Dissolution kinetics of guar gum powders—III. Effect of particle size

The functional properties of guar gum, which are of considerable importance in biological, industrial and biotechnology processes, are crucially dependent on the rate and extent of dissolution in an aqueous solvent. This work investigates the effect of particle size on the hydration rate of guar gum powders over a wide range of particle sizes. A logarithmic model described in a previous paper for studying the hydration kinetics of commercial guar flours was not applicable for some of these samples, because they were of a very much larger particle size, outside the usual commercial range. For this reason, a new approach was developed to describe the hydration process of these guar gum granules. It was found to be suitable for describing the hydration process of guar powders with a wide range of particle size, by introducing size-dependent hydration indices. This approach involves the construction of a master plot, but the ‘shift factors’ are related to particle size and the hydration time. This model consequently allows some new physical insights to be developed.