Preparation, characterization and enhancement of intestinal iron absorption activity of β-casein phosphopeptides-iron chelate

In this study, the β-casein phosphopeptides (β-CPPs) was enzymatically prepared from β-casein, followed by the preparation of β-casein phosphopeptides-iron chelate (β-CPPs-Fe). The results of Ultraviolet–Visible absorption spectroscopy (UV) and Fourier transform infrared spectroscopy (FTIR) indicated that the -COOH, O-H, N-H, and P-O-C of the β-CPPs may chelate with iron during the chelation. The amino acids involved in the chelation process were predominantly pSer, Tyr, Trp, and Phe. The scanning electron microscopy showed that due to β-CPPs combined with iron, the microsurface of β-CPPs-Fe displayed a predominantly loose porous structure. After the chelation with iron, the particle size distribution and zeta potential of β-CPPs-Fe increased. In vitro simulated gastrointestinal digestion revealed that β-CPPs-Fe demonstrated a significant increase in iron solubility compared to FeSO₄·7 H₂O (p < 0.05). At the endpoint of transport (180 min) in Caco-2 intestinal epithelial cell model, the amount of transferred iron for β-CPPs and β-CPPs-Fe increased by 30 % and 57 %, respectively, compared to the control group. Both β-CPPs and β-CPPs-Fe exhibited favorable effects on enhancing iron absorption, with the promotional impact of β-CPPs-Fe being notably more pronounced. The experimental findings establish a theoretical foundation for the industrial implementation of iron-fortified food products.