High frequency dynamic shear rheology of honey

Abstract

Our objective was to measure the high-frequency dynamic shear rheology of honey using ultrasonic spectrometry. The complex shear reflection coefficient of honey was determined over a range of frequencies (5–15 MHz) by measuring the phase and amplitude of ultrasonic shear waves reflected from its surface. The dynamic shear modulus and dynamic viscosity of the honey were determined from the measured reflection coefficient and density. For honey samples diluted with different amounts of water there was a strong correlation between the viscosity measured at high shear-rate (10 MHz) using ultrasound and that measured at low shear rate (0.1 s −1) using a Couette viscometer. Nevertheless, the viscosity was significantly lower at high shear-rates than at low shear rates, which indicated the existence of one or more relaxation mechanisms. Our results show that ultrasonic spectrometry can be used to non-destructively and non-invasively measure the high frequency shear rheology of honey samples, which may be useful for quality control of honey and other viscous products.