RICE QUALITY AND PROCESSING Physical and Functional Characteristics of Broken Rice Kernels Created by Rapid Moisture Adsorption

Fissuring caused by rapid moisture adsorption generates appreciable amounts of broken kernels on subsequent milling, thereby reducing the economic value of rice. This study investigated how rapid moisture adsorption affects the extent of kernel fissuring in rice lots, as well as the physical and functional characteristics of broken kernels that result from milling such lots. Pure-line, long-grain cultivar Roy J was conditioned to 9% and 12% initial moisture content (IMC) levels, soaked in water at 30 °C (86 °F) for 2 h, gently re-dried to 12.0% moisture content (MC), and then milled to a surface lipid content of 0.4%. Milled rice yield, head rice yield, number-percentage of fissured kernels, and number of fissures/kernel were determined. Physical and functional properties of the broken kernels were also determined. Results showed that as IMC prior to rewetting decreased, the extent of fissuring increased, and hence, subsequent breakage increased. Additionally, with decreasing IMC, the number of fissures/kernel increased, leading to the generation of greater amounts of small brokens. The functional properties of the flour produced from small brokens were significantly different from the functional properties of the flour produced from large brokens. However, the functional properties of the flour produced from medium-sized brokens were not significantly different from those of the flour produced from either the small or large brokens.