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Shear Stress Relaxation of Native and Modified Potato Starch Gels
Author(s) -
Bohlin L.,
Eliasson A.C.,
Mita T.
Publication year - 1986
Publication title -
starch ‐ stärke
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.62
H-Index - 82
eISSN - 1521-379X
pISSN - 0038-9056
DOI - 10.1002/star.19860380405
Subject(s) - starch , viscoelasticity , potato starch , stress relaxation , phosphate , relaxation (psychology) , materials science , chemical engineering , chemistry , coating , polymer chemistry , composite material , organic chemistry , creep , psychology , social psychology , engineering
Abstract Shear stress relaxation measurements were used to characterize native potato starch gels, and modified gels, such as starch acetate, distarch phosphate, dihydroxypropyl distarch phosphate and lipid coated starch. It was found that cross‐linking and lipid coating greatly increased the stiffness of the gels, which was observed as increased relaxation modulus (G). These gels behaved like viscoelastic solids, which was observed as increased relaxation times (T½) and increased apparent residual moduls (G∞). During ageing, an increase in G and T½ as well as in G∞ was observed for the native starch, the starch acetate and the distarch phosphate. The hydroxypropoyl distarch phosphate and the lipid coated starch were very stable during ageing. To interpret the results in terms of the structure of the starch gel, the gel was described as a composite material, and the stress relaxation results were discussed according to a cooperative theory of flow.