Rapid determination of emulsion stability by rheology-based thermal loop test

Abstract

This study aimed to determine the stability of oil-in-water emulsions using the thermal loop test as a novel method. Samples with xanthan gum concentrations of 0.1 g, 0.2 g, 0.3 g, 0.4 g or 0.5 g/100 g were subjected to 10 thermal cycles from 5 to 23 °C (low-temperature stability test) and 23–45 °C (high-temperature stability test). In the low-temperature stability test, the relative change of G* for the samples (Δ) was 4.15%, 2.82%, 1.32%, 1.17%, and 4.68%, respectively. In the high-temperature stability test, the Δ values were 7.7%, 0.58%, and 7.22% for samples 3–5, respectively. However, samples 1 and 2 had dramatic changes in G*. This was also confirmed by a visual test, zeta potential measurement, polydispersity index, and particle size distribution. Moreover, a low zeta potential, high polydispersity indexes, and phase separations yielded high Δ values. This study implies that the thermal loop test could be successfully applied to determine the emulsion stability in food emulsions.