Analyses of control parameters for osmotic dehydration in an automatic experimental system: Application to the treatment of Golden Delicious apples

The work presented here is a study aiming at the control and checking of de watering and impregnation soaking process (DISP). The studies are carried o ut using an automatic experimental system. Apples of the "Golden" variety a re used exclusively. Two kinds of agitation system are studied; mechanical agitation using a vertical screw without an end, and hydraulic agitation. T here is hardly any difference between the two kinds of agitation; parameter variations are almost the same. These results are compared with those obta ined in agitated thermostated water-bath system and they show that mass tra nsfers are better on the experimental system than with the water-bath syste m. Temperature influences were studied for the agitated thermostated water- bath system only. They show that the increase of temperature favours water loss and sugar intake. We have shown that during experiments with old syrup , only the conductivity of syrup is higher but kinetics of water loss, solu te intake and weight reduction are not significantly affected. (C) 2001 Els evier Science Ltd. All rights reserved.