Rheological characteristics of South African commercial sauces

Abstract

In this work, the rheological characteristics of three commercial culinary sauces obtained from a shop in South Africa were studied using both oscillatory and rotating rheometry. The materials were found to be non-Newtonian and shear thinning in the temperature range of 10 °C and 60 °C and a shear rate of 0.1–800 s−1. Their flow behaviour characteristics were adequately described by both the power law and Herschel–Bulkley rheological models. Their activation energy of flow ranged from 11.94 to 18.34 kJ mol−1. The materials were observed to be weak gels with linear viscoelastic of about 1%. Increasing frequency did not significantly affect the viscoelastic properties of all the three substances. The materials were found to suffer permanent structural deformation (in terms of viscosity) when heated and subsequently cooled between 10 °C and 70 °C.