Optimization of process parameters for ultrasound‐assisted osmotic dehydration of pineapple slices using response surface methodology

Abstract

The effect of ultrasound assisted osmotic dehydration (USOD) on dehydration kinetics viz., water loss (WL), solid gain (SG) and osmotic dewatering rate (ODR) were investigated using response surface methodology, in order to optimize process parameters. Pineapple slices were subjected to USOD at three different osmotic solution concentrations (50, 60 and 70°B), sonication time (20, 30 and 40 min), temperatures (10, 20 and 30°C) using two types of osmotic agents (Glucose and Fructose) in an ultrasonic bath (ultrasound frequency of 33±3 kHz and ultrasound power of 250 W). Box-Behnken design was used as experimental design, consisting of three factors with three levels, and a categoric factor with two levels, totaling thirty four data points. Results of ANOVA and regression analysis conducted showed significant effects on responses and model’s best fit to the experimental data. Results revealed that USOD treatment led to higher water loss and osmotic dewatering rate compared to osmotic dehydration (OD). The optimized values that would give maximum WL, ODR and minimum SG were osmotic solution concentration of 50°B, sonication time of 26.6 min, temperature of 30°C and using Fructose as osmotic agent. This resulted in values of 0.266 g water/g, 0.049 g solid/g and 0.730 g/min for water loss, solid gain and osmotic dewatering rate, respectively.