DIFFUSION OF WATER IN CEREAL-BREAD TYPE FOOD FIBERS

A study involving water vapor diffusion in cereal-bread type dietary fibers was conducted. The experimental diffusivity data were derived from adsorption rate measurements for water vapor in wheat bran, oat fiber, corn bran, and rice fiber at 278, 288, 298 and 310 K, using a gravimetric method. The effective bulk diffusivities were determined by employing a Fickian model for isothermal diffusion, and were subsequently correlated by an Arrhenius type expression. Thermal effects on the rate measurements were evaluated through a nonisothermal analysis. The rate at which water diffused in different fibers followed the trend: rice > oat > corn > wheat. The effective diffusion coefficients of water in all fibers were in the range of 10(-3) -10(-4) cm(2)/s. As expected, all fiber samples were saturated faster at higher temperatures.