Influence of osmotic agent on the physiochemical composition and drying kinetics of Gala apples

Abstract

Osmotic pre-treatment has been used in the drying of fruit to improve their quality. The aim of this work was to evaluate the effect of different osmotic agents (sucrose and maltodextrin) on the physicochemical composition and convection drying kinetics of Gala variety apples (Malus domestica, Borkh). Apple slices, cut in disks, were osmotically concentrated in sucrose and malt dextrin solutions for six hours, after that it was drained and dehydrated at 70 ºC in a PARDAL commercial tray dryer, until 10% moisture content. The osmotic treatment with sucrose, notably that with sucrose, promoted an increase in reducing sugars, decrease in titratable acidity and a greater process yield. In relation to the drying kinetics, osmosis promoted a reduction in the drying rate, there being  no remarkable differences between the two types of solute used.