Whey protein-iron or zinc complexation decreases pro-oxidant activity of iron and increases iron and zinc bioavailability

Iron and zinc are involved in various functions and their deficiency may lead to several health issues. Fortification of these micronutrients in food is considered as the most effective approach to control deficiencies. Due to high reactivity, iron fortification involves various challenges with respect to oxidative stability and bioaccessibility. Whey protein (WP) serve as an inexpensive protein source and thus have been used in the preparation of protein-mineral (iron or zinc) complexes. In the present study, WP-mineral complexes were prepared and evaluated for their oxidative stability and bioavailability. Thiobarbituric acid value and induction period were measured as index for oxidative stability of lipids in linoleic acid emulsions. The pro-oxidant activity of iron when used as WP-iron complex was significantly reduced (P < 0.05) as compared to iron salt. In-vitro bioaccessibility studies revealed that bound proteins provided favourable conditions (i.e. insoluble at gastric and soluble at intestinal phase) to minerals. Moreover, the bioavailability of bound minerals in Caco-2 cells was significantly higher as compared to free minerals due the presence of digested whey proteins. Finally, catalytic activity of iron can be inhibited by complexation with WP and both WP-iron or zinc complexes could be used as organic fortificants in different food formulations.