Changes in Physical, Rheological, and Morphological Properties of Various Agglomerated Gum Powders Mixed with an Excipient

In this study, we investigated the physical, rheological and morphological properties of agglomerated xanthan gum (XG), carboxymethyl cellulose (CMC), guar gum (GG) and locust bean gum (LBG) powders used as food thickeners for patients with dysphagia. Compared to their non-agglomerated counterparts, gum powders agglomerated with maltodextrin (MD) as an excipient by using a fluidised-bed granulator exhibited larger, more porous and irregularly shaped structures, resulting in improvements in powder flowability and cohesiveness. In particular, agglomerated CMC had a significantly larger particle size and improved porosity compared to the other gum agglomerates. Although the rheological properties of the agglomerates strongly depended on the gum type, all of them exhibited shear-thinning behaviour, along with an increase in consistency index, apparent viscosity and viscoelastic modulus values at higher concentrations. In addition, agglomerated CMC, GG and LBG exhibited time-independent flow behaviour at a concentration of 1 or 2% in distilled water but anti-thixotropic flow behaviour at 3%. In contrast, agglomerated XG displayed time-independent flow behaviour at 1% and mixed time-dependent flow behaviour at 2 or 3%. These findings suggest that the gum type notably influences the physical, rheological and morphological characteristics of agglomerated gum powders.