DIFFUSION OF LOW-MOLECULAR COMPOUNDS IN FOOD MODEL SYSTEMS

The diffusion of NaCl and isopropanol was studied in a matrix of pure gel and one containing either carbohydrates, proteins or fat using the concentration-distance method. Concentrations of NaCl were measured b y conductivity, those of isopropanol by gas chromatography. Diffusion experiments have shown that the temperature dependence of the diffusio n coefficient is in accordance with an Arrhenius approach. Experimenta l and predicted diffusion coefficients did not agree satisfactorily wh en only models of mere obstruction were considered. Including the effe ct of hydration by values obtained from pure gels, experimental diffus ion coefficients range throughout between the calculated values of mer e obstruction and those obtained from a mathematical combination of ob struction and maximum hydration.