The polysaccharide gel layer surrounding hydrated chia seeds was extracted using water and isolated by ethanol precipitation. The freeze-dried sample consisted of ∼95% non-starch polysaccharides (35% w/w neutral soluble fraction and 65% w/w negatively charged insoluble fraction). The soluble polysaccharide fraction has molar mass, root-mean square radius and intrinsic viscosity of ∼5×10(5)g/mol, 39nm and 719mL/g, respectively. The whole polysaccharide (included soluble and insoluble fractions) when dispersed in water showed presence of irregular shape, fibrous microgel particles with an average size (D4,3) of ∼700μm. Rheological measurements indicated a 'weak' viscoelastic gel and strong shear dependent properties even at low concentration (0.05% w/w). The viscosity of the dispersion was fairly resistant to variations in temperatures (20-80°C), pH (4-12), ionic strengths (0.01-0.5M NaCl) and cation types (MgCl2, CaCl2, NaCl and KCl). The swollen microgel particles dispersed in soluble polysaccharide continuous phase provided complex and potentially useful rheological properties in food systems.
Keywords: Chia seed; Microgel dispersion; Molecular characteristics; Monosaccharide composition; Rheology; Viscoelasticity.
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