Effect of solute on osmotic dehydration and rehydration of vacuum impregnated apple cylinders (cv. Granny Smith)

Apple (cv. Granny Smith) cylinders (10 mm diameter, 10 mm height) were vacuum impregnated, osmodehydrated and rehydrated using solutions of glucose, sucrose and trehalose. For dehydration solutions aw was 0.96, whereas for rehydration aw was 0.99. Throughout dehydration, total and component mass variations and sample shrinkage were quantified. Peleg’s equation was used to model changes in water and solute contents. The kind of solute affected mass transfer rate and the glucose solution showed the lowest kinetics. Over rehydration time (up to 10 h) water and solute fluxes and solute concentration of the sample liquid phase were quantified and modelled by applying Peleg’s equation. Samples treated with trehalose rehydrated to a greater extent, and showed better liquid phase retention which demonstrates the protecting role of this sugar on cell membranes.