FEASIBILITY OF THE USE OF A TIME-TEMPERATURE INTEGRATOR AND A MATHEMATICAL-MODEL TO DETERMINE FLUID-TO-PARTICLE HEAT-TRANSFER COEFFICIENTS

The growing interest in mathematical modelling of heat transfer to het erogeneous foods, i.e. foods comprising a liquid and solids, forces fo od technologists to look for adequate input parameters for these model s. Here, possibilities of the combined use of a mathematical model and a Time-Temperature-Integrator (TTI), suggested to determine the fluid -to-particle convective heat transfer coefficient (h(fp)) in condition s which prohibit the use of conventional measurement techniques, is co nsidered theoretically. The relative importance of the kinetic charact eristics of the TTI, the carrier material, the location in/on this car rier, the immersion temperature and immersion time are systematically studied for idealized modelled processing conditions. The feasibility of existing TTIs and experimental results previously obtained with thi s methodology are critically evaluated. This theoretical study indicat es that this technique should be used with extreme caution and that th e response of each TTI towards different boundary conditions in a spec ific processing condition should be identified prior to experimentatio n. The need for such an a priori sensitivity study, specific for each processing condition, TTI and carrier material makes it a cumbersome m ethodology.