Isolation, chemical modification and physicochemical characterisation of Bambarra groundnut (Voandzeia subterranean) starch and flour

The proximate and physico chemical characterisation of Bambarra groundnut (Voandzeia subterreanea) flour and starch was studied. Oxidation and acetylation of the native starch reduced the percentage ash, crude protein, crude fibre, and crude fat. The swelling capacity increased with increase in temperature for both starch and flour; the acetylated starch, however, showed the highest swelling power. There is increased swelling and solubility in the alkaline region. Oxidized starch had the highest oil and water absorption capacity (3.04 and 2.40 g/g, respectively). The least gelation concentration for the starches ranged from 6 to 10% (w/v), while the alkaline water retention increased when the starches were blended with wheat flour, with the blends of wheat flour and acetylated starch giving the best result. Brabender viscographic studies showed lowering of pasting temperature after oxidation and acetylation, with oxidised starch showing the lowest pasting temperature. Both oxidation and acetylation lowered the peak viscosity (PV), hot paste viscosity (Hv) and cold paste viscosity (Cv). Chemical modification enhanced the stability of the starches with oxidised starch having the highest stability value, followed by acetylated starch.