Isolation and physicochemical characterization of fonio (Digitaria exilis stapf) starch

Abstract

Fonio (Digitaria exilis Stapf) starch was isolated from the seeds of two varieties denominated Hothia and Koutli and its physicochemical properties were compared with those of commercial wheat starch. Fonio starch granules seen under a SEM had polygonal shapes and small size (about 8μm). Amylose content of Hothia (22.6%) was significantly lower than that of Koulli and wheat (26.1% and 25.0%, respectively). There was not any significant difference in lipid content of fonio starches (2.8% and 2.9%), whereas significant differences were observed in their water binding capacity (88% and 80%). Protein and ash were also determined. The swelling power and solubility of wheat and fonio starches within the 50°C-90°C temperature range were also studied. Brabender amylograms of 5% fonio starch slurries showed similarly shaped, single-step curves. However, the two fonio varieties reached quite different viscosity values during the heating and cooling cycle.