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Rheological investigation of starch polysaccharide gelation
Author(s) -
Vorwerg Waltraud,
Radosta Sylvia
Publication year - 1995
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.19950990109
Subject(s) - starch , rheology , viscoelasticity , dynamic mechanical analysis , polysaccharide , materials science , aqueous solution , dynamic modulus , chemical engineering , rheometer , polymer chemistry , chemistry , composite material , polymer , organic chemistry , engineering
Small‐amplitude dynamic measurements of aqueous starch polysaccharide solutions are performed by a Bohlin controlled‐stress rheometer with air bearing. Three classes of starch polysaccharides–native starches, fractions of starches and hydrolysed starches–are compared in their molecular composition and rheological properties during and after the gelation process. Viscoelastic properties of solutions and gels are recorded in dependence on temperature and time, yielding storage and loss moduli during and after sol‐gel transition. Hot concentrated aqueous solutions are cooled down from 90 °C to 5 °C at a rate of 1 °C/min. Measurements are carried out at 0,1 Hz and 5% strain amplitude deformation. The typical course of the moduli of gelling starch polysaccharide solutions shows a liquid‐like behavior (G” > G') in the upper temperature level between 60 and 90 °C, a jumpwise increase with ensuing intersection of G' and G” below 60 °C and a solid‐like behavior (G' > G”) at lower temperatures with a slightly in time growing storage modulus. Storage and loss moduli depend on molecular composition and concentration of the substance. The process of starch polysaccharide aggregation is discussed with regard to theories of physical gelation by Ross‐Murphy and Winter.