title: Rheological and microstructural properties of the chia seed polysaccharide.
abstract: Chia seed polysaccharide (CSP) was extracted from chia (Salvia hispanica) seeds, and its rheological and microstructural properties in aqueous solutions were studied. CSP solution exhibited Newtonian and shear thinning flow patterns depending on shear rate when the concentration was ≤0.06% (w/v). CSP solutions at concentrations >0.06% (w/v) exhibited strong shear thinning behaviour within the shear rate tested (0.001-300s(-1)). The transition from dilute to semi-dilute regime occurred at a critical concentration (C*) of 0.03gdL(-1). The intrinsic viscosity was high (∼16dLg(-1)) and concentration dependence of zero shear viscosity in the semi-dilute regime followed η0∝C(2.7) relationship. The storage modulus (G') was higher than the loss modulus (G″) at all experimental frequencies and their frequency dependence was negligible at all tested concentrations. Apparent shear viscosity was smaller than dynamic complex viscosity at equivalent values of deformation and G' varied with the square of concentration indicating a gel-like behaviour in CSP solutions within 0.02-3.0% (w/v) concentrations. Controlled acid hydrolysis of purified CSP yielded various low molecular fractions with fairly uniform polydispersity giving a Mark-Houwink-Sakurada relationship of intrinsic viscosity equaling to 1.52×10(-4) (molecular weight)(0.803) (dLg(-1)).
authors.affiliation: School of Applied Sciences, RMIT University, Melbourne, VIC 3001, Australia; CSIRO Manufacturing Flagship, Clayton South, VIC 3169, Australia.
authors.forename: Yakindra Prasad
authors.initials: YP
authors.lastname: Timilsena
authors.affiliation: CSIRO Manufacturing Flagship, Clayton South, VIC 3169, Australia.
authors.forename: Raju
authors.initials: R
authors.lastname: Adhikari
authors.affiliation: School of Applied Sciences, RMIT University, Melbourne, VIC 3001, Australia.
authors.forename: Stefan
authors.initials: S
authors.lastname: Kasapis
authors.affiliation: School of Applied Sciences, RMIT University, Melbourne, VIC 3001, Australia; CSIRO Manufacturing Flagship, Clayton South, VIC 3169, Australia. Electronic address: benu.adhikari@rmit.edu.au.
authors.forename: Benu
authors.initials: B
authors.lastname: Adhikari
mesh_terms: D055119:Elastic Modulus; D008970:Molecular Weight; D011134:Polysaccharides / Q000737:chemistry*; D012212:Rheology; D027544:Salvia / Q000737:chemistry*; D012639:Seeds / Q000737:chemistry*; D033081:Shear Strength; D012996:Solutions; D013696:Temperature; D014783:Viscosity
chemical_list: D011134:Polysaccharides; D012996:Solutions
keywords: Chia seed polysaccharide; Critical concentration; Depolymerization; Intrinsic viscosity; Shear thinning