Viscoelastic properties of highly concentrated maize starch solutions in DMSO
P.Ptaszek, M.Łukasiewicz, A.Ptaszek, M.Grzesik, J.Skrzypek, M.Kulawska
STARCH-STARKE, 63 (4), 181-189 (2011)
Abstract
Rheological measurements of highly concentrated dimethylsulfoxide (DMSO) starch solutions were performed. For all experiments commercial maize starch with different AM content was used. The research covered a wide range of polymer concentrations depending on linear fraction contribution and allowed to obtain a starch content up to 40% w/w. The analysis covered the time - concentration superposition method and fitting the continuous Maxwell model to the experimental data using Tikhonov regularization method. The results allowed statements about the viscoelastic behavior of non-aqueous starch solutions, depending on their molecular structure. If the linear AM is the predominant component of the starch, the system behaves more elastic compared to those composed of branched AP. The effect of variation in molecular constitution is stronger than the effect of concentration of the dispersion. Additionally, the molecular masses of both fractions seems not to be the crucial factor for rheological properties as well as biopolymer solubility in DMSO. Relaxation spectra obtained from Maxwell model show the drift of the main peak to shorter relaxation times when the concentration of biopolymer is rising. The phenomenon testifies about the influence of starch concentration on elastic response of the system.
