Influence of some process conditions on the rehydration of apple cubes

Dried fruit and vegetables are widely used as ingredients in many food form ulations such as pastries, confectionery products, ice-creams, frozen desse rts and yoghurts. The different water content of the dried fruit in respect to that of other ingredients may enhance the mass transfer (water or solut es) with problems of phase separation or lass of textural properties. Never theless it is not easy to obtain, only by a drying treatment, fruit pieces with "adjusted" a(W) values; hence, it could be profitable to have a standa rd dried fruit rehydrated in water or sugar solutions under appropriate con ditions in order to obtain an optimum a(W) value. In this work, different rehydrating trials have been carried out on air dri ed apple cubes by varying the rehydration medium concentration (from 0 to 3 0 degrees Bx), temperature (from 20 to 80 degrees C) and agitation rate (fr om 0 to 250 r.p.m.). During rehydration, water content, water uptake and so lid loss or gain of samples were measured. Results have shown that the rehydration time was the main important paramet er for the water uptake and for the solid loss, while the medium concentrat ion influenced only the solid gain of apple cubes.