Abstract

This study investigated the flow behaviour of some food gruels obtained from pre-treated banana, sorghum or sesame flours. The Herschel-Bulkley and the power law models were used to evaluate the consistency and flow indices while an Arrhenius-type equation was used to analyse the effect of temperature on viscosity. The Ostwald de Waele model gave a good fit with experimental data, with p-values less than 0.01 and R² values greater than 0.96 for most of the experiments. The results revealed a pseudoplastic, dilatant and time independent character for the sorghum gruels while the sesame and banana gruels revealed a pseudoplastic and time-dependent character. The effect of temperature on viscosity led to an activation energy and second Arrhenius parameter varying from 964 to 21,070 J.mol^-1 and from 81 to 34,484 Pa.s respectively. The concentration dependence of the consistency index was modelled using an exponential equation and showed a decrease with temperature.

Key words: Sorghum gruel, sesame gruel, banana gruel, power law, Arrhenius law, time dependency.