systems with automatic feedback for temperature control that can be used to inactivate bacteria while limiting temperature effects on packaging materials and food quality which was hailed as a potential breakthrough technology by the Institute of Food Technologists, and has garnered a great deal of industry interest. Research in this area has been accomplished using bench-top equipment in older laboratory facilities. Additional progress in this field of research will require pilot scale/pathogen compatible laboratory space. The research group previously had to decline an offer of a free infrared tunnel and an industrial microwave due to facilities limitations. Research on the use of ultraviolet light (UVC) for surface decontamination of foods and food contact surfaces has identified and eliminated candidates for use of this FDA approved technology. UVC was found to inactivate 5 log of multiple pathogens (Listeria, Staphylococcus, Salmonellae) on four types of stainless steel used in food processing environments, and decreased the virulence of the surviving microorganisms. UVC was found to be amenable for inactivating foodborne pathogens on smooth surfaced foods including frankfurters and sausages (2 logs), tomatoes (3.5 logs), eggs (1 log). UVC reduced the pathogens by only 0.5 log on raw meat and poultry surfaces. UVC represents an inexpensive technology that can be used by small processors for improving food safety and collaborations are currently underway with Reyco, Inc. to develop the technology. A new area of research has been the use of nonthermal process interventions to improve the safety of seafood and aquaculture products. A CRADA has been signed with Air Products, Inc (Allentown, PA) for development of nonthermal interventions that can be used in combination with GRAS antimicrobials for improving the safety of individually quick frozen (IQF) raw and cooked seafood and aquaculture products.

NP 108 2006-2010 Action Plan Component 1.2.4. Processing and Intervention Strategies.

1. Flash Pasteurization Inactivation of Listeria on Frankfurter Surfaces: Frankfurters can occasionally become contaminated by the pathogen Listeria monocytogenes following cooking and prior to packaging, leading to product recalls and foodborne illness outbreaks. Flash (Steam) Pasteurization (FP) was used to inactivate Listeria innocua, a non-pathogenic surrogate microorganism, on the surfaces of frankfurters that contained the commonly used antimicrobials potassium lactate and sodium diacetate, in a pilot plant setting. FP inactivated 99 percent of Listeria on the frankfurters, and the antimicrobials prevented proliferation of the Listeria for 2 months under refrigerated storage conditions. The FP process, in combination with potassium lactate and sodium diacetate, is now being used by a major manufacturer of pre-cooked sausages to provide safer ready-to-eat meat products to consumers. Action Plan Component(s) 1.2.4 Processing Intervention Strategies.

2. Near-Infrared surface pasteurization of RTE Meats: Near-infrared (NIR) is an electromagnetic energy generated by a high temperature object. It has certain penetrative capability that can be used for both surface and sub-surface heating. A new NIR surface pasteurization technology was developed to inactivate Listeria monocytogenes on cooked chicken breast meats. This system was equipped with an automatic temperature control system to control the surface temperature of hotdogs. Using the laboratory infrared heating system, it was observed that the bacteria could be killed at an average rate of 0.4, 0.9, or 1.6 logs/min for the samples heated to and maintained at 62, 68, or 75C. One log of reduction represents a 90 percent decrease in the microbial population. Two logs represent a 99 percent decrease, etc. A 6 log (99.9999 percent)reduction of L. monocytogenes on chicken meats could be achieved within 3.6 min. This research provides the food industry with a new technology to eliminate L. monocytogenes in ready-to-eat meats. Action Plan Component(s) 1.2.4 Processing Intervention Strategies.

3. Ultraviolet Light Inactivation of Pathogens: Ultraviolet light (UVC) was used to inactivate the human pathogens Listeria, Staphylococcus aureus and Salmonellae on frankfurters, bratwurst, boneless skinless chicken breasts, chicken drumsticks, pork chops, tomatoes, eggs, and stainless steel. UVC inactivated 5 log of pathogens on stainless steel, 3.5 log on tomatoes, 2 log on eggs, 2 log on frankfurters and bratwurst, and 0.5 log on chicken and pork. One log of reduction represents a 90 percent decrease in the microbial population. Two logs represent a 99 percent decrease, etc. These data can be used by food processors to provide safer products for consumers. NP 108 Food Safety 2006-2010 Action Plan Component (s) 1.2.4 Processing Intervention Strategies.

4. Gamma radiation inactivation of Listeria on fish: Gamma irradiation was used to determine the D-10 reduction of Listeria monocytogenes on fresh and frozen catfish and tilapia. D-10 is defined as the radiation dose needed to reduce the microbial population by 90 percent (1 log). These bacteria are associated with foodborne illness outbreaks, and their serotypes used in our studies were isolated from finfish. Gamma irradiation was used to inactivate each isolate on the inoculated fresh and frozen product to determine the D-10 value. The D-10 value to inactive the bacteria on frozen finfish were higher than when thawed samples were used. The effect of irradiation on the lipid content of the fresh and frozen finfish was determined and no observed increase in lipid oxidation occurred at the levels studied. These data can be used by fish processors to provide safer products for consumers. NP 108 Food Safety 2006-2010 Action Plan Component (s) 1.2.4 Processing Intervention Strategies.

5.Significant Activities that Support Special Target Populations

6.Technology Transfer

Number of Non-Peer Reviewed Presentations and Proceedings1
Number of Other Technology Transfer1

Review Publications
Huang, L. 2008. Growth Kinetics of Listeria monocytogenes in Broth and Beef Frankfurters– Determination of Lag Phase Duration and Exponential Growth Rate under Isothermal Conditions. Journal of Food Science. 73(5):E235-E242.

Sommers, C.H., Geveke, D.J., Fan, X. 2008. Flash Pasteurization inactivation of Listeria innocua on frankfurters that contain potassium lactate and sodium diacetate. Journal of Food Science. M1-M3.

Huang, L., Sites, J.E. 2008. Elimination of Listeria monocytogenes on Hotdogs by Infrared Surface Treatment. Journal of Food Science. 73:M27-M31.

Rajkowski, K.T., Fan, X. 2008. Microbial quality of fresh-cut iceberg lettuce washed in warm or cold water and irradiated in a modified atmosphere package. Journal of Food Safety. 28:248-260.

Rajkowski, K.T. 2007. The survival of Shigella sonnei in frozen media and after ultraviolet treatment of ice and inoculated fish samples. Ice World Journal. 9:14-23.

Sommers, C.H., Rajkowski, K.T. 2008. Inactivation of Escherichia Coli JM109, DH5 ALPHA and O157:H7 Suspended in Butterfields Phosphate Buffer by Gamma Irradiation. Journal of Food Science. 73(2):M87-M90.

Last Modified: 11/29/2015
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