Fortified rice kernels (FRK) are a vitamin-mineral enriched extruded rice-shaped product blended with raw or parboiled rice in a 1:100 ratio to prepare fortified rice. In FRK manufacturing, drying is one of the essential steps that affect the quality of FRK. In the present study, the microwave technique was explored to dry FRK continuously at 180, 360, and 540 W and with the tempering (1, 2, and 3 min) at 180 W to evaluate the effects on the drying curves, color attributes, fissure formation, and cooking characteristics. Thin layer modeling suggested the Two-term exponential model (two parameters), diffusion model (three parameters), and Midilli Kucuk (four parameters) as the best models to predict moisture based on Akaike and Bayesian information criteria. The higher MWP (360 and 540 W) significantly lowered the L* and WI while increasing the a*, b*, and BI compared to 180 W, which was undesirable. Image processing showed fissures in all FRK samples; however, 1 min and 2 min tempering could somewhat restrict the fissure. The fissures caused higher solid losses and increased splitting of kernels during cooking. It can be concluded that the low MWP (< 180W) with appropriate tempering time can be used to dry FRK.
Supplementary information: The online version contains supplementary material available at 10.1007/s13197-023-05871-4.
Keywords: Color attributes; Cooking characteristics; Fissures; Fortified rice kernels; Microwave drying; Thin layer modeling.
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