MULTICRITERIA OPTIMIZATION OF FOOD-PROCESSING COMBINING SOAKING PRIORTO AIR-DRYING

A method for multicriteria optimization is illustrated by the example of apples processed by Dewatering and Impregnation Soaking (DIS) in co ncentrated aqueous sucrose solutions, and then air dried. The influenc e of the product history (modifications linked to DIS treatment) on it s behaviour during drying process is assessed according to an experime ntal design. Five operating variables are taken into account: temperat ure, solution concentration and soaking time for DIS pre-step, and tem perature and relative humidity for air drying. Results show a limiting effect of internal water transport by the sucrose impregnated superfi cial layer. This effect can be reduced by drying at high temperature ( 80 degrees C) On the other hand, the relative humidity of air has litt le influence on the behaviour of soaked materials. Multicriteria optim ization takes into account six criterias and shows that stable and opt imal quality products can be obtained at interesting energetic costs a nd for a short processing time duration (50 to 300 min).