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Molecular size and aggregation behavior of Erwinia gum in aqueous solution
Author(s) -
Zhang Lina,
Xu Xiaojuan,
Zhang Mei,
Chen Jinghua,
Meng Diya,
Ren Liwei,
Iijima Hideki
Publication year - 2000
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/(sici)1097-4628(20000222)75:8<1083::aid-app13>3.0.co;2-t
Subject(s) - aqueous solution , viscometer , chemistry , intrinsic viscosity , gel permeation chromatography , dynamic light scattering , molar mass , hydrodynamic radius , thickening agent , polymer , molar mass distribution , static light scattering , viscosity , arabinose , chromatography , polymer chemistry , chemical engineering , materials science , organic chemistry , xylose , thickening , polymer science , nanoparticle , fermentation , engineering , micelle , composite material
Abstract Erwinia (E) gum, a stabilizer and thickening agent of food, is composed of glucose, fucose, galactose, and glucuronic acid (1 : 0.1 : 0.05 : 0.3 by molar ratio). The apparent weight‐average molecular weight M w and intrinsic viscosity [η] in 0.2 M NaCl aqueous solution were measured to be 7.83 × 10 5 and 268 mL g −1 , respectively, by light scattering and viscometry. The aggregation behavior of E gum in aqueous solution was investigated by gel permeation chromatography (GPC) and dynamic light scattering. The results showed that 7.5% E gum exists as an aggregate, whose diameter is 12 times greater than single‐stranded chain, in aqueous solution at 25°C, and the aggregates' content decreased with increasing temperature or decreasing polymer concentration. The aggregates at higher temperature were more readily broken than in exceeding dilute solution. GPC analysis proved that a significant shoulder, corresponding to a fraction of higher molecular weight due to chain aggregation, appeared in the chromatogram of E gum in 0.05 M KH 2 PO 4 /5.7 × 10 −3 M NaOH aqueous solution (pH 6.0) at 35°C, and decreased with increasing temperature, finally disappeared at 90°C. The disaggregation process of E gum in aqueous solution can be described as follows: with increasing temperature, large aggregates first were changed into the middle, then disrupted step by step into single‐stranded chains. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1083–1088, 2000