6533b85afe1ef96bd12b9df9

RESEARCH PRODUCT

Peroxydation des lipides émulsionnés et transfert d'ions fer à l'interface huile / eau stabilisée par des protéines de lait : influence des résidus phosphates et de la stabilité du chélate de fer

subject

description

Iron incorporated into food systems induces oxidation and precipitation. The consequences are a reduced bioavailability and a modification of other food flavor. The iron chelates such as Fe-bisglycinate and Fe-EDTA represent a possibility to avoid side effects, since the iron is protected. The inertety of Fe bisglycinate and NaFe EDTA for lipid peroxidation has been verified in oil-in-water emulsion models stabilized by sodium caseinate or by β lactoglobulin through the following studies: i/ increase of primary and secondary products of oxidation, ii/ change of the properties of the oil/water interface (tension and interfacial rheology), iii/ the stability of the chelate iron (Fe-bisglycinate) in the aqueous phase with β lactoglobulin at different pH (pH 2, 3.5 and 6.5). The oil/water interface stabilized by proteins with phosphate groups has induced peroxidation, which was not observed with proteins containing no phosphate residue. These results demonstrate also that the type of iron salts plays a crucial role in the oxidative stability of emulsions. The ability of the complex to retain iron ion and to avoid “free” ferrous ion is the first important factor to be controlled. The affinity of milk proteins to bind these free iron ions is the second factor that controls the transfer to oil/water interface. To sum up, the competition for iron ions between functional groups of protein and salt counter ions (glycinate, sulfate or EDTA) governs the oxidation state of the system in neutral conditions. In acidic medium, the oxidation is mainly governed by the stability of the complex and the possibility to free iron in bulk.