Flow Behaviour of Black Chokeberry (Aronia melanocarpa) Juice

The viscosity of the concentrated black chokeberry juice has been studied at the soluble solids content of 50 - 67.8 degrees Bx and the temperature range of 10 - 60 degrees C. On the base of obtained results it was shown that concentrated black chokeberry juice exhibited Newtonian flow behaviour. The values of the viscosity strongly depended on the concentration and temperature and were in the range from 5.8 to 436.6 mPa s. To study the influence of soluble solids content on the viscosity, power-law and exponential functions were used. The effect of the temperature on the viscosity was described by the Arrhenius equation and the values of flow activation energy were in the range from 22.84 to 40.28 kJ/mol. Additionally, equations based on the Arrhenius and power-law or exponential functions describing combined effect of the soluble solids content and temperature on the viscosity were obtained. Because the values of flow activation energy strongly depended on the concentration, four parameters model for the concentrated black chokeberry juice was proposed.