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| مجله علوم کشاورزی ایران | ||
| Article 4, Volume 35, Issue 3 - Serial Number 1654, May 2004 PDF (312.38 K) | ||
| Abstract | ||
| In order to obtain some quality properties of wheat and rice kernels, which may be utilized for end–use property assessment, stress relaxation and uniaxial compression tests were conducted on wheat and rice kernels. In these tests, the effects of moisture content, strain level, and type of loading probe were investigated on mechanical properties of the two cereal grains. Along with measurement of mechanical parameters, stress relaxation tests were also carried out on wheat grains. Using these tests, the coefficients of two fitted polynomial equations were extracted from the curves as the indices of shape of curve. Based on the results, a linear relationship was defined relating the ratio of force decay, as a factor of stress relaxation curve, the force factor and c1 and d2 coefficients (of polynomial eq.’s), to the wheat hardness (an index of wheat milling quality). It was found that, wheat moisture content had a critical effect on the results. The effect of strain level on the results shows the considerable variations in mechanical properties, due to increase in strain level. According to the results of uniaxial compression tests and the strength properties of rice grain (extracted from the force – deformation curve), it was found that different varieties of rice can be classified based on measured parameters. In addition, use of two types of loading probes showed that for each kind of probe, a specific characteristic of grain tissue can be assessed. | ||
| Keywords | ||
| Compression test; Mechanical and rheological properties; rice; Stress relaxation; Wheat | ||
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