Oil absorption reduction of eggplant slices during deep fat frying by applying osmotic dehydration pretreatment

Background and Objectives: A fairly large amount of oil is absorbed to the food during deep frying. The aim of this study was to reduce the oil absorption of eggplant slices during frying by using osmotic dehydration pretreatment. Materials and Methods: Using maltodextrin (0, 20, 40% w/v) and sodium chloride (salt, 0, 10, 20% w/v), the effect of osmotic dehydration on different properties of eggplant slices (2 × 2 × 2 cm) was investigated. Osmotic dehydration was carried out in a factorial arrangement with two factors: maltodextrin and salt concentrations at constant time (90 min) and temperature (30 °C). The effect of osmotic dehydration on the moisture loss, solid gain, osmotic performance ratio (PR) and shrinkage of the samples after osmotic process, as well as the oil absorption, texture, color, and sensory properties of eggplant slices after frying was investigated. Results: Increasing the concentration of maltodextrin (0 to 20%) and salt (0 to 10%) in osmotic solution increased the dehydration, adsorption of solids and performance ratio in the eggplant slices significantly. The highest moisture loss (37%) and nearly the least oil absorption (9%) were related to the 20% salt-40% maltodextrin treatment. The highest oil absorption (37.3%) was observed in the control sample. The lowest shrinkage after frying (15.6%) was attributed to the 10% salt - 40% malt treatment. Conclusion: Due to the low absorption of oil and almost the highest sensory scores, the best treatment for osmotic dehydration and frying of eggplant is 40% maltodextrin - 10% salt with 29% reduction in oil absorption.