October 22/Science Letter -- "Casein micelles were loaded with iron to create a dispersible delivery format for insoluble iron by exposing milk at chilled temperatures to a high concentration of soluble iron (up to 20 mmol kg(-1) ferrous and ferric chloride). The loading was maximised by applying a pH-cycle to the fortified milk by means of carbonation," scientists in Montpellier, France, report.
"Upon acidification of fortified milk, no release of iron was observed, except at the highest concentration. Changes in the buffering capacity as a function of pH confirmed the formation of colloidal iron phosphates. Overall, most properties of the micelles did not change: hydration, protein distribution between soluble and colloidal phase remained constant, but zeta potential decreased slightly and curd formation upon renneting became much slower. The renneting behavior could be improved by carbonation or storage at 30 A degrees C for a day. Iron-fortified milk samples were stable under heating, except when fortification was achieved by means of 20 mmol kg(-1) ferric chloride," wrote S. Raouche and colleagues, University of Montpellier.
The researchers concluded, "The most obvious difference of iron-fortified milk is its appearance: samples fortified with ferrous chloride were darker than control, whereas samples fortified with ferric chloride were more red/yellow."
Raouche and colleagues published their study in European Food Research and Technology ("Casein Micelles as a Vehicle for Iron Fortification of Foods." European Food Research and Technology, 2009;229(6):929-935).
For additional information, contact S. Marchesseau, University of Montpellier, IATE, UMR 1208, Pl E Bataillon, Cc 023, F-34095 Montpellier 5, France.
From the October 26, 2009, Prepared Foods E-dition