13-11 |
Design and development of a post-package pasteurization process to inactivate Listeria monocytogenes in ready-to-eat meat products |
C. Corvalan1, T. A. HALEY2, and O. H. Campanella1. (1) Department of Agricultural and Biological Engineering, Purdue University, 1146 Agricultural and Biological Engineering Building, West Lafayette, IN 47907, (2) Department of Food Science, Purdue University, 1160 Food Science Bldg, West Lafayette, IN 47907 Numerous studies have been conducted to improve pasteurization processes designed to eliminate Listeria monocytogenes (LM) on meat products. Despite these advances, recontamination during slicing and final packaging can occur after the meat has been pasteurized. Consequently, the potential exists for surfaces of packaged, sliced, ready-to-eat (RTE) meat products to be contaminated with LM. As LM can grow at refrigeration temperatures, the presence of viable cells in refrigerated RTE meat products is a risk factor that endangers the public health. To confront this problem, our goal was to design a post-package pasteurization process to eliminate potential LM recontamination in sliced RTE meat products. Our approach was to use computer-aided process design. This approach obviates the need for expensive and repetitive experimental testing and incorporates flexibility for potential changes in processing conditions Experimental survival data at different temperatures were obtained for LM inoculated on bologna samples. This data was used to determine a model for death-rate kinetics based on the Weibull distribution. Thermo-physical properties of bologna were also measured and incorporated along with the microbial inactivation model into a finite element program to predict the product's temperature profile and resulting microbial lethality. Simulations provided the pasteurization parameters necessary to achieve a 3D logarithmic reduction of LM at the slowest heating zone and showed how these parameters depend on thermophysical properties, death-rate kinetics and package geometry. It was also found that the Weibull distribution was an excellent model for describing both lag and exponential death phases of LM. The method developed improves safety and quality in processed RTE meat products. The method is flexible and can determine appropriate pasteurization parameters for products of any dimension and formulation and for target microorganisms with any thermal death kinetics. The model can also be used to determine the optimal process response to deviations in processing given suitable constraints on microbial safety and product quality.
Session 13, Food Engineering: Thermal processes
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