Experimental and Theoretical Investigation of Mass Transfer during Leaching of Starch and Protein from Potato

Abstract

In this article, mass transfer during leaching of starch and protein from potato using water as the solvent was investigated. Leaching experiments were carried out by immersion of slab-shaped potato samples in distilled water at 30°C, 45°C, and 55°C, and amounts of starch and protein loss, and moisture gain by the samples were evaluated at different process duration times. A two-parameter model was proposed for prediction of the kinetics of mass transfer and also estimation of the final equilibrium values of solutes loss and moisture gain by the samples. Effective diffusivities of solutes and moisture were estimated by fitting the experimental data of solute loss and moisture gain to the analytical solution of Fick's second law of diffusion. Moisture, starch, and protein distributions into the potatoes were predicted as a function of time and location into the samples. Mean relative errors (MREs) between the predicted concentrations by the proposed models and experimental data were in the ranges of 0.037–0.104 and 0.063–0.205 for the two-parameter model and the analytical solution, respectively. Estimated equilibrium solute losses were between 0.922 and 1.549 (g/100 g fresh fruit) for protein and between 10.893 and 11.848 (g/100 g fresh fruit) for starch. Also equilibrium water gain (WG) was in the range of 35.842–46.296 (g/100 g fresh fruit). Effective diffusivities were estimated in the range of 1.334–1.817 × 10−10 m2/s for moisture and 1.070–1.893 × 10−10 m2/s for solutes.