Correlation between head rice yield and specific mechanical property differences between dorsal side and ventral side of rice kernels

• Mechanical properties of rice kernels on dorsal side were different with ventral side.
• Breaking force and strength on ventral side were lower than those on dorsal side.
• Rice fissure appearing originally on ventral side was related to breaking strength.
• Milling quality was related to the breaking force and strength difference.

Three-point bending tests on both ventral and dorsal sides of brown rice kernels were conducted to determine relationship between head rice yield and mechanical properties. Kernel breaking force on ventral side was lower than that on dorsal side. The same result was also revealed in the breaking strength and the elastics modulus. Frequency distribution of the kernel-to-kernel breaking force of ventral side was significantly different from that of the dorsal side. The breaking force difference between the ventral side and the dorsal side increased with increase in the average breaking force. It was found that rice milling quality index not only was related linearly with the breaking force on both the ventral and the dorsal sides, but also related to the breaking strength difference between the two sides. The head rice yield increased with the increase in the break force difference between the ventral side and the dorsal side.