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Rice fissuring and breakage under various drying and tempering conditions. M. J. JIMENEZ (1), A. G.
Cnossen (1), and T. J. Siebenmorgen (1). (1) Department of Food Science, University of Arkansas,
Fayetteville, AR 72704.
Rice breakage is a major quality and price devaluating factor. An
understanding of the effect of various drying and tempering treatments on fissure occurrence, and the
relation between fissure occurrence and breakage/head rice yield reduction will provide end-users, such as
cereal and cooked-rice product manufacturers, with information to optimize their processing operations.
The objectives for this study were: 1) determine the effect of various drying and tempering treatments on
fissure occurrence and 2) correlate fissure occurrence and head rice yield (HRY) to determine optimum
drying conditions and minimum tempering durations to maximize not only milling quality, but kernel
physical integrity as well. For the experiment three drying conditions were used, two above and one below
the glass transition temperature of the rice. Immediately after drying, the samples were separated into four
sub-samples and tempered for different durations. 200 brown rice kernels were randomly selected and
visually observed in a light box by one person, and the percent of fissured kernels determined. The results
showed that the percent of kernels having heavy fissures decreased with increasing tempering time.
However, some samples still showed many fissures after extended tempering, yet these samples had a high
HRY. This indicates that the tempering duration required for preventing kernel fissuring might be longer
than the tempering duration required for maintaining HRY. The percentage of light fissures slightly
increased with increasing tempering duration.
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