Flow Behaviour and gelatinization kinetics of Brachystegia eurycoma flour and starch dispersions

Abstract

Brachystegia eurycoma flour (5%) and starch (2.6%) dispersions heated for 2,5,10,15,30 and 44 min at 75,80,85 and 90^oC were characterized by pseudoplastic behaviour (0.203<n≤0.329) and (0.249<n<0.429)  respectively with shear thinning effect, and increasing shear stress with shear rate. The consistency coefficient, k, increased with increasing heating time, while the flow behaviour index, n, decreased with increasing heating time. Maximum viscosities attained due to heat-induced gelatinization showed a power relationship with heating temperature. The viscometric measurements showed that starch gelatinization followed a first order kinetic model with the rate constants showing an Arrhenius temperature dependence with an activation energy of 143.43 and 120.91 KJ/mol for Brachystegia eurycoma starch and Brachystegia eurycoma flour.