Effect of African Yam Bean and Carrot Flour Blends Supplementation on the Physicochemical and Microbial Quality of Malted Pearl Millet Flour

Abstract

This study evaluated the quality of composite flours produced from malted pearl millet, African yam bean and carrot flour. The ingredient optimization was carried out and the sixteen runs were generated using the design of optimal mixture and evaluated for functional properties. A significant difference was observed in the functional properties of respective composite flours (malted pearl millet: African yam bean: carrot flour) and samples R4 (72.43:15.28:12.29), R8 (72.83:8.96:18.2), R11 (90:5:5), and R14 (65:30:5) were selected based on the higher bulk density, oil, water, and foaming capacities. In addition, dough rheological properties showed the peak (131-171 RVU), trough (120-155 RVU), and final viscosity (223-265.67 RVU) were all significantly (P<0.05) reduced by the incorporation of African yam bean flour. Increased levels of African yam bean flour resulted in a significant (P<0.05) increase in protein (6.05-15.81%) and low fat (2.81-4.17%). The vitamin A (12.11-34.99 mg/100g) and C (7.68-13.23 mg/100g) concentrations of the composite flours increased significantly (P<0.05) with the carrot flour supplementation. The selected antinutrient contents ranged from 114.84-159.74 (phytate), 18.00-23.65 (tannin), and 0.017-0.182 mg/100g (saponin). The overall heterotrophic bacterial count (1-2.0×104 CFU/100g) and yeast count (3-9×104 CFU/100g) of the composite flours were low. The composite flours did not contain fungi or coliforms, however, Bacillus sp., Saccharomyces sp., and Staph albus were found to be the most prevalent bacteria.