galactomannan and maltodextrin

Galactomannans (GM), such as guar gum (GG) and locust bean gum (LBG), are extensively used as a thickening agent in the food industry. In this work, the physical, rheological, and structural properties of GG and LBG agglomerated via a fluidized bed agglomerator with different concentrations of maltodextrin (MD) binder were investigated. Agglomerated GM at 40 % MD showed lower Carr index and Hausner ratio, indicating better flowability and lower cohesiveness. The GG showed larger particle sizes than LBG, which was confirmed via SEM images and size distribution profiles. The GM with MD exhibited improved rheological properties. The GG showed lower tan δ values than LBG, indicating the enhancement of their elastic properties. Results exhibit that the physical, rheological, and structural properties of GM can be greatly affected by their agglomerate growths during fluidized bed agglomeration of particles with varying concentrations of MD binder as well as the type of gum.

Topics: Elasticity; Galactans; Galactose; Mannans; Materials Testing; Particle Size; Plant Gums; Polysaccharides; Porosity; Powders; Rheology; Viscosity

The aim of this investigation was to characterize and explain the rheological behaviour observed for mixed solutions of maltodextrin and galactomannans. When 1% w/w guar gum was mixed with 3% w/w low DE maltodextrin (DE 1 or DE 2), the viscosity at low shear rates (~0.1 to 10 s(-1)) decreased by approximately a decade, and exhibited Newtonian behaviour. At intermediate shear rates (~10 to 50 s(-1)), shear thickening was observed, followed by shear thinning at higher rates. The magnitude of these effects increased with increasing concentration and increasing molecular weight (i.e. decreasing DE) of maltodextrin. The underlying mechanism was investigated by studying the stability, rheology and microstructure of the mixtures. The reduction in viscosity at low shear rates is attributed to partial segregation of the more viscous component, guar gum, into a dispersed phase; shear thickening can then be explained by phase inversion under shear, giving a dispersed phase rich in maltodextrin surrounded by a continuous matrix consisting predominantly of guar gum.

Topics: Galactans; Galactose; Mannans; Molecular Weight; Plant Gums; Polysaccharides; Rheology; Shear Strength; Viscosity