BIOLOGICAL VALIDATION OF MATHEMATICAL-MODELING OF THE THERMAL-PROCESSING OF PARTICULATE FOODS - THE INFLUENCE OF HEAT-TRANSFER COEFFICIENT DETERMINATION

This paper describes a mathematical procedure to determine the lethality in a continuous sterilization system for foods containing large particles. A computer program to predict the temperature distribution within the flowing particles and heat lethality was developed using finite difference equations. The convective heat transfer coefficient between fluid and particles was experimentally estimated by means of a model system consisting of an immobile potato cube surrounded by a continuously flowing fluid. To verify this approach, a tubular heating-holding pilot plant was used for processing potato cubes in a NaCl solution. A biological validation of the mathematical model was carried out by inoculating the potato cubes with yeast cells and comparing the experimentally measured lethality values with those calculated using the computer program. Quite a good agreement was obtained between the model predictions and the experimental findings.