Apparent Diffusion Coefficient of Sodum Chloride in Cubical Agar Gel

Abstract

Cubes of 2% agar gel, with side lengths (2L) of 1, 2, 3, 5, 7 and 10cm, were soaked in a 0.1 M sodium chloride solution at 25°C. After soaking for 0-75 hr (f), the amounts of sodium chloride and water in the gel were measured, and the mean concentration of the sodium chloride in the gel cube was calculated. The ratio of the mean concentration to the boundary concentration (C_r) depended on the value of t/L². The value for the apparent diffusion coefficient (D_app), which was yielded by substituting the values of t/L² and Cr into the solution of the diffusion equation, depended on t/L² and C_r, and reached the maximum value (1.03 × 10^-5 cm²/sec) at about C_r = 0.6. The relationship between C_r and D_appt/L² which is shown in this paper, can be applied to the diffusion of any substance in various food materials other than agar gels or sodium chloride.