Effect of Ultrasound-Assisted Pre-treatment on Osmo-Dehydration Kinetics and Quality of Star Fruit (Averrhoa Carambola L) Slices: An Optimization Study

Abstract

Ultrasound pre-treated osmo-dehydration of star fruit (Averrhoa Carambola L.), an underutilized tropical fruit was successfully employed and the process variables were optimized using response surface methodology (RSM). Ultrasound pre-treatment showed positive effects on osmo-dehydration with 4.36% higher water loss and 2.38% less solid gain. The effect of process variables slices thickness (ST), sugar concentration (SC) and immersion time (IT) was studied on water loss (WL), solid gain (SG), ascorbic acid (AA) and oxalic acid (OA). The value of a set of compromised process parameters ST, SC, IT was found to be 10 mm, 56°Brix, and 3 h, respectively resulting into 42.33% WL, 9.73% SG, 419.33 mg/100 g dry matter AA and 6.01 mg/g dry matter OA. Quadratic models were found to fit well (R², 0.98, 0.89, 0.86 and 0.89) in describing the effect of variables on the responses studied. The regression coefficients of the second-order model and the probability of factors influenced the responses at linear, quadratic and interactive level.