Chemical and rheological properties of the beta-glucan produced by Pediococcus parvulus 2.6.
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.
Velasco
Susana E
SE
Departamento de Quimica Aplicada y Departamento de Ciencia y Tecnologia de Polimeros, Facultad de Quimica, Universidad del Pais Vasco, 20080 San Sebastian, Spain.
Areizaga
Javier
J
Irastorza
Ana
A
Dueñas
Maria T
MT
Santamaria
Antxon
A
Muñoz
María E
ME
D015394:Molecular Structure; D008970:Molecular Weight; D010376:Pediococcus / Q000737:chemistry* / Q000378:metabolism; D012212:Rheology; D047071:beta-Glucans / Q000737:chemistry* / Q000378:metabolism
D047071:beta-Glucans