Functional and Pasting Properties of Citric Acid Cross-Linked Tigernut Starch

Abstract

Tigernut (Cyperusesculentus L.) is an underutilised crop though widely cultivated in several countries. The starch was isolated and cross-linked with citric acid. The functional properties of the starch were altered and characterized. Characterization using FTIR yielded a characteristic peak at 1720 cm-1 suggesting the presence of starch citrate esters. Modification of Tigernut starch was also shown to affect its functional properties, such as swelling power, solubility and viscosity. Starch water absorption and emulsion capacity increased from 80.0 % and 15.33 % to 94.0 % and 18.34 %, respectively. Cross-linked starch (CTS) had better swelling power and solubility in all the temperature range 50 – 90°C compared with native starch (NTS). The result shows that cross-linking treatment drastically increased the lipophilic power of tiger nut starch. The formation of starch-citrate bonds accounted for the effects observed. The properties shown by the modified starch synthesized make them good candidates for application in food processing as thickening agents and stabilizers in ice screams yoghurts etc.