Kinematic viscosity and water activity of aqueous solutions of glycerol and sodium chloride

Abstract

During osmotic dehydration, a removal of water from foodstuffs is achieved with a decrease in the water activity of the food sample. This dehydration process involves the utilization of highly concentrated solutions with one or several solutes that increase considerably the viscosity of the liquid phase. This property is fundamental in the studies of mass and momentum transfer processes. Glycerol and sodium chloride are studied as systems employed in this type of process due to the advantages for the final dehydrated product. Kinematic viscosities of binary and ternary aqueous solutions of these solutes were measured at various concentrations (from 0 to up 5.0 mol kg−1) and temperatures (from 20 up to 50 °C). Water activities for each indicated solution at 25 °C are also reported. Experimental data for both physical properties were simultaneously correlated with concentration and temperature for binary and ternary solutions with a suitable accuracy. Additionally, relationships between kinematic viscosities and water activities were established.