Optimisation and evaluation of the effect of bambara groundnut addition on the nutritional quality and functional properties of amaranth grain-based composite flour

Abstract

Nutritional quality and functional properties of composite flour consisting amaranth grain, bambara groundnut, carrot and rice bran flours were evaluated. The dependent variables were optimized using optimal mixture model of response surface methodology. Amaranth grain flour (70 - 80.75%), bambara groundnut flour (15-25%), carrot flour (2-5%) and rice bran (2-10%) were the independent variables. From the results, very high protein content (about 40%) was obtained when the bambara content inclusion was 25%. Bambara groundnut flour inclusion up to 15% also resulted in high protein contents (≤ 37%). Supplementation of the composite flour with high carrot flour content (up to 10%) also enhanced the protein content when the bambara groundnut content was low. High carrot flour inclusion had the highest positive effect on the crude fibre content (3.7-3.9%) followed by rice bran and bambara groundnut flours in that order. Bambara groundnut had highest positive effect on the ash content; followed by carrot and rice flours. While amaranth grain, carrot and rice bran significantly (p ≤ 0.05) affect the proximate and functional compositions, bambara groundnut had the highest and best effect on the proximate, functional, mineral properties as well as the amino acid profile of the composite flour.