A combined convection cooking and Salmonella inactivation model for ground meat and poultry products

A predictive model for moist-air impingement cooking of ground-and-formed meat and poultry products was developed. A coupled heat and mass transfer model incorporating the effects of fat transfer was combined with a model for Salmonella inactivation, to produce a complete prediction tool for meat and poultry processors. The model utilized the finite element method to numerically solve separate equations for heat, moisture, and fat transport. These equations were coupled through boundary conditions and interdependent thermo-physical property relationships. An enthalpy formulation for heat transfer was utilized to avoid discontinuities related to solid-to-liquid phase changes of water and fat within the product. Boundary conditions unique to moist-air impinging flow were incorporated into the model. These boundary conditions accounted for the additional heating effects of surface condensation that are common within moist air impingement systems.; To complete the fat transport component of the model, laboratory experiments were conducted to determine the fat holding capacity of ground beef as a function of temperature and initial fat content. Fat holding capacities ranged from 0.05 to 0.6 g fat/g nonfat dry matter, and a polynomial model was parameterized to those data.; Additionally, laboratory-scale, moist-air convection cooking tests were conducted to confirm the importance of fat transport. Species and initial fat content significantly affected (P < 0.05) cooking time, yield, and fat loss for ground beef, pork, and turkey. The heating time required to reach 85°C varied by as much as 217 seconds between different fat contents of the same species. Differences in cooking yield of up to 18% were measured between different fat contents. Fat transport was responsible for up to 28% yield loss in high fat products.; Finally, cooking experiments using an industrial moist-air impingement cooking system were used to validate the temperature, moisture, and yield predictions of the complete cooking model. The cooking model predicted transient patty center temperatures with a standard error of prediction of 8.0°C for 54 cooking tests. At temperatures above 45°C, the standard error of the prediction was 5.8°C. The standard error for final moisture content predictions was 2.3% wet basis. Standard error for final cooking yield predictions was 6%. Additional comparisons were conducted between the cooking model and published data collected from moist-air impingement ovens. Data from published sources were used to perform a verification of the Salmonella inactivation predictions of the model. The standard error of prediction for Salmonella inactivation was 1.3 logs (CFU/g).