MODELING AND OPTIMIZATION OF THE PULSED VACUUM OSMOTIC DEHYDRATION (PVOD) PROCESS OF CARROTS IN A TERNARY SOLUTION BY RESPONSE SURFACE METHODOLOGY

Optimization of the pulsed vacuum osmotic dehydration (PVOD) process of carrot slices in a ternary solution was carried out using the response surface methodology. During PVOD, the vacuum pulse was applied at the beginning of the process for 10 min at a reduced pressure of 500 mm of Hg throughout all the experiments. After that, the osmotic dehydration process was continued at atmospheric pressure according to the central composite rotatable design (CCRD). The effects of temperature (35-55oC), sugar concentration (40-50oBrix), salt concentration (5-15%) and osmosis time restored at atmospheric pressure (10-240 min) on the responses viz. water loss (WL), solute gain (SG) and colour difference (∆E) of the dehydrated samples were assessed and statistically optimized through the desirability function approach. The models obtained for water loss, solute gain and colour difference were found suitable to describe the experimental data. It was found that the time restored at atmospheric pressure has the most significant effect on the responses at the 95% confidence level. The optimum condition was found at a temperature of 50oC, sugar concentration of 45.47oBrix, salt concentration of 7.50%, and restoration time of 67.50 min. At these optimum conditions, the water loss, solute gain and colour difference were 42.61%, 10.42% and 4.38, respectively. The predicted optimum values for independent linear variables were validated by performing triplicate experiments and the simulated data were come across similar with the experimental ones.