รายงานการวิจัย -- มหาวิทยาลัยเทคโนโลยีราชมงคลพระนคร, 2553During the rice processing, the possible situations of rice kernel cracking and breakage are commonly occurred and these consequences cause a low marketing price. According to this issue, the real-time observation and together with the knowledge base of mechanical properties should be essentially helpful in detection of these defect observations. The objective of this work was established to study the mechanical stress-strain properties of rice kernels via our in-house pneumatic system design. We found that stress-strain of RD6, RD15, Phitsanulok 2 and Khao Dawk Mali 105 were greater than Khao'Yipun DOAI with moisture content of 20% w.b. These results tentatively indicated the mechanical stress-strains occurred were from the difference of rice shapes. Moreover, we could recognize that the characteristics of these various shapes significantly followed the scaling law of the relation between strain and time. We also found that the breaking force was different value for rice varieties. This parameter obtained can be such a high potential approach that can be used for further developing in the quantitative classification of rice varieties.Rajamangala University of Technology Phra Nakho