Moisture
absorption of long grain rice and absorption induced stresses were studied using axisymmetrical finite element method.
The rough rice kernel was treated as a 3 layer ellipsoid, which consists of hull, bran, and endosperm. Moisture ( M ) diffusion and temperature ( T ) conduction in the kernel were analyzed first. M and T in the kernel were studied at different rice initial moisture content ( M 0 ) and air relative moisture content ( R H ) levels. With the obtained M and T data under each level, the viscoelastic stresses caused by
absorption in the endosperm of the kernel were computed. The material of the endosperm was considered as a linear viscoelastic. The distribution of axial stress on mid section of endosperm and the change of the stresses during absorption were obtained. The peak tensional stress was found at center of the kernel, which is consistent with the observation of fissuring originated from the center. As its importance for fissuring control, the peak stress was studied for different M 0 and R H , and a family of contour lines of the peak stress were drawn in M 0R H plane which may be used to estimate the possibility of rice grain fissuring in different absorption conditions. The results obtained in this paper lay the foundation for improving drying quality of rice.