Publication no. C-1999-0216-05R |  VIEW ARTICLE

Use of the Rubber Elasticity Theory to Characterize the Viscoelastic Properties of Wheat Flour Doughs.

A-L. Leonard (1), F. Cisneros (1), and J. L. Kokini (1,2). (1) Cook College, Department of Food Science, Center for Advanced Food Technology, Rutgers, the State University, 65 Dudley Road, New Brunswick, New Jersey 08901-8520. (2) Corresponding author. Cereal Chem. 76(2):243-248. Accepted November 19, 1998. Copyright 1999 American Association of Cereal Chemists, Inc.

The viscoelastic properties of durum wheat flour doughs were measured using the extensigraph in uniaxial extension and the Rheometrics mechanical spectrometer in oscillatory shear. The research examined the effect of increasing density of cross-links on rubber elasticity in these systems. The stress-strain behavior of durum wheat flour dough was not well simulated by Mooney-Rivlin type nonlinear elasticity. Addition of increasing amounts of iodate made the dough show appreciable strain thickening behavior, approximating the behavior of natural rubbers The estimated apparent molecular weight between cross-links ranged from 10,500 to 16,000, much larger than that of rubbers, for which values are in the range of 500-1,000. When the Mooney-Rivlin equation was tested, it appeared to approximate only moderately well the extensional behavior of iodate-added wheat flour doughs at finite but low extensions, where the finite extensibility of chains is not a factor. It is hypothesized that the cross-linked network is highly diluted with hydrogen and hydrophobic bonds that limit the applicability of rubberlike elasticity theories. Increasing the cross-linked density using iodic acid developed matrices that moved the behavior of durum flour doughs closer to Mooney-Rivlin behavior.