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Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  Paper number  036138,  2003 ASAE Annual Meeting . (doi: 10.13031/2013.15414)
Authors:   Qingling Zhang, Wade Yang, Zhenhua Sun
Keywords:   rice, mechanical property, drying, fissuring, stress crack, three-point bending, modulus of elasticity, bending strength, fracture energy

Mechanical properties including the apparent modulus of elasticity, bending strength, and fracture energy of the brown rice kernels that were thin-layer dried at 60oC and 17% relative humidity for 0, 10, 30, 50, 70, 90 and 120 min were measured by three-point bending tests after rice kernels were cooled down to room temperature. The apparent modulus of elasticity, bending strength, and fracture energy of the sound brown rice kernels increased with increased drying durations, while these properties of the fissured kernels were found to be much smaller in magnitude than those of the sound kernels, especially for the bending strength and fracture energy. This explains why fissured kernels are much easier to break during milling. The finding that the bending strength and the fracture energy of the fissured brown rice kernels decreased with increased drying durations indicated that fissures were either created or propagated during the drying process, which weakened the fissured kernels as drying proceeded. Mechanical properties measured on the sound kernels at different drying durations would not be affected by the loss of the sound kernels to fissured or broken kernels. The sound kernels collected at different drying durations had a similar thickness distribution.

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