Mathematical Modelling in Osmotic Dehydration

Mass transfer parameters during osmotic dehydration of apple cv. Idared has been studied. The solution of Fick’s law for unsteady state mass transfer in rectangular configuration has been used to calculate the apparent diffusion coefficient of fructo-oligosaccharides (FOS) used as osmotic agent and water. Apple cubes were blanched and osmotically treated (0-60 min) in 60 % FOS solution at 40 °C, sample-to-solution ratio was 1:10. Total solid (TS) content of the samples was determined by gravimetric method, total soluble solid (TSS) content was measured by refractometer and FOS content was measured by polarimeter. The apparent diffusion coefficient of FOS and water were found to be of the order of 10 m/s. The model of the osmotic dehydration process is better for the water than for the FOS.