Structure and functional properties of starch and flour from bambarra groundnut

Structure and functional properties of starch and flour from Bambarra groundnut (Voandzeia Subterranea) were investigated. The bambarra groundnut flour contained 58.38% of carbohydrate, 15.48 % of protein, 7.90% of fat, 4.19% of ash and 2.54% of fiber content. The starch isolated by the alkaline method had low content of protein (0.61%), fat (0.44%) ash (0.47%) and fiber (0.60%). Amylose content of bambarra groundnut starch was 21.67%. The starch granule shape appeared to be oval and round having an average diameter of 31.11 mm. X-ray diffraction pattern of the starch granules revealed an A-type with 43.69% of crystallinity. Thermal transition temperature of the starch assessed by DSC was 71.69oC at onset (T0) and gelatinisation enthalphy (DH) was 11.73 J/g. Water and oil absorption capacity of bambarra groundnut starch were 1.67 and 1.01 ml/g, respectively. Bambarra groundnut starch showed a two-stage swelling pattern indicating a fairly restricted swelling starch. The pasting properties of the starch showed pasting temperature, breakdown and setback of 77.7oC, 170 BU, 220 BU, respectively. The starch showed similar pasting characteristics at the pH range 4.6 to 7.0. Compared with bambarra groundnut flour, the starch exhibited higher swelling power, breakdown and setback, but lower gelatinisation temperature, pasting temperature, water and oil absorption capacity.