Production of weaning food from composites of pearl millet and cowpea

Abstract

Weaning food from pearl millet and cowpea composites was produced using extrusion and press-drying. Sorghum malt was added to the composites to produce drinkable weaning foods. Millet was decorticated and then extruded at several moisture levels. Decortication of millet caused increased starch content and in vitro protein digestibility and decreased protein, lysine, threonine and histidine contents and C-PER. Extrusion at 15% moisture of decorticated (76% yield) millet produced the highest radial expansion, water solubility index and cold viscosity. Extrusion increased the water absorption (WAI) and solubility (WSI) indices, enzyme susceptible starch (ESS) and in vitro protein digestibility of millet. Highly expanded millet extrudate has potential for production of baby foods, snacks or breakfast cereals. Rapid Visco Analyzer (RVA) was used to test the sorghum malt quality and liquefying power on precooked flour. Maximum diastatic activity occurred in sorghum germinated for 3-4 days. In vitro protein digestibility, lysine content and C-PER increased during germination. Sorghum malt was able to liquefy precooked rice or millet pastes within 5 min at 30°C. The RVA adequately measured diastatic activity in a relatively short time using small malt samples. Decorticated millet flour was heated in water and pressed against a hot griddle (press-drying) to produce dry flakes. WAI, WSI and ESS of decorticated millet flour increased after press-drying. This flour had adequate paste property for weaning food preparation. Dehulled cowpea was boiled, ground and press-dried. Press-drying increased the WAI and decreased the WSI of cowpea. Weaning food from extruded or press-dried millet flour (70%) and press-dried cowpea flour (30%) formed smooth pastes after mixing with cold water. Treatment with 5% sorghum malt produced drinkable foods. All experimental and commercial composites had ESS values of >85%. The composites had >17% protein content and >90% of the essential amino acids of the FAO/WHO protein pattern for children less than 1 yr old. Press-drying may have potential in developing countries for production of weaning food with acceptable viscosity and nutritional properties from cereal/grain legume blends.