Head Rice Yield Reduction Rates Caused by Moisture Adsorption

An empirical rate equation was developed to predict head rice yield reduction for rough rice exposed to moisture adsorptive conditions. Time of exposure, initial moisture content, and relative humidity were significant to the reductions in head rice yield caused by moisture adsorption. An equation used to predict the number of kernels which fissured upon exposure to various environments was modified and evaluated for use in describing head rice yield reductions. A decrease in head rice yield of greater than 20 percentage points was found in the lowest initial moisture content rice samples (9% wet basis) subjected to the highest relative humidity of 90%. Lower reductions in head rice yield were found in the higher initial moisture content samples and at the lower relative humidity of 70%. Most of the damage to the kernels occurred within the first 24 hours of exposure to the humid air.