Rehydration kinetics of high-pressure pretreated and osmotically dehydrated pineapple

Rehydration kinetics of high-pressure pretreated (100, 300, and 500 MPa for 10 min) and osmotically dehydrated pineapple (Ananas comsus) cubes (2 x 2 x 1 cm) were studied at different temperatures (5, 25, and 35 degrees C), and compared with ordinary osmotically dehydrated samples. The effective diffusion coefficients for water and solute were determined, assuming the rehydration process to be governed by Fickian diffusion. Diffusion coefficients for water absorption into the tissue as well as for solute diffusion out of the tissue were found to be lower in the samples subjected to high-pressure treatment. Further, the diffusion coefficients decreased with increase in treatment pressure. A possible explanation for the observed decrease in diffusion coefficients can be attributed to the permeabilization of cell membranes, the release of cellular components, and structural changes of the cell materials. The diffusion coefficients were correlated with rehydration temperature (T) and treatment pressure (P) by an Eq. of the form D = A exp[-(B.P + C/T)], where A, B, and C are constants.