Onwuakor C.E.^1,, Onwuakor A.G.², Ohaegbu C.G.¹, Umeh M.N.¹, Uzoka J.I.¹, Uchendu C.E.³

Products based on African breadfruit (Treculia africana) are limited by low protein content, weak gel formation and pronounced serum separation. This study evaluated whether Bambara groundnut (Vigna subterranea) protein concentrate (BPC) and okra (Abelmoschus esculentus) mucilage, added separately and together, could improve the fermentation, physical stability, rheology and sensory acceptability of a breadfruit beverage fermented with Streptococcus thermophilus and Lactiplantibacillus plantarum. Six systems were produced: an unenriched control (ABM), BPC at 1 and 2 g/100 g (1BPC, 2BPC), okra mucilage at 0.15 g/100 g (OM), and the two combinations (1BOM, 2BOM). Enrichment accelerated acidification, cutting the time to reach pH 4.50 from 10.60 h to 8.10 h and raising the maximum acidification rate from 0.310 to 0.441 pH units h⁻¹. Mass-balance estimates indicated the beverage protein content rose from 2.08 g/100 g in ABM to approximately 3.47 g/100 g in 2BOM. The combined treatment (2BOM) gave the highest starter counts (8.74 and 8.28 log₁₀ CFU g⁻¹) and lactic acid (1.04 g/100 g), reduced phase separation from 24.6% to 0.8% and syneresis from 52.4% to 8.6%, and raised gel firmness more than fifteen-fold. All beverages were shear-thinning, and 2BOM showed the highest apparent viscosity (3.86 Pa·s at 10 s⁻¹) and consistency coefficient (18.91 Pa·sⁿ). Gel firmness correlated inversely with syneresis (r = −0.929) and apparent viscosity with phase separation (r = −0.888). Sensory scores and an exploratory principal component analysis (PC1 = 72.4% of variance) both favoured the combined systems (overall acceptability 8.3/9). Pairing a legume protein concentrate with a small amount of okra mucilage therefore produces complementary effects, protein driving fermentation and gel formation and mucilage governing water retention, yielding a stable, well-liked plant-based fermented beverage suitable for smallholder and small-scale industrial production.

African breadfruit beverage, lactic acid fermentation, Bambara groundnut protein concentrate, okra mucilage, syneresis