Effect of ultrasound treatment on steady and dynamic shear properties of glucomannan based salep dispersions: Optimization of amplitude level, sonication time and temperature using response surface methodology

Abstract

The present study investigated effect of different amplitude levels (40, 70 and 100%), sonication temperatures (40, 50 and 60 degrees C) and exposure times (3, 7 and 11 min) on steady shear properties: apparent viscosity (eta) shear stress (sigma), consistency coefficient (K), flow behavior index (n) and dynamic shear properties; storage modulus (G'), loss modulus (G ''), complex viscosity (eta*), complex modulus (G*) and loss tangent (tan delta) values of glucomannan based salep solution (SS) and salep drink (SD) samples. In addition, the steady and dynamic shear properties were optimized using ridge analysis in terms of amplitude level, sonication temperature and exposure times levels. Increasing amplitude level and sonication time decreased considerably the eta, sigma, K, G', G '' and eta* values of salep dispersions (SS and SD samples). However, sonication temperature did not have a remarkable effect on these properties. (C) 2011 Elsevier B.V. All rights reserved.