Abstract:
Osmotic dehydration is a simultaneous mass transfer process which mainly promotes the flow of water molecules from the food to osmo‐active solution and some migration of solutes from the solution into the food, thus maintaining good organoleptic and functional properties in the finished product. Main parameters that affect the osmotic dehydration process are the salt concentration, soaking time and soaking temperature. In this study air assisted osmotic drying was investigated and the effects of salt concentration, soaking temperature, soaking time, air drying time, and air-drying temperature was considered on the drying process of tomato slices. The results revealed that the samples treated for 20 % (w/w) salt concentration and 40 0C and 9 hour generally have faster drying rates. The kinetics of ambient air assisted osmotic drying of tomato slices was studied and the logarithmic model had better represent the weight loss because it had higher R2 (98.24 %) better than Newton and Henderson models. Maximum hot air assisted osmotic drying of tomato slice drying was achieved at 80 0C temperature and 15 m/s air velocity. The hot air assisted osmotic drying kinetic model developed by Henderson and Pabis approach.
Finally, the quality analysis like lycopene content, pH, Vitamin C content, titratable acidity (TA) and total suspended solid (TSS) were conducted for fresh and dried tomato samples. The TSS content of the dried tomato was increased by 48.29 % from the fresh this is due to the addition of salts during osmotic drying. The lycopene content increased 10.72 % and 23.7 % of vitamin C was lost after osmotic treatment.