Rheological properties of enzyme-treated mango pulp

Mango pulp was treated with pectinase enzyme at different times (30-150 min) and temperatures (25-60 degrees C) of treatment, and at various concentrations of enzyme (0.005-0.095%). The effect of these enzyme treatment conditions on the rheological parameters (yield stress, flow behaviour index and consistency index) and the apparent viscosity were determined employing a second order central composite rotatable design in combination with response surface methodology. The raw, as well as the enzyme-treated mango pulp behaved as pseudoplastic liquid and possessed yield stress. The Herschel-Bulkley model fits well (r greater than or equal to 0.991, p less than or equal to 0.01) the shear rate and shear stress data. An increase in time and/or concentration of enzyme treatment is associated with art increase in the flow behaviour index. Apparent viscosity markedly decreased with an elevation in the concentration of the enzyme. (C) 1998 Elsevier Science Limited. All rights reserved.