A novel iron fortifier prepared through quinoa protein peptides hydrolyzed with different proteases

Iron deficiency is a widespread global issue that leads to nutritional disorders and iron deficiency anemia (IDA). In this study, quinoa protein peptide (QPP) was selected to design a novel iron supplement, quinoa protein peptide‑iron chelate (QPP-Fe). Notably, QPP with a molecular weight of <2000 Da, prepared using Alcalase, exhibited the highest iron chelation ratio of 79.2 ± 0.36 mg/g. Furthermore, FTIR, UV-Vis, CD, and fluorescence spectroscopy results indicated that the addition of Fe²⁺ significantly altered the secondary structure of QPP. This alteration was primarily attributed to the interaction of Fe²⁺ with carboxyl, amino, and imidazole groups. Moreover, we observed that the QPP-Fe form compact spherical structures, leading to reduced and much more uniform particle sizes. The molecular docking results revealed that Fe²⁺ formed ligand bonds with Glu, His, Ala, and Gly through electrostatic interactions. Then a pocket structure that wrapped Fe²⁺ around the peptide was formed, which changed the peptide from a free and disordered state to a more stable state. These results can provide a reference for the development of iron-fortified functional foods.