Development and nutritional evaluation of an extruded grain amaranth-instant porridge as a supplementary food for children under five with moderate acute malnutrition

Moderate acute malnutrition (MAM) among children under five remains a challenge in Tanzania, where the fortified blended foods used to manage it are almost entirely imported, expensive and inaccessible. This study developed and evaluated a grain amaranth-based extruded instant porridge as a locally sourced alternative. Five formulations were generated from grain amaranth, pro-vitamin A maize, soybean and sesame by two-stage linear programming using regional food composition data, with crude protein maximized subject to a technological fat ceiling of 11.0 g/100 g. Formulation 1, the least-cost solution, and Formulation 5, the most nutrient-dense within fat ceiling that is more economical than the non-compliant Formulation 3, were advanced to twin-screw extrusion. Proximate composition (AOAC 2005), mineral content (microwave plasma atomic emission spectrometry) and anti-nutritional factors (colorimetric methods) were determined; functional and sensory properties were evaluated; data were analyzed by ANOVA. Protein ranged from 18.14 g/100 g in Formulation 1 to 20.53 g/100 g in Formulation 5 reaching 98.0% of the WFP/UNICEF Super Cereal Plus (CSB++) minimum of 400 kcal/100 g. Formulation 5 showed the highest fat (11.95 g/100 g) and zinc (8.98 mg/100 g), all within CSB++ ranges, with only potassium below specification (37.1%). Extrusion significantly increased water absorption capacity ( p < 0.001), shifted the flour from the fair to good flowing category, and reduced tannins, oxalates and phytate by 50.2, 64.9 and 77.6% relative to raw grain amaranth. Sensory scores showed good overall acceptability (6.2–6.9), with significant differences for aroma ( p < 0.001) and flavor ( p = 0.002); SC(F5)-777 ranked highest among extruded samples. Food-to-food fortification using grain amaranth at 40–45% produced energy- and nutrient-dense instant porridge with improved mineral content, functional properties, and sensory characteristics, demonstrating strong potential for use as locally available supplementary food for managing MAM in children under five.