Sonochemistry of rice: Its textural effects and postharvest iron fortification

• Main Author: Bonto, Aldrin P.
• Format: text
• Language: English
• Published: Animo Repository 2021
• Subjects: Sonochemistry; Rice; Rice > Milling; Sonication; Fortification; Chemistry
• Online Access: https://animorepository.dlsu.edu.ph/etdd_chem/1; https://animorepository.dlsu.edu.ph/cgi/viewcontent.cgi?article=1001&context=etdd_chem
• Institution: De La Salle University

Nutritional iron content in milled rice is generally lost as a result of milling due to the removal of the aleurone layer. Iron fortification in milled rice is recommended to regain the lost nutrients and address the malnutrition issues. This work investigates the effect of sonication on brown and milled rice grains of both waxy and non-waxy varieties. We report herein the microstructural analysis of uncooked rice kernels under sonication and its effect on the textural properties. X-ray computed tomography results showed the formation of microporous surfaces and the creation of cracks and fissures. Sonication increased the % porosity of the rice samples allowing for easy penetration of water during the cooking process and promotes softer texture. Moreover, this work also investigates the uptake of iron and its diffusion into the kernel on ultrasonic-treated milled rice. Rice samples were subjected to ultrasonic waves resulting in the formation of microporous surfaces and the creation of fissures in the milled rice. Sonication followed by soaking in aqueous iron solution resulted in the uptake of 321 ± 13.43 mg of iron per kg of rice, a 28-fold increase compared to the endogenous iron content of milled rice with retention of 82.9% upon washing and cooking. Cross-section mapping (μ-XRF) of the concentration of the iron fortificant into the uncooked grains showed inward diffusion at different rates reaching into the kernel core. Results also show that sonication decreased the amount of water-soluble phosphorus in rice suggesting the removal of potentially anti-nutrient phytic acid. Textural analysis of ultrasonic-treated iron-fortified rice premix revealed favorable properties that can be advantageous for its consumer acceptability. Moreover, the effect of sonication in brown rice resulted in the decrease in endogenous iron and phosphorus contents but increased its capacity for iron uptake through fortification when sonicated rice is soaked in the mineral solution.