Drying and Polishing of Fortified Rice Kernels

Rice is a staple food globally, but it undergoes significant nutrient loss during processing, which includes soaking, steaming, drying, and polishing. Polishing removes the micronutrient-rich outer coat, resulting in lower nutritional content essential for human health. Rice fortification is a beneficial strategy to restore and enhance its micronutrient profile. Fortification techniques, including soaking, coating, spraying, extrusion, and germination, ensure nutrient incorporation into fortified rice kernels (FRK). Drying is a crucial step in FRK manufacturing, designed to remove excess moisture while minimizing nutrient degradation. Various drying methods such as sun drying, hot air drying, freeze drying, microwave drying, microwave-assisted hot air drying, and fluidized bed drying impact drying kinetics, micronutrient retention, and structural integrity of the FRK. Advanced drying techniques are preferable as they reduce heat-sensitive nutrient loss while maintaining the rice quality. Polishing is another key post-harvest process involving the removal of the oil-rich bran layer, improving rice’s functional properties such as water absorption index (WAI), water solubility index (WSI), digestibility, reducing rancidity induced by oil-rich bran layer, heavy metal residue, and enhancing the shelf life of the rice kernel. However, polishing can lead to nutrient depletion, which fortification compensates for, ensuring that the rice remains nutritionally adequate. Optimizing drying and polishing conditions, including drying time, air velocity, and degree of polishing, enhances the quality of FRK. Properly fortified rice addresses malnutrition, particularly deficiencies such as iron deficiency anemia.