Ultrasound assisted osmotic dehydration of sweet lime (Citrus limetta) slices: Process optimization and mass transfer kinetics

Abstract

Sweet lime (Citrus limetta), known for its unique taste and aroma, is limited in use due to its bitterness. Osmotic dehydration of sweet lime slices was studied to optimize mass transfer kinetics using response surface methodology (RSM). The debittering pre-treatment using NaCl ranging from 0 to 5 % resulted in a significant reduction of bittering compounds, achieving a 39.40 % decrease in naringin and a 21.46 % decrease in limonin at 4 % NaCl concentration. Osmotic solution concentrations (60, 70, and 80°Brix) and ultrasound time (4, 8, and 12 min) were examined for optimization of osmotic dehydration. Ultrasound treatment enhanced mass transfer, reducing processing time while retaining vitamin C, though it altered the colour of the slices, significantly impacting L*, ΔE, and the browning index (BI). The optimal conditions for osmotic dehydration were found to be 80°Brix and 5.3 min as the solution concentration and ultrasound time. Under these conditions, predicted values for water loss (WL), solid gain (SG), weight reduction (WR), retention of ascorbic acid and ΔE were 90.71 g/100 g, 73.65 g/100 g, 15.33 %, 74.28 %, and 7.87 respectively. This method enhances mass transfer efficiency and vitamin C retention, facilitating the comprehensive utilization of sweet lime with minimal waste generation.