Food-to-Food Fortification of Ready-to-Eat Cereal-Based Porridges: A Potential Sustainable Food-Based Strategy to Improve Bioavailable Iron and Zinc in Plant-Based Diets

Abstract

Abstract Objectives Iron and zinc deficiencies are prevalent in Africa, including urban populations, often due to monotonous plant-based diets low in bioavailable minerals. Food-to-food fortification (FtFF) is an emerging tool in the fight against mineral deficiencies. However, due to rapid urbanisation in Africa, demand for ready-to-eat (RTE) staple foods is increasing. This study investigated whether FtFF with plant foods rich in minerals (moringa leaves) and their bioavailability enhancers, organic acids (baobab fruit) and β-carotene (mango, papaya) at 2.5–14.9 g/100 g porridge with micronutrient premix (MP) can improve iron and zinc bioaccessibilities in extrusion-cooked wholegrain pearl millet-based porridges. Methods Three extrusion-cooked pearl millet-based porridges were formulated: 1) Pearl millet + carrot + mango + baobab + moringa; 2) Pearl millet + carrot + papaya + baobab; 3) Pearl millet + carrot + papaya + baobab + MP (iron (2.1 mg) zinc (1.65 mg), vitamin A (840 IU)). Raw pearl millet served as the control. Porridge mineral, phytate and total phenolics contents were determined. In vitro equilibrium dialysability assay was performed to predict mineral bioavailability. Results The RTE FtFF-porridges had higher bioaccessible iron than pearl millet (p < 0.05), in terms of percentage and amount, by up to 23-fold. However, the porridges were unnaturally high in iron due to contamination from the extruder cooker parts. FtFF with combinations of carrot, papaya, baobab plus MP or with carrot, mango, baobab plus moringa leaves increased bioaccessible zinc (p < 0.05), in terms of percentage and amount, by up to 4-fold, with the porridge containing MP enhancing iron and zinc bioaccessibility the most. The organic acids and β-carotene contents plus the low pH (3.0–5.2) of the food fortificants likely enhanced the solubility of the contaminating iron and the intrinsic iron and zinc in the porridges. Extrusion cooking reduced the porridges’ phytate contents, by 35–50%, hence, likely contributed to the increased mineral bioaccessibilities. Conclusions Thus, such ready-to-eat food-to-food fortified wholegrain cereal-based porridges may be a sustainable food-based strategy to improve bioavailable iron and zinc in the diet of at-risk urban populations in Africa. Funding Sources USAID, South Africa National Research Foundation/TWAS.