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Linear viscoelastic properties of dough, gluten and glutenin from durum and common wheat: A polymer
science interpretation of the molecular basis for strength. S. J. MULVANEY (1), J. E. Dexter (2), and
N. M. Edwards (2). (1) Department of Food Science, Cornell University, Ithaca, NY; (2) Grain Research
Laboratory, Canadian Grain Commission, Winnipeg, MB.
From a polymer science perspective, gluten is a highly complex
material which contains elements of several distinct polymer classes. This makes it difficult to relate its
physical material properties to any one underlying molecular structure, such as entanglements. A reasonable
physical model of gluten is that of an elastomeric polymer fraction (glutenin) plasticized, or at least
compatibilized, by a gliadin/water resin, and possibly lipids as well. However, the glutenin protein fraction
itself appears to have a very broad molecular weight distribution as inferred from SE-HPLC results, and its
viscoelastic properties are clearly influenced by the many types of physical crosslinks (disulfide, hydrogen,
ionic and hydrophobic bonds, or interactions) present in glutenin. Thus, glutenin may be similar to polymer
gels containing both physical crosslinks and entanglements such as ionomers. To test this supposition we
determined the linear viscoelastic properties (LVP) of glutenin, gluten and dough obtained from a number
of durum and common wheat cultivars of variable strength, as defined by mixing requirement and dough
elasticity. The results indicated that the contribution of long relaxation times to the LVP increased for
materials obtained from stronger cultivars. These results are interpreted in conjunction with SE-HPLC data
for these same cultivars and in the context of polymer-based physical gels, to better understand the
molecular basis for strength across both durum and common wheat cultivars.
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