Relative Impact of Kernel Thickness and Moisture Content on Rice Fissuring during Drying

Abstract

Abstract.Individual kernel thickness and moisture content (MC) vary within rice panicles. These variations affect the drying characteristics of rice kernels and consequently, the milling yield. This study utilized an X-ray system augmented with an in-situ rice drying apparatus that enabled fissure detection in rough rice kernels during drying and tempering. Rough rice kernels of two long-grain cultivars (Roy J and CL XL745), each at two MC levels (20% and 16%, w.b.), were fractionated into three thickness fractions (thin <1.98 mm, medium 1.98 - 2.03 mm, and thick >2.03 mm). Kernels from each of the 12 sub-lots were dried and tempered under controlled air conditions. Fissured kernel percentages (FKP) were determined from X-ray images taken before, during, and after drying and tempering. Kernel thickness and MC both affected moisture desorption fissuring. Generally, as kernel thickness increased, the FKP increased for high-MC lots. In regards to MC, high-MC lots were more prone to fissuring than the low-MC lots. Overall, these findings highlight the role of kernel properties on fissuring during drying. Keywords: Kernel fissuring, Kernel thickness, Moisture content, Rice drying, X-ray imaging.