Modelling of rheological properties of honey as influenced by temperature changes

Abstract

This work investigated the influence of temperature variation (5 to 40^oC) on honey viscosity at a low shear rate of 0.01 to 4.2s^-1, along with other honey samples collected randomly from the market. The essence of this study was to reveal the authenticity of what is sold in the open market as honey, by differentiating pure from adulterated ones. Four models, Ostwald de-Waele Power-law, Malcolm Cross, Arrhenius, and Temperature-dependent Power-law models were applied to fit the effect of temperature treatment on the sample’s rheological behaviour. Honey at room temperature exhibited time-independent non-Newtonian rheological characteristics. It shows dilatant rheological character at the outset of flow at shear rates of (0.01-0.1s^-1) and then predominantly shear-thinning (pseudoplastic) behaviour up to the shear rate of 3.910s^-1 after which the viscosity flattens to Newtonian behaviour. The rheological curve-fit results obtained from the Malcolm Cross model correlated well with the rheological data, unlike the Oswald-de Waele Powerlaw model where large discrepancies were observed. The Arrhenius model produced a good agreement with the experimental data. One of the samples randomly picked from Igbogiya town (sample B) exhibited the character of an adulterated sample.