DEHYDRATION KINETICS AND MODELLING

Abstract

This paper presents a study on the kinetics of dehydration of carrot parallelepipeds which may be useful for a new method which consists in applying a freezing pretreatment. followed by a vacuum dehydration after sample defreezing.allowing instant products to be produced in terms of rehydration ( about 2 minutes rehydration). in this paperare examined effects of effects of pressure (2.6 to 75 kPa). heating conditions (single and double face heating), temperature (50 to 100°c) and sample thickness (3 to 20 mm thick) on dehydration rate. Dehydration curves allow the identification of two main periods with variation of sample temperature during drying. The first period is a quasi-isothermal. falling-rate period characterized by a large quantity of moisture removal through diffusional transfer. Then. can be observed a second period with increase in product temperature while drying rate is governed by heat diffusion. A drying model accounting for sample shrinkage is proposed and discussed.