Extraction and Characterisation of Starch from Cocoyam Corms in Imo State

Cocoyam (Colocasia esculenta) is an underutilised but widely grown crop in Imo State, South East Nigeria, with significant potential as a starch source for food and industrial applications. This study extracts and characterises starch from three cocoyam varieties cultivated in Owerri and Orlu zones. Starch extraction was performed using a wet alkaline method, and starch yield and purity were determined gravimetrically and by iodine binding capacity. Physicochemical characterisation included moisture content, ash content, protein content, amylose and amylopectin content, granule morphology by scanning electron microscopy, and X-ray diffraction pattern. Functional properties measured were water absorption capacity, oil absorption capacity, swelling power, solubility index, and pasting properties using a Rapid Visco Analyser. Results showed starch yields between 14.2 and 17.8 percent on a fresh weight basis across varieties. Scanning electron microscopy revealed round to oval granules of 1 to 3 micrometres, consistent with literature values for taro starch. Amylose content ranged from 18 to 22 percent across varieties. Peak viscosity ranged from 380 to 510 RVU, indicating suitability for thickening applications. The study contributes to the growing literature on underexploited tropical starch sources and provides a characterisation baseline for industrial application development. Findings are relevant for food product developers, starch processing companies, and the Imo State Agricultural Development Programme. Keywords: cocoyam, starch, characterisation, pasting properties, Imo State