Molecular and physicochemical characterisation of starches from yam, cocoyam, cassava, sweet potato and ginger produced in the Ivory Coast

Abstract

Abstract Granule sizes, macromolecular features and thermal and pasting properties of starches from seven tropical sources (Florido, Kponan and Esculenta yams, cocoyam, cassava, sweet potato and ginger) were compared with those of several well‐known cereal, legume and tuber starches. The aim of the study was to characterise some non‐conventional starches with a view to possibly marketing them. Amylose content varied from 148 mg g −1 in Esculenta starch to 354 mg g −1 in smooth pea starch. For total starches, weight‐average molar mass ( M̄ w ) ranged between 0.94 × 10 8 and 1.80 × 10 8 g mol −1 for potato and normal maize starches respectively. Gyration radius ( R̄ G ) varied from 157 nm for ginger starch to 209 nm for normal maize starch. Gelatinisation enthalpy (Δ H ) ranged between 9.8 and 20.7 J g −1 for wheat and Florido starches respectively. Gelatinisation peak temperature ( T g ) varied from 58.1 °C for wheat starch to 87.3 °C for ginger starch. Native starch granule mean diameter ranged between 5.1 and 44.5 µm for Esculenta and potato starches respectively. Cassava and potato starches had the highest swelling power and dispersed volume fraction at all treatment temperatures, while ginger starch had the lowest. Cocoyam starch had the highest and ginger starch the lowest solubility at 85 and 95 °C. Cassava starch was the most stable under cold storage conditions. Roots and tubers such as ginger and cassava produced in the Ivory Coast are new sources of starches with very interesting properties. Thus these starches could be isolated on an industrial level in order to market them. Copyright © 2007 Society of Chemical Industry