Critical limits in a cooking process to eliminate bacteria

Abstract

A major risk to the food processing industry worldwide is the impact of microbial growth that causes food-borne illnesses. The Food and Drug Administration (FDA) created a systematic approach for establishing food safety in the food supply of astronauts. The USDA required most meat and poultry plants to start using the approach called Hazard Analysis Critical Control Point (HACCP) by January 1999. This thesis is focused on the HACCP principle of establishing critical limits. More specifically, it is directed at the critical limits in a cooking process to eliminate bacteria while still producing a quality product in a cost effective manner. This will be achieved by using both one and two-dimensional temperatures profile to evaluate different cooking methods and duration of the cooking process and determining the impact of elapsed time between the cooking and freezing process. The temperature profile was obtained by solving the transient governing equations using the Gauss-Seidel iterative method. Second order central difference method was applied to the convection and conduction terms of the governing equation. The temperature profiles of chicken, beef and potato food products were compared for different values of Peclet number (Pe) and Biot number (Bi). The one-dimensional temperature profile was used to compare energy changes and the two-dimensional temperature profile was used to examine the temperature gradient across the food product. The results show that for thick products a manufacturer should use a low Bi cooking method to allow conduction through the food product without burning the surface and higher Pe values are beneficial to partial cooking processes where only the outer surface requires cooking.