Effect of foaming agents on the stability, rheological properties, drying kinetics and flavour retention of tamarind foam-mats

Tamarind foam-mats were prepared using as foaming agents ovalbumin, mesquit e gum and a low molecular weight surface active blend, by themselves or in combination, in accordance to a 2(3) factorial experimental design. The sta bility, theological properties (flow and viscoelasticity) and drying kineti cs of the different foam treatments were evaluated. Sensory evaluation of t he dried powders was performed. Response surface analysis yielded polynomia l models that explain the influence of the foaming agents treatments on the selected foams response variables: drainage mean time, yield stress, appar ent plastic viscosity. critical drying time, instantaneous elastic modulus, and mean retardation time. In general terms, the use of binary combination s of the foaming agents at their high usage level yielded foams that exhibi ted longer drainage mean times: higher yield stress, apparent plastic visco sity, instantaneous elastic modulus and mean retardation times; and a short er onset of the critical drying time, that yielded dried tamarind powders w ith better sensory flavour perception. A close interrelationship existed be tween the drainage mean time and the apparent plastic viscosity. and betwee n the critical drying time and the mean retardation time of the foams. (C) 2001 Elsevier Science Ltd. All rights reserved.