A control strategy to assure safety conditions in the thermal treatment of meat products using a numerical algorithms

Abstract

A finite element computational code was programmed in Matlab language to establish time–temperature specifications, in order to assure thermal inactivation of Escherichia coli O157:H7 in black sausages, produced in small scale plants. Even though the heating system in these plants may have a temperature control operating on the gas burners, the immersion water temperature can decrease significantly if the load ratio (sausage/water mass) increases; the thermal inertia of the system makes it difficult to re-establish this temperature instantaneously. The effect of the ratio between the amount of thermally treated sausages and the heat capacity of the system, on the temperature drop in the water bath, was mathematically simulated and experimentally validated. Computer simulations were performed by coupling the numerical solution of the microscopic heat conduction equation in the product with the macroscopic heat balance, which considers the heat flux of the gas burners. The model satisfactorily predicted experimental time–temperature results (mean error less than 5%) and constitutes a useful tool for meat processors and plant operators since it allows to determine adequate time–temperature conditions as a function of load ratio and initial water temperature, combining the microbial lethality kinetics with the main program.