Effect of edible plant materials on provitamin A stability and bioaccessibility from extruded whole pearl millet (P. typhoides) composite blends

Blends of cereals and nutrient dense plant materials are increasingly being explored as a strategy for food-to-food fortification in areas of Sub-Saharan Africa, where processing is often applied to enhance product attributes, shelf life and safety. However, little is known regarding the potential impact of these strategies on micronutrient retention and bioaccessibility. In this study whole grain pearl millet (WGM) was blended with carrot powder (source of provitamin A) and Adansonia digitata (Baobab) and Moringa oleifera (Moringa) leaf powders (source of iron) to provide formulations with 25% of the recommended daily allowance (RDA) for Vitamin A. These blends were extruded to produce instant cereal porridges appropriate for consumer markets. Recovery of provitamin A carotenoid ranged from 60.0 to 90.3% after extrusion with higher recoveries in formulations including Moringa and Baobab. Extrusion had a significant negative (p < 0.05) impact on beta-carotene bioaccessibility compared to corresponding dry blends (52% versus 47%; P < 0.05). However, the presence of Baobab in the formulation did enhance provitamin A carotenoid bioaccessibility. These results suggest that extruded blends of native plant materials with whole grain millet has potential to deliver products with stable and bioaccessible provitamin A.