Okenwa Uchenna Igwe1* and Louis M. Nwokocha2
1Department of Chemistry, Michael Okpara University of Agriculture, Umudike, P.M.B. 7267 Umuahia, Abia State, Nigeria.
2Department of Chemistry, University of Ibadan, Ibadan, Nigeria.
Gum was isolated from the seeds of Brachystegia eurycoma Harms with excess cold isopropanol. The gum constituted 38.1% of the seed endosperm. Proximate composition of the gum showed the presence of protein (2.88%), crude fat (0.62%), ash (1.26%), fibre (0.89%) and moisture (10.35%) but all in very low amounts suggesting high purity of the extracted gum. Cassava and maize starches were used in combination with the isolated gum to investigate certain physicochemical properties. Pasting behaviour of starch/B. eurycoma gum system was probed from its viscosity profiles by means of the Rapid Viscoanalyser. Peak viscosity of the starch/gum system was reduced which was attributed to tighter granular architectural structure. The gum also reduced paste clarity in both cassava and maize starches but cassava starch exhibited more clarity than maize starch. The gum also exhibited better freeze-thaw stability in maize than in cassava starch measured by the amount of water lost during a freeze-thaw cycle called syneresis. These investigations somewhat clarify the role and potential usefulness of B. eurycoma gum in modifying texture and functionalities of starch-based food products especially those of cassava and maize starches.
Keywords: Brachystegia eurycoma, Cassava starch, Maize starch, Rapid viscoanalyzer, pasting properties, Gum