Minimization of cassava paste flow properties using the ‘Farris effect’

Cereals and tuber crops are the raw materials for thin porridges meant for infant feeding in many parts of the world. However, the high viscosity and low energy density of such starchy porridges limit their use as complementary foods. In this study, we have employed the so-called “Farris effect” to minimize the apparent viscosity of cooked cassava pastes. The particle size distributions of cassava flour, ground to varying degrees of fineness, were obtained using a laser diffraction particle size analyzer. Pastes were then prepared at various flour solids concentrations by boiling for 15 min under reflux. Flow properties were then determined at 25±0.02 °C over the shear rate range 0–1200 s−1 using a Haake Rheostress I rheometer. The swelling power, extent of solubilization, volume fraction at maximum packing, paste viscosity, and yield stress all depended on the average flour particle size. By mixing fine and coarse flours of different particle size distributions, the apparent viscosity and yield stress of the resulting pastes were reduced by over 20% at a some critical volume fraction and particle size ratio. This technique could provide an effective means of improving the energy density of cereal and root crop-based thin porridges.