A ferric oxyhydroxide nanoparticle (FeONP)-mediated mechanism has been suggested recently for anchovy (Engraulis japonicus) meat (AM) enhancement of non-heme iron absorption. The current paper fractionates AM biomass into protein (70.67%), lipid (20.98%), and carbohydrate (i.e., glycogen and mucopolysaccharide, 1.07%) and evaluates their capacities in templating the formation of FeONPs under simulated gastrointestinal digestion. Results show that their iron-loading capacities (mg/g) follow the ascending order glycogen (2.43 ± 0.65), protein (20.16 ± 0.56), AM (28.19 ± 0.86), lipid (33.60 ± 1.12), and mucopolysaccharide (541.33 ± 32.33). Protein and lipid act in synergy to contribute the overwhelming majority (about 90%) of AM's iron-loading capacity. l-α-Phosphatidylcholine and l-α-lysophosphatidylcholine are the predominant iron-loading fractions in the lipid digest. Dynamic light scattering and transmission electron microscopy exhibit coating of inorganic cores of the formed FeONPs with peptides or phospholipid-based mixed micelles. Overall, protein and phospholipid are key players in the nanoparticle-mediated "meat factor" mechanism.
Keywords: anchovy meat; ferric oxyhydroxide nanoparticle; gastrointestinal digestion; mixed micelle; non-heme iron; peptide; phospholipid.