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Title: SHEAR-THICKENING AND FLOW-INDUCED STRUCTURE IN A SYSTEM OF DMSO CONTAINING WAXY MAIZE STARCH

Author
item Dintzis, Frederick
item BAGLEY, EDWARD - ARS (RETIRED)
item Felker, Frederick

Submitted to: Journal of Rheology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/24/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary: Starches are dissolved before they are used in food or industrial applications. Thus, the behavior of different starches as they are dissolved is important in processing technology and in using starches for specific purposes. This study shows that when one type of corn starch, waxy maize, is gently dissolved it forms structures in the liquid and the liquid flows differently than if normal corn starch were dissolved in it. However, if waxy maize starch is dissolved in a harsh manner the structures do not form and the solution flows like solutions of normal corn starch. This difference in behavior between the two dissolved starches is important to starch processors for both food and industrial applications because it provides a new basis for understanding and controlling processing methods that affect the properties of various dissolved starches and their products.

Technical Abstract: Waxy maize starch in the solvent 90%DMSO-H2O exhibited the phenomena of dilatancy, quasi-hysteresis loops of shear stress versus strain rate that were anticlockwise and flow-induced structure that was observed with phase contrast microscopy. Normal maize starch and an enriched fraction of normal maize amylopectin did not. The ability of a waxy maize starch sample to have these properties could be destroyed by severe treatment. W consider the flow properties of dilatancy and anticlockwise shear stress/strain rate loops to be indicative of a flow-induced structure that occurs with waxy maize starch amylopectin. Because these effects do not occur with normal maize starch we infer that there is a significant difference between the amylopectins of waxy maize starch versus normal maize starch.