Studies on the strain and the cracking of rice kernels during drying (I)

particularly a method of calculation of cross sectional area and the modulus of elasticity of brown rice by compression test

Abstract

The authers supposed that the crak of rice was produced by the strain caused by variation in moisture content at some parts of the rice kernels during drying. In this study, we measured the modulus of elasticity of brown rice by compression test, the shape and the cross sectional area of the brown rice from the X-ray film. For experiments, we selected whole kernels of brown rice (Tosan No. 38), at 14.9, 16.3, 20.5, percent moisture content(W. B.).
The results obtained were as follows;
1. The average cross sectional area of compression test specimens were calculated by Sympsons equation.
2. In the compression test, the stress for the brown rice of low moisture content was larger than that of high moisture content at same strain.
3. The modulus of elasticity of brown rice determined from the linear portion of the stress-strain curve, were found to be 65.7, 52.0, 44.3 and 28.4kg/mm², at respectively 14.9, 16.3, 20.5 and 22.2 percent moisture cotent (W. B.).