Effect of Okra Mucilage Incorporation on the Physico-Chemical and Baking Properties of Wheat–Bambara Groundnut Composite Flour and Bread Quality

The over-dependence of the Nigerian baking industry on imported wheat, together with the limited nutritional density of refined-wheat bread, has intensified interest in composite flour technologies that combine wheat with indigenous, protein-rich legumes. This study evaluated the effect of partial replacement of wheat flour with Bambara groundnut (Vigna subterranea) flour, together with graded levels of okra (Abelmoschus esculentus) mucilage, on the functional properties of composite flours and on the physical, proximate and sensory qualities of the resulting bread. Composite flours were formulated at wheat:Bambara groundnut ratios of 100:0, 70:30 and 50:50, each incorporated with okra mucilage at 0, 5, 10 and 15%, giving twelve formulations arranged in a 3 × 4 factorial design. Bambara groundnut flour and okra mucilage were produced separately and blended with wheat flour prior to bread making; all data were analysed by one-way ANOVA (P ≤ 0.05). Bambara groundnut and okra mucilage inclusion significantly (P < 0.05) improved the functional indices of the composite flour: swelling capacity rose from 9.52 to 11.09%, water absorption capacity from 164.80 to 186.73%, and oil absorption capacity from 108.0 to 158.0%, while bulk density fell from 0.62 to 0.40 g/mL. Loaf weight increased with Bambara groundnut level (111.11–125.90 g), whereas loaf volume and specific volume were generally reduced by gluten dilution, although the 40:50:10 (wheat:Bambara groundnut:okra mucilage) blend produced the highest loaf volume (618.53 cm³). Proximate analysis showed increases in protein (9.04–11.20%), ash (1.57–2.18%) and crude fibre (2.92–4.21%) content, accompanied by a corresponding fall in carbohydrate content (61.19–51.59%). Sensory evaluation, however, showed that acceptability declined once okra mucilage exceeded 5%, owing to a beany flavour and darker colour; the 50:50:0 and 95:0:5 samples were the most preferred among the composites, while the 100% wheat control remained the reference standard. Overall, moderate substitution (up to 50% Bambara groundnut flour with ≤5% okra mucilage) offers a technologically feasible and nutritionally superior alternative to conventional wheat bread, supporting the utilisation of underexploited indigenous crops to reduce wheat importation and mitigate protein–energy malnutrition in Nigeria.