Correlation of the perceived texture of random coil polysaccharide solutions with objective parameters

Abstract

A wide range of concentrated random coil polysaccharide solutions have been assessed for textural attributes by a trained sensory panel. The only textural terms invoked to describe these model systems were ‘thickness’ and ‘stickiness’, which were shown to be highly correlated, and essentially identical numerically, using a ratio scaling technique. Viscosity (η) measurements over a wide range of shear rates (γ) for all these samples gave flow curves (log η versus log γ) of the same form. Differences in flow behaviour between samples could then be characterised completely by two parameters, the maximum viscosity at low shear rates ( η 0), and the shear rate ( γ ̇ 0·1 ) at which η = solη 0 10 . A simple linear relationship was demonstrated between these two parameters and perceived thickness (T) or stickiness (S), irrespective of polysaccharide type. For Newtonian liquids, log T (or log S) varied linearly with log η. Hence the effective ‘in-mouth’ thickness of random coil polysaccharide solutions, in normal viscosity units, may be predicted directly from η 0 and γ ̇ 0·1 by the simple relationship: log η N = 1·13 log η 0 + 0·45 log γ ̇ 0·1 − 1·72 where η N is the viscosity of a Newtonian solution which would be perceived as identical in thickness (and stickiness) to the polysaccharide solution.