Structural properties and solute transfer relationships during sucrose and stevia osmotic dehydration of apple

The objective of this research was determined the structural changes in plant tissue during osmotic dehydration (OD) of apple in stevia and sucrose aqueous solutions. Macro and microstructural properties at different thicknesses of the sample were determined. For the study of structural properties, samples were cut in five slices at different thicknesses (0.5, 2, 4, 7, 10 mm in z direction) from the surface to the sample center. Anhydrous real density, volume and microscopy images in sample slices were determined and its relationship with the transfer of water and solutes inside the tissue were analyzed. Anhydrous real density in food considering the solids density in the sample was determined. Volume change as a function of moisture migration in the sample was evaluated. Apple samples were immersed into sucrose (30 and 50° Brix) and stevia (3 and 6%) osmotic solutions at 30 °C and 50 °C. The results showed an increase in the anhydrous real density in the area of greater loss of moisture and greater accumulation of solutes within the food. The volume increased in the thicknesses of the center of the sample where the moisture concentration was highest. The greatest alterations of the plant cell structure in the surface of the sample were observed.