Colloidal iron(III) pyrophosphate particles

• Colloidal iron(III) pyrophosphate particles were prepared using a wet chemistry method.
• Submicron in size, white and amorphous iron-containing particles were obtained.
• Particle density and refractive index were determined.

Ferric pyrophosphate is a widely used material in the area of mineral fortification but its synthesis and properties in colloidal form are largely unknown. In this article, we report on the synthesis and characterisation of colloidal iron(III) pyrophosphate particles with potential for application as a food additive in iron-fortified products. We present a convenient and food grade synthetic method yielding stable colloids of nanometre size with a distinctive white colour, a unique characteristic for iron-containing colloids. Physical properties of the colloids were investigated using different techniques, to assess particle crystallinity, surface charge, mass density, refractive index, internal structure, elemental composition and magnetic properties. The findings of this research are especially relevant for food and beverage science and technology and will help develop a more effective use of these fortifiers in colloidal form.