Cereal Chem 38:540 - 547.  |  VIEW ARTICLE

Diffusion Coefficients of Water in Wheat Kernels.

L. Fan, D. S. Chung, and J. A. Shellenberger. Copyright 1961 by the American Association of Cereal Chemists, Inc. 

The diffusion coefficients of four varieties of wheat, Ponca (HRW) and Vernum (durum) wheats representing hard wheats and Seneca (SRW) and Brevor (SWW) wheats representing soft wheat, were measured under previously untried conditions (maximum temperature, 98.3 C. and maximum diffusion time, 8 hours). The theoretical treatment and the experimental techniques proposed by previous investigators were found to be valid under the conditions of the present investigation. The values of the diffusion coefficients ranged from 2.7 x 10[-8] cm[2]/sec (26.7 C.) to 245.6 x 10[-8] cm[2]/sec (98.3 C.) for Ponca wheat; 2.2 x 10[-8] cm[2]/sec (30 C.) to 75.2 x 10[-8] cm[2]/sec (86 C.) for Vernum wheat; 3.1 x 10[-8] cm[2]/sec (26.7 C.) to 140.9 x 10[-8] cm[2]/sec (98.3 C.) for Seneca wheat; and 2.7 x 10[-8] cm[2]/sec (30 C.) to 89.2 cm[2]/sec (86 C.) for Brevor wheat. The effective surface moisture content is independent of temperature, and the diffusion coefficients at temperatures below about 65 C. are practically independent of variety. The diffusion coefficients, and therefore the activation energies for diffusion, increase sharply above this temperature for four varieties of wheat.