Prediction of the Diffusion Process for Sodium Chloride in Root Vegetables and Evaluation of the Optimum Sodium Chloride Concentration

Abstract

The changes in NaCl concentration of 1-3 cm cubes of Japanese radish, carrot and potato soaked in a 0.8-2.0% brine solution at 20°C were calculated by a computer program. This program applied the finite difference method based on unsteady three-dimensional heat conduction and a diffusion analysis by Visual Basic (Microsoft). Each sample was prepared to obtain the optimum hardness. The sample was cooked from room temperature to boiling, after which the heat sauce was turned off and the sample was heated by residual heat. Each sample was soaked in a brine solution after attaining optimum hardness. A sensory evaluation for the strength of saltiness was carried out by using a 5-point rating scale (−2-+2). The soaking time was calculated to reach an average NaCl concentration of 0.6-0.9%. The results of the sensory evaluation showed an optimum average NaCl concentration of 0.7% when the concentration of the brine solution was 0.8-1.5% independent of the kind of vegetable and size of the sample. The optimum condition was not obtained when the brine solution concentration was 2.0%, because the NaCl concentration at the surface of the sample was too high. The optimum seasoning time was in the order of potato > carrot > Japanese radish.