Rheology and microrheology of natural and reduced-calorie Israeli honeys as a model for high-viscosity Newtonian liquids

Honey is a food biomaterial that has been used as a natural therapeutic agent against infections and to stimulate wound healing; its flow behavior is interesting as it affects processing and consumption. The temperature- and composition-dependence of honey viscosity was measured in selected Israeli varieties. Classical rheology was compared to thermal-fluctuation particle-tracking microrheology. In particle-tracking, the viscosity is measured on a sub-micron scale, providing contributions of different regions in the sample. Honey viscosity was Newtonian, even in reduced-calorie varieties, and adhered to the Arrhenius equation, viscosity exponentially decreasing with temperature. The Arrhenius activation energy and viscosity were moisture-dependent. Our data are comparable to previously reported honey rheology from different regions in the world. In conclusion, we show that rheology agrees with microrheology, as expected for a Newtonian liquid. Moreover, we have shown that high-viscosity samples can be accurately characterized using particle-tracking microrheology, providing additional information to rheology.