The osmotic dehydration of apricot and its effect on drying

ABSTRACTMaster ThesisTHE OSMOTIC DEHYDRATION OF APRICOT AND ITS EFFECT ON DRYINGAyşe İSPİRFırat UniversityGraduate School of Natural and Applied SciencesDepartment of Chemical Engineering2006, Sayfa: 104In this study, the drying and the osmotic dehydration of apricot were investigated. For thisaim, different osmotic mediums were prepared. The effect of various parameters on the osmoticdehydration such as: kind osmotic matter, the concentration of solution, temperature, the ratio ofsample/solution, time, the geometry of sample, pre-treatment, shaking and continuous-discontinuous procedure was investigated. The effective diffusivity and mass transfer coefficient ofwater loss and solid gain and equilibrium distribution coefficients during osmotic dehydration ofapricot were calculated. Then, the effects of procedure parameters on these coefficients weremodeled by using non-linear regression. In addition, the shrinkage during osmotic dehydration wasinvestigated.The osmotically dehydrated apricots were dried at constant temperature at 75 oC. Thedrying kinetics was investigated and the effective diffusion coefficients during drying werecalculated for the whole parameters.The experimental results showed that the continuous method was better than discontinuousmethods; the effect of shaking was not valuable. The water loss and solid gain were increased byincreasing solution concentration, temperature and procedure time, decreasing the ratio ofsample/solution, and the reduction of the geometry of the sample. The application of pretreatmentdecreased the water loss and solid gain.The shrinkage results showed that the changes in volume, diameter, length and density ofapricot with the reducing moisture content was smaller than conventional drying.Key Words: Apricot, osmotic dehydration, drying, shrinkage, kinetic, modelingI