Orange-Fleshed Sweet Potatoes, Grain Amaranth, Biofortified Beans, and Maize Composite Flour Formulation Optimization...

Blending different ingredients can enhance the nutritional value of foods to address the needs of vulnerable populations. This study aimed to develop optimal formulations for raw and extruded flours from orange-fleshed sweet potatoes (OFSP), grain amaranth, biofortified beans, and maize. Blends were extruded using a twin-screw extruder at a barrel temperature of 60°C, 120°C, and 150°C, a screw speed of 350 rpm, and 5% feed moisture. The formulations were optimized using a response surface methodology, with the aim of identifying optimal formulations for raw (RF) and extruded (EF) flours, without (1) or with (2) maize. Formulation optimization was based on the following ranges: OFSP (20%-68%), maize (0%-30%), biofortified beans (20%-40%), and grain amaranth (10%-30%). The response variables were protein, beta-carotene, iron, zinc, and viscosity. Quadratic and cubic models accurately predicted the variables (p < 0.05) with R ² values between 0.93 and 1.00. The first (RF1) and second (RF2) optimal formulations for raw composite flours were OFSP (37.8%), biofortified beans (32.2%), and grain amaranth (30.0%), and OFSP (20.0%), maize (30.0%), biofortified beans (40.0%), and grain amaranth (10.0%), respectively. For extruded composite flours, the optimal formulations (EF1) and (EF2) were OFSP (46.6%), biofortified beans (36.9%), and grain amaranth (16.5%), and OFSP (49.0%), maize (5.9%), biofortified beans (35.1%), and grain amaranth (10.0%), respectively. Formulation and treatment had significant effects on flour composition, pasting properties, and phytochemical content. Extrusion lowered viscosity, while formulations without maize had higher phytochemical content.