Milling quality of partially fissured rough rice

The factors that determine whether a fissured rough rice grain will break or survive the milling process were identified.;Two rice varieties, Lemont (long grain) and Rico (medium grain) were selected. Rough rice samples were equilibrated in an environmental chamber at a temperature of 23.9;Samples were inspected for fissured grains. Fissures were classified as partial, hairline and clear or full. Fissured grains were classified according to the number of fissures per kernel: one, two, three, more than three.;Samples were milled and head rice was inspected for fissured grains.;Linear regression equations expressing head rice recovery and broken rice content were developed.;The first indication that fissured grains survived milling occurred on the second cycle for both varieties. Percentage of fissured grains in rough rice was more than could be accounted for by broken rice. Broken rice content (milled rice basis) could be accurately estimated from the difference of percentage of fissured grains in rough rice and percentage of fissured grains in milled rice. Adjustments were allowed for broken rice not due to fissured grains. Visual judgment of whether a fissured grain will break during milling was not successful. The objective was to count fissured grains with a partial or hairline fissure and see if the total number of such grains approximated that of fissured grains that survived. In all instances, there were more fissured grains that survived than could be accounted for. The number of fissures per kernel was a better gauge of breakage susceptibility. An appreciable proportion of grains with a single fissure survived the milling process. Most grains with two or more fissures usually broke. Several cycles of exposure usually caused a fissured grain to break during milling.