Effect of pH, temperature and glucose addition on flow behaviour of fruit purees - I. Banana puree

The influence of pH (3.0 and 5.1) and addition of glucose to attain water activities (a(w)) ranging from 0.89 to 0.97 on the flow behaviour of banana purees was evaluated in the temperature range 10-55 degrees C. All purees were shear-thinning fluids with appreciable yield stress values, the flow curves essentially following the Herschel-Bulkley model. Glucose addition generally decreased the apparent viscosities and increased the temperature dependence of the flow properties. There were no patterns with respect to the effect of pH on flow characteristics. The effect of temperature (10-40 degrees C) and concentration (21.4-50.9 degrees Brix) on the consistency coefficient was represented by a single derived by combining an Arrhenius type relationship for the dependence on temperature and an exponential relationship for the influence of concentration. (C) 1997 Elsevier Science Limited. All rights reserved.