Preparation of novel chitosan iron microgel beads for fortification applications

The aim of this research was to develop a range of novel chitosan iron microgel beads, and test their suitability for use as an iron fortification strategy to be incorporated into a foodstuff. Chitosan microgels were prepared by direct gelation in iron solutions, with final encapsulation levels of between 50 and 70 mg/g dried bead. The optimal route of manufacture was using an ammonium ferric citrate solution, in which the iron was found to strongly bind to the resultant chitosan matrix, with minimal release and no associated pH change in a range of aqueous media, including a model food system of simulated milk ultrafiltrate. The iron was only released from these beads in simulated fasted state gastric fluid of pH 1.2, with a sustained release over 2 h. However, in simulated fed state gastric conditions (pH 3) the beads provided a desired gastric bypass of the iron. These ammonium ferric citrate beads were used to fortify a model infant formula and results from the thiobarbituric test showed that the chitosan iron gel beads reduced lipid oxidation significantly, compared to when the same concentration of iron was included in the form of conventional iron salt.