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

Published Date
20 November 2015, Vol.133:171–178, doi:10.1016/j.carbpol.2015.06.100

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

• Samson A. Oyeyinka ^a
• Suren Singh ^a
• Patrick O. Adebola ^b
• Abe S. Gerrano ^b
• Eric O. Amonsou ^a,,

• aDepartment of Biotechnology and Food Technology, Durban University of Technology, Durban, South Africa
• bAgricultural Research Council, Roodeplaat -Vegetable and Ornamental Plant Institute, Pretoria, South Africa

Received 25 March 2015. Revised 20 June 2015. Accepted 26 June 2015. Available online 10 July 2015.

Highlights

• •
  Bambara starch were predominantly oval shaped with average size of 26 ± 0.2 μm.
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  Amylose contents of bambara starches varied significantly (20–35%) among genotypes.
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  Bambara genotypes contained the C-type starches with relative crystallinity range: 29–35%.
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  Genotype with the highest amylose content showed weak FTIR peaks at 2931 and 1655 cm⁻¹.
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  Genotype with high amylose showed restricted swelling, low paste clarity and high viscosity.

Abstract

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 ± 0.2 μm. 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 860 cm⁻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 2931 cm⁻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).

Keywords

• Bambara
• Genotypes
• Physicochemical properties
• Rheology
• Starch

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• ⁎ 
  Corresponding author. Tel.: +27 313735328.

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