Coordination of Fe(II) to Eugenol to Engineer Self‐Assembled Emulsions by Rice Proteins for Iron Fortification

Fortification of ferrous irons (FeII ) is challenging due to fast oxidation. In this paper, we report that the coordination of FeII to eugenol can effectively inhibit the oxidation of FeII . The coordination was studied by UV-Vis spectra, nuclear magnetic resonance, Raman spectra, and so on, showing that it took less than 1 hr for FeII to be fully oxidized in water, whereas more than 10 days in eugenol. In addition, by gently mixing FeII coordinated eugenol and modified rice protein (MRP) solutions at ambient temperature, core-shell structures <200 nm were spontaneously formed, which can be utilized as protective and delivery systems for the organic ferrous irons. Based on the simulated digestion of MRPs, the FeII loaded emulsions may be delivered into intestinal tract beyond 2-hr oral administration. The results highlight the effectiveness of fortification of ferrous irons via polyphenol coordination combined with self-emulsification, advancing the future oral fortification of ferrous irons towards a feasible approach. PRACTICAL APPLICATION: The coordination of metal ions with food polyphenols can provide the functional food with excellent redox stability. The FeII loaded eugenol emulsified by MRPs can be used as a straightforward protocol for the development of functional ingredients for iron fortification in food industry.