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Mathematical Modeling Pathogen Reduction and Survival in Ground Meat


Evaluate, via laboratory research methods and mathematical modeling, the reduction and survival of Foodborne pathogens in ground meat (beef, pork or turkey) cooked to an internal temperature of 71.1 degrees C (beef and pork) or 73.9 degrees C (turkey) using consumer style cooking methods. <OL> <LI> Confirm differences in heating rates for consumer style cooking methods (single and double sided cooking). (year 1) <LI> Apply existing mathematical models to see how well they predict the data collected. (year 1) <LI> Modify the models to explain the new data. (year 2) <LI> Verify the models with new data. (year 2/3) <LI> Suggest new recommendations for consumers for cooking ground turkey, beef and pork. (year 3)

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NON-TECHNICAL SUMMARY: By establishing the variable survival of Foodborne pathogens in ground meats cooked by different consumer style cooking methods we can make recommendations for selected consumer cooking procedures that will avert food borne illness in the home. This will result in decreased suffering, time lost from work and medical expenses.

APPROACH: Various mathematical models have been published that might explain the decrease in cooking time and increased lethality when using double-sided grills for surface cooking, compared to single sided grills. Some researchers use first order inactivation kinetics models. (AMI, 2003, USDA Pathogen Modeling Program, 2003), but several researchers have suggested more robust methods including non-linear models to correct for variation in thermal conductivity and mass transfer and other factors that lead to non-linear lethality. These models are based on the finite difference methods for heat transfer and have been shown to be useful for predicting and optimizing commercial cooking methods. For example, Singh and his group have used this method to predict cooking time needed for microbial safety when using industrial double sided cooking (Pan et al., 2000; Pan and Singh, 2001; Singh, 2000; Zorilla and Singh, 2001). They stressed the need for verification at different fat levels and moisture contents during the cooking process. Ikediala et al. (1995) developed and verified a model to predict safe cooking parameters for single sided cooking (frying pan) of ground beef, with and without flipping. Marks has published an excellent overview (Marks, 2003) of the appropriate models to use when cooking meats (commercially) that require a verification of lethality (most ground, mechanically tenderized or injected meats). As he states: There is still a need to further extend the methods of quantitative microbiology by coupling the inactivation models with validated process (heat and mass transfer) models to evaluate the lethality of commercial cooking systems. We agree and are proposing to expand this concept to consumer cooking conditions.

Kang, Dong-Hyun; McCurdy, Alan
Washington State University
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