title: Chemical and rheological properties of the beta-glucan produced by Pediococcus parvulus 2.6.
abstract: Some physicochemical and rheological properties of the exopolysaccharide (EPS) produced by Pediococcus parvulus 2.6 were examined. Structural characterization by NMR ((1)H and 2D-COSY) showed that the same EPS, a 2-substituted (1,3)-beta-D-glucan, was synthesized irrespective of sugar source used for growth (glucose, fructose, or maltose). The molecular masses of these beta-glucans were always very high (>10(6) Da) and influenced by the culture medium or sugar source. The steady shear rheological experiments showed that all concentrations of the beta-glucan aqueous solutions exhibited a pseudoplastic behavior at high shear rates. Viscoelastic behavior of beta-glucan solutions was determined by dynamic oscillatory analysis. A critical concentration of 0.35% associated with the appearance of entanglements was calculated. The beta-glucan adopts an ordered hydrogen bond dependent helical conformation in neutral and slightly alkaline aqueous solutions, which was partly denatured under more alkaline conditions.
authors.affiliation: Departamento de Quimica Aplicada y Departamento de Ciencia y Tecnologia de Polimeros, Facultad de Quimica, Universidad del Pais Vasco, 20080 San Sebastian, Spain.
authors.forename: Susana E
authors.initials: SE
authors.lastname: Velasco
authors.forename: Javier
authors.initials: J
authors.lastname: Areizaga
authors.forename: Ana
authors.initials: A
authors.lastname: Irastorza
authors.forename: Maria T
authors.initials: MT
authors.lastname: Dueñas
authors.forename: Antxon
authors.initials: A
authors.lastname: Santamaria
authors.forename: María E
authors.initials: ME
authors.lastname: Muñoz
mesh_terms: D015394:Molecular Structure; D008970:Molecular Weight; D010376:Pediococcus / Q000737:chemistry* / Q000378:metabolism; D012212:Rheology; D047071:beta-Glucans / Q000737:chemistry* / Q000378:metabolism
chemical_list: D047071:beta-Glucans