Rheological properties of fermented finger millet (Eleucine coracana) thin porridge

Effects of flour solids concentration, cooking time, and temperature on yield stress and apparent viscosity of fermented finger millet pastes were investigated. Static yield stress of pastes increased linearly with cooking time, was independent of flour solids concentration below 4.5%, and increased almost exponentially beyond this concentration. The static yield stress increased with increase in temperature in pastes boiled for 10 min, but decreased in pastes boiled for 1 h. The viscosity curves exhibited shear-thinning behavior and were adequately predicted using Cross equation. Apparent (Bingham) yield stress, derived from Cross parameters, was compared with the static yield stress for various boiling times. Cross parameters displayed bi-phasic temperature dependence in samples boiled for 60 min, with the critical temperature at around 40 °C. Results are explained in terms of starch granule swelling, amylose solubilization, and interactions between the dispersed and dispersing paste phases.