Osmotic dehydration of plums: analysis of operation conditions and determination of effective diffusion coefficients

Abstract

The objective of this work was to study osmotic dehydration kinetics of plums evaluating the influence of solution (type and concentration of solute, temperature, fruit/solution ratio) and process time on water loss, water content and solutes gain. Process analysis was performed experimentally by means of a set of 16 duplicate tests and numerically by mathematical modeling of the unsteady state mass transfer during osmotic dehydration. Aqueous solutions of glucose and sorbitol (40 and 60% w/w) were used for dehydrating plum pieces during 2 h at temperatures of 25 and 40ºC, and fruit/solution ratios of 1/4 and 1/10. For calculating effective diffusion coefficients the real shape of food pieces was considered using Finite Elements, working with the software COMSOL Multiphysics. Calculated diffusion coefficients are of the same order of those found in literature for regular shapes.