Osmotic dehydration of kiwifruit (Actinidia Chinensis):: Fluxes and mass transfer kinetics

Pulsed-Vacuum-Osmotic-Dehydration of kiwifruit (Actinidia chinensis) was studied using two kinds of osmotic solution: sucrose (65 Brix) and concentrated grape juice (63 Brix), three temperatures (25, 35 and 45C) and four vacuum pulse times (0, 5 10 and 15 min). Experimental results enabled the mass transfer kinetics for water and solutes to be studied (compositional changes of the liquid fraction and changes in the liquid fraction/solid matrix ratio). The impregnation of samples, because of the vacuum pulse, was higher when concentrated grape juice was used as the osmotic solution, probably due to its lower viscosity. The effective diffusivity (D-e) was obtained for each experimental condition and the results show higher diffusivities for vacuum-pulsed treatments, although differences between treatments with different vacuum-guise time could not be observed. D-e values were slightly greater for treatments with concentrated grape juice. The activation energies (E-a) were obtained by fitting the data to the Arrhenius equation.