Structural changes during starch pasting using simultaneous Rapid Visco Analysis and small-angle neutron scattering

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• 作者：James Doutch^a ; Mark Bason^b ; Ferdi Franceschini^a ; Kevin James^b ; Douglas Clowes^a ; Elliot P. Gilbert^a ; ^{elliot.gilbert@ansto.gov.au}
• 关键词：Starch ; Rheology ; Rapid Visco Analysis ; Small-angle neutron scattering ; Gelatinisation ; Pasting
• 刊名：Carbohydrate Polymers
• 出版年：2012
• 期刊代码：14_01448617
• 类别：ch
• 出版时间：15 April, 2012
• 卷：88
• 期：3
• 页码：1061-1071
• 文件大小：1570 K

摘要

Rapid Visco Analysis (RVA) is an industry-wide method extensively used for determining the viscous properties of starch slurries enabling information to be extracted on pasting properties; however little is known about structural changes that occur during standard protocols. A commercial RVA instrument was modified to allow the passage of a neutron beam through its heating block and paddle assembly to enable the simultaneous measurement of SANS and RVA on a variety of commercial starches. SANS measurements were made at 1 min intervals throughout a standard 13 min RVA process across a q range of 0.018-0.2 脜^鈭?. In each of the starches, the well-known lamellar structure was observed up to the point at which the viscosity began to increase markedly. At this stage, the lamellar structure transformed instantaneously; the scattering patterns are indicative of the formation of a large scale structure with no apparent semi-crystalline properties and whose spatial arrangement may be analysed in terms of a fractal-like gel. The basic building blocks of this gel, under the assumption that they are spheroidal, appear to have dimensions of approximately 1 nm across all the starches tested. The sizes of the aggregates formed are several times larger and were found to vary across the time course of the experiment.