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“The fortification of food products with colloidal nanoscale particles is an important field of research in the food industry, as the addition selleck kinase inhibitor of such particles can be an efficient, simple and cost-effective way to fight mineral deficiencies both in developed and third world countries (Acosta, 2009 and Velikov and Pelan, 2008). Of the essential minerals,

iron is the most problematic to add to foodstuffs, mainly due to the reactivity of ‘free’ iron ions (from, for instance, iron sulphate) with various components of the products such as the polyphenols that are abundant in plant-based foodstuffs (Mellican, Li, Mehansho, & Nielsen, 2003). Polyphenols strongly chelate cations and the complexes with iron have intense and persistent colours (Hider et al., 2001, Mellican et al., 2003 and Van Acker et al., 1996), as illustrated by the fact that gallotannic acid (a polyphenol from gallnuts) GSI-IX combined with Fe2+ has been used abundantly as a black ink for about 2000 years (De Feber, Havermans, & Defize, 2000). In this work, various systems of iron-containing nanoscale particles were prepared, with the intention of

reducing the reactivity of this iron, with respect to the free iron ions in solution. Next to edibility, an important prerequisite for these particles is that they should be insoluble in the food product, but they should also dissolve once consumed in order to allow the iron to be absorbed by the body. Therefore, metal pyrophosphate salts were used which, while having a low solubility, are still capable of sufficiently fast dissolution in gastric conditions (i.e., pH 1–3) (Rohner et al., 2007 and Wegmüller et al., 2004). Furthermore, as iron-pyrophosphate salts (FePPi) are white, colloidal particles of this material should

be easy to conceal in various food products (van Leeuwen, Velikov, & Kegel, 2012c). In order to further decrease the P-type ATPase reactivity of the contained iron, a second dietary mineral such as calcium or magnesium was incorporated. With this, it was intended to dilute the (surface) concentration of iron in the particles and further reduce its reactivity. An added benefit of these mixed systems is that combining iron with other dietary minerals would make the resulting particles a multi-purpose, widely applicable delivery system for micronutrients (Hilty et al., 2010 and Mehansho et al., 2003). Finally, the colloidal particles were coated with zein, a water insoluble prolamin-class protein from corn. A layer of this hydrophobic protein could help to protect the iron. The protein can then be digested in the gastric tract, releasing its contents which can be dissolved and absorbed.