Chemical, Functional and Pasting Properties of Defatted Starches from Cowpea and Soybean and Application in Stiff Porridge Preparation

Abstract

The effects of defatting on the chemical, functional and pasting properties of starches from cowpea and soybean and their application in stiff porridge preparation were studied. Conventional cassava starch served as standard. Defatting of cowpea and soybean resulted in higher yield. Defatted starches also had higher amylose contents with low protein, fat and ash contents than full fat starches. In addition, defatted starches from cowpea and soybean had higher water absorption capacity, swelling power, blue value index and low bulk density, higher peak viscosity, trough, final viscosity, setback values than full fat cowpea and soybean starches while cassava starch had higher peak time and pasting temperature than the legume starches. The full fat starches from soybean and cowpea had high breakdown and low setback values than the defatted samples and control. The extensibility values of defatted starches were significantly (p . 0.05) higher than full fat starches but lower than control. There was no significant (p . 0.05) difference in texture and appearance of stiff porridges prepared from cowpea, soybean and cassava starches. Similarly, there was no significant (p . 0.05) difference in mouldability, stickiness and overall acceptability between defatted starches and control but significantly different (p . 0.05) with the full fat starches. It is therefore concluded that consumption of such stiff porridges could be beneficial to individuals requiring decreased and/or slow starch digestibility such as diabetic patients and long distance athletes since legume starches are known to have low starch digestibility.

Keywords: Legume starch, yield, functional, chemical composition, pasting, stiff porridge.