Effect of annealing and heat moisture conditioning on the physicochemical characteristics of Bambarra groundnut (Voandzeia subterranea) starch.

Isolated starch of Bambarra groundnut (Voandzeia subterranean) was subjected to hydrothermal modifications through annealing and heat moisture conditioning. Both annealing and heat moisture conditioning reduced the swelling power and solubility of the starch. Water binding capacity reduced after annealing heat moisture conditioning at 18% moisture level (HMB18) and heat moisture conditioning at 21% moisture level (HMB21). Both heat moisture conditioning at 24% moisture level (HMB24) and heat moisture conditioning at 27% moisture level (HMB27) increased the water binding capacity. Hydrothermal modifications reduced the oil absorption capacity of the raw starch. Annealing and heat moisture conditioning reduced the peak viscosity (Pv), viscosity at 95 degrees C (Hv) and viscosity at 95 degrees C after 30 min holding (Hv30). However, viscosity increased on cooling down to 50 degrees C after annealing. Annealing and heat moisture treatments as revealed by scanning electron micrograph and light micrograph did not alter the shape and size of the raw starch. The results indicate a rearrangement within the starch granule following hydrothermal treatments.