WATER ABSORPTION CHARACTERISTICS OF WHEAT AND BARLEY DURING SOAKING

Abstract

Water absorption characteristics of wheat and barley during soaking were measured at five temperatures rangingfrom 10.C to 50.C. From the water absorption characteristic curves, it was determined that water absorption of wheat andbarley was in the second falling rate period. Using the measured data, a nonlinear least squares method was applied to anapproximate solution of the diffusion equation MR = B1 exp(Kt). Values of parameter B1 for the diffusion model wereestimated to be about 0.6 for wheat and about 0.8 for barley. Therefore, the measured data were fitted to the exact solutionfor the sphere diffusion model for wheat and for the infinite plane sheet diffusion model for barley by a nonlinear least squaresmethod. The measured results agreed well with the calculated results. The values determined for the diffusion coefficients were1.1 . 1012 to 1.0 . 1011 (m2/s) for wheat and 3.5 . 1012 to 3.9 . 1011 (m2/s) for barley. An Arrheniustype equation wasused to relate the diffusion coefficient of wheat and barley to temperature (T), and the energy of activation (E) for wheat andbarley was estimated. The values determined were 44.0 kJ/mol for wheat and 45.9 kJ/mol for barley.