Rheological properties of banana puree at high temperatures

Abstract

The rheological behavior of banana puree was determined using a dynamic stress rheometer with a pressure couette fixture, which allowed experiments to be conducted at high temperature. The pressure couette was pressurized with compressed air to 206.8 kPa (gage pressure) and experiments were carried out at temperatures ranging from 30 to 120°C. The shear stress values ranged from 10 to 170 Pa and the shear rate values from 10-5 to 10 3s-1. The model that best fitted the experimental data at all temperatures was the Herschel-Bulkley model. There was a usual tendency for the apparent viscosity to decrease with increasing temperature but an increase in apparent viscosity with increasing from 50 to 60°C and from 110 to 120°C was found. This could be due to interaction of polysaccharides present in banana puree. There was a slight difference between the apparent viscosity values for increasing shear stress sweeps and those for the decreasing shear stress sweeps suggesting time dependency of the rheological behavior. Models were proposed to correlate the parameters of the Herschel-Bulkley model and viscosity with temperature.