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Time‐dependent phenomena as evidence for structure‐forming properties of starches
Author(s) -
Ptaszek Anna
Publication year - 2014
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.201300113
Subject(s) - rheology , amylopectin , viscoelasticity , amylose , viscosity , starch , chemical engineering , shear rate , aqueous solution , materials science , scaling , thermodynamics , chemistry , composite material , organic chemistry , mathematics , geometry , physics , engineering
The study discusses the rheological properties of four different starches (amylose (AM), potato starch (P), waxy potato starch (WXP), and maize amylopectin (AP)) in the form of aqueous pastes and solutions in DMSO. Additionally, osmotic characteristics of diluted solutions of these starches are presented. The results of the qualitative hysteresis loop tests revealed that AM paste and AM solution in DMSO are rheologically stable fluids. Using the scaling of the concentration, it has been shown that the behavior of AM paste is complex. AP and WXP in form of pastes and their solutions in DMSO are rheologically unstable fluids. The course of the flow curves, carried out at the decreasing shear rate, indicates that AP paste accumulates energy. Equilibrium tests performed using AP paste, AP, WXP 1 and 5% solutions in DMSO showed a few interesting effects (chaotic behavior, oscillations, no change, small increase or decrease in apparent viscosity as a function of time). The nature of time‐dependent type phenomena, however, hinders the application of the Cheng and Evans viscosity theories to describe and model the rheological behavior. As the study results demonstrate, the rheological instability of the starch solutions is also based on the phenomena of energy accumulation, i.e. in viscoelastic effects.