Viscosity and electrical conductivity of concentrated solutions of solublecoffee

Viscosity of concentrated aqueous solutions (omega = 0.5-0.8) of soluble co ffee was measured in the temperature range 25-95 degreesC. After some time of the shear application in the viscometer and passing a temperature of 95 degreesC, the rheological behaviour was found to be Newtonian, The viscosit y was correlated by a five parameter function of coffee mass fraction and t emperature. Specific electrical conductivity of coffee solutions in tap wat er (omega = 0 0.8) was measured in the temperature range 25-72 degreesC. A seven parameter model based on the assumption that the solution is composed of a partially dissociated species and water describes very well the measu red data. A modified Casteel Amis model equation has been identified for co mparison. The conductivity dependence on mass fraction exhibits maxima, whi ch are shifted towards higher concentrations the higher is the temperature. Viscosity, refractivity index, density and thermal conductivity of aqueous coffee solutions (omega = 0 0.5) are reviewed. (C) 2001 Elsevier Science L td. All rights reserved.