Drying modeling, cooking characteristics, pasting properties, and crystallinity of fortified rice kernels

Fortified rice kernels (FRK) are vitamin-mineral fortified extruded analogue resembling raw rice. Drying is an important operation that needs to be controlled for the good quality of FRK. The present study investigated the effect of drying air temperature (40-70 degrees C) and velocity (0.5 and 1.0 m/s) on the drying kinetics, cooking characteristics, pasting properties, and crystallinity of FRK. The drying modeling suggested the best suitability of Page, Diffusion, and Midilli-Kucuk models with R-2 > 0.9997, RMSE < 0.0049, and chi(2) < 2.940 x 10(-5). The effective moisture diffusivity of FRK varied from 6.653 x 10(-9) to 11.014 x 10(-9) m(2)/ s, whereas the activation energies were 15.32 and 15.47 kJ/mol at 0.5 and 1.0 m/s, respectively. The FRK dried at 40 degrees C showed 28.56 +/- 1.24% solid loss and 2.66 +/- 0.42 WAR while FRK dried at 50-70 degrees C disintegrated during the cooking. The increase in temperature did not show any significant change in the pasting properties and crystallinity of FRK. Practical applications Improper drying of FRK causes quality deterioration in terms of fissure formation and increased cooking losses. The results suggested that the low-temperature drying of FRK is useful compared to a high temperature to improve the cooking characteristics. Moreover, the drying modeling will help to obtain suitable drying conditions for FRK and design the continuous drying system at a commercial scale.