Rheological properties of aseptically Packaged tomato concentrates

Abstract

Rheological properties of tomato concentrates were evaluated by using a Haake rheometer RV20 at different concentration stages: 10, 15, 20, 25 and 30 ^oBrix in order to obtain the flow curves and also the relationship between apparent viscosity and yield stress with concentration. 20 ºBrix concentrate was independently evaluated at different temperatures (30 to 80 ºC) and Arrhenius model was fitted for the calculation of the activation energy for viscous flow. It was concluded that all the concentrates shows yield stress and that the Herschel-Bulkley equation is adequately to describe their flow behaviour. Concentration effects over apparent viscosity and yield stress shows an exponential relationship where the exponent is 1.74 in both cases. Activation energy for viscous flow in the range 30 to 80 ^oC was 1.9 kcal/mol^oK.