title: Phase stability-induced complex rheological behaviour of galactomannan and maltodextrin mixtures.
abstract: 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.
authors: Institute of Food, Nutrition and Human Health, Massey University, Private Bag 11 222, Palmerston North, New Zealand. K.T.Goh@massey.ac.nz
authors: Kelvin Kim
authors: KK
authors: Tha Goh
authors: May Sui
authors: MS
authors: Mei Wee
authors: Yacine
authors: Y
authors: Hemar
mesh_terms: D005685:Galactans / Q000737:chemistry*; D005690:Galactose / Q000031:analogs & derivatives; D008351:Mannans / Q000737:chemistry*; D008970:Molecular Weight; D053149:Plant Gums / Q000737:chemistry*; D011134:Polysaccharides / Q000737:chemistry*; D012212:Rheology; D033081:Shear Strength; D014783:Viscosity
chemical_list: D005685:Galactans; D008351:Mannans; D053149:Plant Gums; D011134:Polysaccharides; C012990:galactomannan; C008315:maltodextrin; C007894:guar gum; D005690:Galactose