Characterization and bioaccessibility of Fe²⁺-oat bran peptide chelate

Ferrous chelating peptides are ideal iron supplements due to their high bioavailability and low side effects. This study developed novel ferrous-chelating peptides from oat bran, a processing by-product, along with their microcapsules, providing a cost-effective approach for iron supplementation. The chelation mechanism was characterized, and the antioxidant activities were evaluated in vitro. Stable chelate formation was driven by Fe²⁺ coordination with functional groups from Glu, Asp, and Lys residues. The chelates exhibited strong antioxidant activity, with DPPH and OH radical scavenging capacities of 0.602 and 0.596 μmol Trolox eq/mg, respectively. Microencapsulation further increased the antioxidant capacity by 15-21 %. In vitro digestion revealed that the encapsulated chelates reduced Fe²⁺ release rates by 12.56 % in gastric fluid and 4.99 % in intestinal fluid, indicating improved bioavailability and reduced irritation. This work provides a practical strategy for developing functional iron supplements while promoting the valorization of food by-products.