Modeling of Total Soluble Solid and NaCl Uptake during Osmotic Treatment of Bell Peppers under Different Infusion Pressures

Abstract

The uptake of sorbitol and sodium chloride in slabs of green bell pepper (10 × 10 × 2 mm) osmotically dehydrated at different concentrations of sodium chloride (30, 40, and 110 g/L) and sorbitol (7°Bx, 24°Bx, and 41°Bx) at different pressures (4.05, 44.66, and 85.33 kPa) with infusion times ranging from 6 to 60 min for sorbitol and up to 36 min for NaCl was evaluated. Models that describe the uptake of these solutes were developed under different experimental conditions. A completely randomized 3 × 3 factorial design was used to study the effect of the process variables on uptake of solutes for both sorbitol and NaCl. The uptake kinetic of solutes for both sorbitol and NaCl increased to an asymptotic level with both solution concentration and pressure. A negative exponential model adequately fitted the kinetics for both solutes with R 2 = 0.97 and 0.94. The best conditions for the highest increase in total soluble solids during sorbitol solution infusion were 4.05 kPa of pressure and 16 min of immersion. NaCl uptake in peppers followed an exponential trend without reaching the equilibrium conditions. The fitted models were found adequate to estimate that the increase in total soluble solids and NaCl in bell peppers during osmotic process can be used to establish pretreatment conditions in the drying process.