Physicochemical properties of starches with variable amylose contents extracted from bambara groundnut genotypes

The physicochemical properties of starches extracted from five bambara genotypes were investigated. Bambara starch granules were predominantly oval shaped with a smooth surface and an average size of 26±0.2μm. The amylose contents (20-35%) varied significantly among genotypes. X-ray diffraction revealed the C-type pattern for all starches with relative crystallinity range: 29-35%. FTIR spectra of bambara starches showed variable peak intensities at 2931, 1655 and 860cm(-1), which corresponds to CH stretching, H2O bending vibrations and CO stretching, respectively. Bambara genotype with the highest amylose content showed the lowest intensity at wavenumber 2931cm(-1). With the exception of oil absorption which was similar, swelling power, water absorption and paste clarity of starches were significantly different among genotypes. Genotype with high amylose content showed restricted swelling, low paste clarity and great ability to absorb water. All bambara starches displayed a shear thinning behaviour (n<1).