Physicochemical and Functional Properties of Insoluble Dietary Fiber Isolated from Bambara Groundnut (Vigna subterranea [L.] Verdc.)

Bambara groundnut (BGN) is a widely cultivated legume with a rich nutritional profile, yet despite its many benefits it still remains underutilized. To highlight its potential value, 4 BGN varieties—brown, red, black eye, and brown eye were subjected to sequential enzymatic treatments followed by centrifugation to obtain the insoluble dietary fiber (IDF) fraction. The IDFs were vacuum‐dried and evaluated for color, hydration properties, fat absorption, polyphenolic compounds, neutral sugars, and uronic acids. An optimized white bread formulation was also determined using brown BGN‐IDF in an optimal (IV) mixture design. Three mixture components constrained at lower and upper limits (water: 57% to 60%, yeast: 2.3% to 5.3%, and BGN‐IDF: 7% to 10%) were evaluated for their effects on responses of specific loaf volume, gumminess, chewiness, and resilience of the loaves. All BGN‐IDFs differed significantly (P ≤ 0.05) across all color parameters. Polyphenols were significantly (P ≤ 0.05) highest in red and brown BGN‐IDFs. Arabinose/galactose (31.04% to 37.12%), xylose (16.53% to 27.30%), and mannose (14.48% to 22.24%) were the major sugars identified. Swelling capacity was significantly (P ≤ 0.05) highest for brown eye BGN‐IDF (7.72 ± 0.49 mL/g). Water retention capacity ranged from 1.63 to 2.01 g water/g dry weight. Fat absorption for red BGN‐IDF differed significantly (P ≤ 0.05). Furthermore, the best optimal white bread formulation enriched with brown BGN‐IDF was established with numerical optimization at 59.5% water, 4.3% yeast, and 8.5% BGN‐IDF. Overall positive physicochemical and functional properties were observed for BGN‐IDFs, and it was shown that an optimal white bread enriched with BGN‐IDF could be produced.