A COMPUTER-SIMULATION PROGRAM FOR EVALUATION OF THE CONTINUOUS HEAT-TREATMENT OF PARTICULATE FOOD-PRODUCTS .2. UTILIZATION

A computer program for calculation of temperatures in a liquid contain ing particles during continuous heat treatment has been developed at t he SIK. The program facilitates the study of the influence of processi ng on product quality in an aseptic processing system. The calculated F value is related to the safety, and the cook value (C value) is rela ted to the quality of the product. In this paper, results of some calc ulations using the program are presented. They concentrate on the infl uence of the processing conditions on the process design. These result s indicate that factors such as particle heat transfer coefficient, bo th in the holding tube and in the scraped surface heat exchangers (SSH Es), flow conditions, particle diameter and sterilisation temperature have consequences for the holding tube length, i.e. the processing tim e, for a given lethality. For example, for small particle heat transfe r coefficients (< 100 W m2 K), a small change will have a large effect on the required processing time (i.e. the holding tube length). Howev er, at particle heat transfer coefficients > 150-200 W m2 K a small ch ange does not greatly affect the processing time (i.e. holding tube le ngth). The program can thus be used to examine whether the surface hea t transfer coefficient is the rate-limiting factor, or whether the hea t conduction inside the particles is more important in the design of t he process.