Zusammenfassung
Moisture content patterns inside rice kernels are important in understanding
rice fissure formation, especially when glass transition effects
are considered. Unsteady and non-linear partial differential equations
were employed to describe two-dimensional temperature and moisture
distributions within a single rice kernel during drying and tempering
processes. Moisture content gradients (MCGs) inside the kernel were
examined. Results showed that the maximum MCG (MMCG) appeared in
the direction of the short axis. During the tempering process, moisture
content on the kernel surface had a much faster and greater change
than that at the kernel center. The intra-kernel MCG decreased considerably
during the first 40 min of tempering, after which it decreased slowly
to approach zero. A duration of about 40 min of tempering at 60�
C helped eliminate about 90% of the MCGs created inside the rice
kernel during drying, and this simulation result correlated favorably
with the published tempering data in the literature. The findings
from this study provided useful information for determining optimal
drying and tempering conditions of rice to enhance its milling quality.
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