Optimization of the Osmotic Dehydration Process of Kiwi Fruit

In this work was studied simultaneously seven factors affecting osmotic process of kiwifruit including osmotic agent (sucrose and sorbitol), temperature of osmotic solution (30 and 60 °C), immersion time (0.5 and 3 h), concentration of osmotic solution (30 and 60 ºbrix), the solution to material ratio (3/1 and 5/1), thickness of kiwifruit slices (5 and 20 mm) and coating of fruit slices prior to osmotic process. The responses of the experimental designs were the water loss (WL), weight reduction (WR), solid gain (SG) and normalized moisture content (NMC). The results showed that temperature of osmotic solution, immersion time, thickness of kiwifruit slices and concentration of osmotic solution were the most important factors affecting WL, WR, SG and NMC. Also, experimental data indicated sorbitol solutions affected the value of WL, SG and WR more than sucrose solutions that it could be related to the lower molecular weight of sorbitol. The results showed two solution to material ratio (3/1 and 5/1) had not significant effect on the amounts of WL, WR, SG and NMC (P>0.05). Our studies indicated that coating of kiwifruit slices by guar gum increased WL and WR and decreased SG while it had not considerable effect on the values of NMC. The optimum dehydration conditions were as follows:Thickness of kiwifruit slices = 5mm, immersion time = 3h, concentration of osmotic solution = 60 Brix, temperature of osmotic solution = 58.1C, the solution to material ratio = 5, syrup type = sucrose and coating before osmotic dehydration.

کلیدواژه ها:

Osmotic dehydration ، Optimization ، Kiwifruit.