Ultrasonication-mediated multi-micronutrient fortification of polished rice to address micronutrient deficiencies

Ultrasonication-mediated multi-micronutrient fortification of polished rice was evaluated as a rapid and efficient strategy to enhance micronutrient loading and bioaccessibility. A one-pot process integrating soaking and sonication was optimized using response surface methodology (RSM), yielding optimal conditions of 2.73 min sonication, 5000 ppm fortificant concentration, and 240 min soaking time. Under these conditions, fortified rice showed markedly higher micronutrient concentrations than non-fortified controls, including iron (2802.42 ± 31.25 µg/g; ∼407-fold increase), zinc (813.05 ± 14.25 µg/g; ∼61-fold), thiamine (371.98 ± 13.92 µg/g; ∼413-fold), and folic acid (15.73 ± 0.32 µg/g; ∼8.4-fold). Simulated gastrointestinal digestion revealed nutrient-specific release patterns. Fortified rice retained high intestinal bioaccessibility of thiamine (78.93%), whereas the non-fortified sample showed complete loss at the intestinal phase. In contrast, folic acid exhibited reduced intestinal bioaccessibility (39.24%), indicating lower stability during digestion. Most minerals maintained measurable intestinal recovery, particularly iron (100.00%) and zinc (35.34%), indicating sustained solubility under simulated gastrointestinal conditions. Ultrasound treatment also altered physicochemical properties of the rice matrix. Rapid Visco Analyzer analysis showed significant reductions in peak viscosity (3463 → 1953 cP) and setback viscosity (3190 → 485 cP), indicating partial disruption of starch structure and reduced retrogradation.Texture profile analysis revealed decreased chewiness, while color measurements showed increased lightness in fortified samples. Overall, ultrasonication represents a scalable and energy-efficient approach for producing nutrient-dense rice kernels suitable for blending or food formulation, supporting scalable food fortification strategies to mitigate micronutrient deficiencies in rice-consuming populations.