Dairy Science & Technology

, Volume 90, Issue 1, pp 87–98

Milk protein-iron complexes: Inhibition of lipid oxidation in an emulsion

  • Maya Sugiarto
  • Aiqian Ye
  • Michael W. Taylor
  • Harjinder Singh
Original Article

Abstract

Fortification of foods with iron is a common vehicle for delivering iron in required quantities to the consumer. However, many technological problems occur when food products are fortified with minerals, due mainly to the many reactions of minerals with other food components, e.g. fat oxidation. In the present study, the binding of iron (ferrous sulphate) to common milk protein products, sodium caseinate, whey protein isolate (WPI) and milk protein concentrate (MPC), to form protein-iron complexes was characterized by the amount of iron binding and the turbidity as functions of the iron concentration. In an emulsion containing linoleic acid, the oxidation activity of these protein-iron complexes was compared with that of the iron in its free state. The affinities of caseinate and MPC to bind iron were higher than that of WPI. These differences were attributed to the presence of clusters of phosphoserine residues in casein molecules, that are known to bind divalent cations strongly. Lipid oxidation experiments showed that the ability of iron to catalyse lipid oxidation was reduced significantly when iron was bound to protein compared with when it was in its free form. This suggests that the formation of milk protein-iron complexes could be a novel way of incorporating iron into food products with high bioavailability, good flavour and no solubility problems.

sodium caseinate whey protein isolate milk protein concentrate protein-iron complex emulsion oxidation 

Complexes protéines laitières-fer: inhibition de l’oxydation des lipides dans une émulsion

Résumé

La fortification en fer des aliments est utilisée couramment pour apporter aux consommateurs les quantités nécessaires en fer. Cependant, beaucoup de problèmes technologiques surviennent quand les produits alimentaires sont fortifiés avec des minéraux, principalement en raison de nombreuses réactions des minéraux avec les autres composants des aliments, par exemple l’oxydation de la matière grasse. Dans la présente étude, la liaison du fer (sulfate de fer) à des produits protéiques laitiers courants, caséinate de sodium, isolat de protéines de lactosérum et concentré de protéines laitières, pour former des complexes protéines-fer a été caractérisée par la quantité de fer lié et la turbidité en fonction de la concentration en fer. Dans une émulsion contenant de l’acide linoléique, l’activité oxydante de ces complexes protéines-fer a été comparée avec l’activité oxydante du fer à l’état libre. Les affinités du caséinate et du concentré de protéines laitières pour lier le fer étaient plus élevées que celle de l’isolat de protéines de lactosérum. Ces différences ont été attribuées à la présence dans les molécules de caséine d’amas de résidus phosphosérine qui sont connus pour lier fortement les cations divalents. Les essais d’oxydation des lipides ont montré que la capacité du fer à catalyser l’oxydation des lipides était significativement réduite quand le fer était lié aux protéines par rapport à celle obtenue quand le fer était à l’état libre. Ceci suggère que les complexes protéines laitières-fer pourraient devenir une nouvelle voie d’incorporation de fer dans les produits alimentaires.

caséinate de sodium isolat de protéines de lactosérum concentré de protéines laitières complexe protéine-fer oxydation dans les émulsions 

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Copyright information

© INRA, EDP Sciences 2009

Authors and Affiliations

  • Maya Sugiarto
    • 1
  • Aiqian Ye
    • 1
  • Michael W. Taylor
    • 1
  • Harjinder Singh
    • 1
  1. 1.Riddet InstituteMassey UniversityPalmerston NorthNew Zealand

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