Mass exchange during osmotic pretreatment of vegetables

Apple, pumpkin and carrot were used to study mass transfer during osmotic d ehydration of plant tissue. Osmotic dehydration was carried out in 61.5% so lution of sugar. Temperature of dewatering was constant at 30 degreesC. Tim e of dehydration was varied from 0 to 180 min. Osmotic dehydration in sugar solution at 30 degreesC depends on the kind of plant tissue. The most sign ificant changes of water content, water loss and solids gain took place dur ing the first 30 min of dewatering. During that time water content in apple s was reduced by some 48%, whereas further dehydration from 60 to 180 min r esulted in water content reduction by next 30%. Further dewatering of pumpk in and carrot proceeded much slower than that at the beginning of the proce ss. Rate of water loss was 5-10 times higher than the rate of solids gain a nd depended on the advancement of the dewatering process. (C) 2001 Elsevier Science Ltd. All rights reserved.