PREDICTION OF DEGRADING REACTIONS DURING DRYING OF SOLID FOODSTUFFS.

Nutrient loss during drying of a shrinking product was determined. A diffusion model that takes into account the shrinkage of the product in the mass balance equation was used, together with a simplified energy balance with no thermal gradients, and convective boundary conditions for both balances. Nutrient loss prediction was obtained, for first and second order kinetics. Finally, a new methodology was proposed, to determine the activation energy and the preexponential of the deterioration reaction, even when the differential equations that rules the drying process are unknown, and only the thermal history of the product is available. This approach is also valid for sterilization calculations, if temperature gradients can be neglected, i.e. when Biot number for heat transfer is small.