Characterization of the root and flour of South African Manihot esculenta Crantz landraces and their potential end-use properties

Abstract

The root and flour of South African Manihot esculenta Crantz landraces (red and white) were characterized for their morphological, physicochemical, metabolic, structural and elemental properties. The results of the colourimetric analysis of the root parenchyma revealed that the L* a* b*, whiteness and brownness index of the white landrace were significantly different (p .05). Cyanide content of the root samples (red – 3.62 mg/kg; white – 3.51 mg/kg) were not significantly different, but the flour samples (red – 2.92 mg/kg; white – 1.83 mg/kg) were significantly different. Granular morphology of flour samples showed spherical and truncated starch granules, clustered and dispersed in no regular pattern. The X-ray diffractometry pattern and main peaks (2θ = 43⁰, 23⁰, 17⁰ and 15⁰) of the flours showed the A-type pattern for both flour samples. Results of all phenolic acids (benzoic and cinnamic acids groups) identified in root samples were not significantly higher in the white landrace. However, a reverse trend was observed with identified fatty acid methyl esters in the landraces. The elemental composition of flour samples showed the presence of essential macro and trace elements in flours. The A-type starch crystallinity of flour exhibited in the red and white landraces positions the flours as a suitable wheat replacement in food applications.

Keywords

• manihot esculenta
• cyanide
• elemental composition
• starch crystallinity
• metabolic profile
• scanning electron microscopy