Composition, pasting and thermal properties of flour and starch derived from amadumbe with different corm sizes.

Amadumbe, commonly known as taro is a traditional southern African tuber crop. In this study, the effect of corm size: large, medium and small on composition and functional properties of amadumbe flours and starch isolates was determined. With the exception of iron and zinc, the basic chemical composition of amadumbe flours was not affected by differences in corms size. Amadumbe flours contained substantial amount of carbohydrates and limited contents of protein and fat. However, flours derived from large and small corms had iron contents (approx. 3 mg/100 g), which was 3 times that of medium corms. Large corms flour had the highest Zn content (2.6 mg/100 g). Amadumbe corms showed polygonal and small sized (1-5 µm) starch granules containing varying levels of amylose (13-16%). Starch isolates showed reflective peaks at 15° (2) and doublet at 17° and 18° typical of A-type starches. Peak viscosity, gelatinisation temperatures and final peak viscosity significantly varied among amadumbe corm types possibly due to variation in amylose contents. Flour mineral content, starch amylose and functionality differ with corm types.