Optimization of Osmotic Dehydration Process for Aonla (Emblica officinalis Gaertn) Pieces with Salt Solution and Spices by Response Surface Methodology

Abstract

The optimization of osmotic dehydration process of aonla (Emblica officinalis Gaertn) slices in brine solution containing spices (cumin powder, fenugreek powder, fresh ginger extract) was carried out using response surface methodology. The independent process variables for osmotic dehydration are salt concentration in water (4-12%), spices concentration in the brine solution (39%), solution to fruit ratio (3-5) and duration of 60-90 minutes at room temperature. The osmotic dehydration process was optimized for maximum water loss, solute gain, overall acceptability and minimum acidity and vitamin C loss based on the RSM. The optimum conditions were predicted as 12% salt concentration, 7.09 % spices concentration, 4.30 solutions to fruit ratio and 84.15 minutes process time. Among the process variable, salt concentration, process duration and spices concentration have the most significant effect on water loss, solute gain, acidity and overall acceptability; process time has the most effect on vitamin-C loss and acidity whereas solution-to-fruit ratio had significantly lower effect on all the responses. Osmotically dehydrated aonla samples were observed to be less in functional compounds compare to fresh aonla samples due to leaching out of minor compounds to hypertonic solution during osmotic dehydration process.