Rice fissuring response to high drying and tempering temperatures

The objective of this study was to determine the effect of drying and tempering treatments on rice kernel fissuring at temperatures above and below the glass transition temperature (T-g). This information was correlated with head rice yield (HRY) data to determine optimum drying and tempering strategies to maximize milling quality and kernel physical integrity. Samples were dried under three different drying air conditions for various durations and then tempered for various durations at the temperature of the drying air. Results showed that the percentage of fissured kernels decreased with increasing tempering duration for typical drying durations (i.e., 3-5% points moisture content reduction in one pass). Some samples still had many fissured kernels after extended tempering, yet had a high HRY, equivalent to the control sample. This indicates that the tempering duration required for preventing kernel fissuring might be longer than the tempering duration required for maintaining a high HRY. (C) 2003 Elsevier Science Ltd. All rights reserved.