RHEOLOGY OF MULBERRY PEKMEZ

The rheological behavior of mulberry pekmez (concentrated mulberry juice, °Brix = 72.0) with different solid contents (62.8, 55.8 and 46.0) was studied over the temperature range of 10, 20, 30, 40, 50 and 60C using a Controlled Stress Rheometer. Mulberry pekmez was found to exhibit Newtonian behavior. The effect of temperature can be described by means of Arrhenius equation. The activation energies for flow of samples vary from 53.11 to 12.73 kJ/mol depending on soluble solid contents. The effect of soluble solids on viscosity can be described by an exponential equation. The best model to describe the combined effects of temperature and soluble solids content on viscosity is η= 3.40 X 10^-10 exp (0.12C + 3723/T).