FOOD STERILIZATION BY ELECTRICAL HEATING - SENSITIVITY TO PROCESS PARAMETERS

The design of efficient continuous sterilization equipment for flowing solid-liquid food mixtures requires that temperature and velocity dis tributions within the fluid are known. In electrical (ohmic) heating, electric current is passed through a two-phase mixture, and heat gener ated as a result of the resistance of the food acts to sterilize it. T his allows rapid sterilization of solid-liquid mixtures which minimize s quality loss. A computational process model simulates the effect of realistic physical property changes. The effect of variations in physi cal properties can have a significant effect on the temperature of the product and thus on its sterility. Realistic designs will have to cop e with temperature differences between phases. Experimental data for v elocities in a food flow have been incorporated into an enthalpy balan ce model for heat transfer in solid-liquid mixtures. The effect of inl et temperature on the length of hold tube required to give the necessa ry process sterility calculated shows the variation in output conditio ns that might result in real systems.