Evaluating energy evolution and damage in rice kernels under compressive loadings

Rice processing is characterized by high energy consumption and significant product losses due to kernel mechanical damage in the form of fissuring and breakage. The dependance of grain properties on many inherent and external factors makes it difficult to predict material damage. For this reason, detailed descriptions of the mechanisms of rice kernel breakage is scarce. The aim of this study is to deepen the knowledge about the rice kernel breakage mechanism under single and repeated compressive loadings, as affected by moisture content and grain size. Based on the experimental results, the mechanism of kernel weakening as the evolution of damage and the strain energy were identified. For damage evolution, a power function was proposed to describe the change in damage with the number of loading cycles. It was found that the rice kernel breakage behavior, especially the damage accumulation, resulting breakage probability and fatigue life, is dependent on the moisture content and kernel thickness. The presented study shows that the breakage of rice kernels can be predicted from the change in strain energy. The results from this work can be applied to improvement in rice processing and can significantly contribute to the reduction of material and energy losses.