Fabrication of iron loaded whey protein isolate/gum Arabic nanoparticles and its adsorption activity on oil-water interface

Design and fabrication of iron fortifier is very essential in the prevention or improvement of iron-deficiency anemia in food industry. In this study whey protein isolate (WPI) and gum arabic (GA) loaded with ferric ions was expected to be self-assembled to form stable nanoparticles by heating at 85 degrees C for 15 min at pH 4.0. It is illustrated that WPI/GA(Fe3+) nanoparticles were more uniformly dispersed in comparison with the easily aggregative GA(Fe3+) complex. The tightly binding of ferric ions was confirmed by FTIR and XPS. During formation of WPI/GA(Fe3+) aggregates induced by heating, the disulfide bond was formed and the surface hydrophobicity was significantly enhanced. The ferric ions release rate of WPI/GA(Fe3+) nanoparticles was significantly slower than that of GA(Fe3+) complex in simulated gastric juice due to the fact that the assembled structure exhibited a delayed effect on the hydrolysis of peptides catalyzed by pepsin during its internal diffusion into nanoparticles. WPI/GA(Fe3+) nanoparticles contributed to a good adsorption activity on oil-water interface between WPI and GA(Fe3+) complex because of its high steric hindrance. The decrease of interfacial tension with sequential adsorption demonstrated that WPI/GA(Fe3+) nanoparticles could be electrostatically adsorbed onto positively charged sodium caseinate interface, or co-adsorbed onto non-ionic Tween 80 interface, forming a more stable interface with higher steric hindrance and lower interfacial energy. Thus, the self-assembled WPI/GA(Fe3+) nanoparticles would have great potential in the application for iron fortification especially in food emulsion system.

Automated summary

In this study, whey protein isolate (WPI) and gum arabic (GA) loaded with ferric ions were self-assembled into stable nanoparticles by heating at high temperature and low pH, exhibiting slower release of iron ions in simulated gastric juice. These nanoparticles showed good iron fortification potential in food emulsion systems.