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The molecular basis of gluten structure and function. K. A. TILLEY (1), R. E. Benjamin (1), B. M.
Okot-Kotber (1), and O. M. Prakash (2). (1) Department of Grain Science and Industry, Kansas State
University; (2) Department of Biochemistry, Kansas State University.
For many years, the scientific literature has taught that disulfide bonds
were the only critical covalent crosslinks necessary for wheat flour dough formation. However, a different
molecular mechanism for dough formation has been discovered. Non-disulfide bonds, specifically tyrosine
crosslinks, which develop in wheat flour dough during the mixing and baking processes, are critical to the
formation of the gluten structure. Tyrosine crosslinks in flour and dough have gone unrecognized in the
past, likely due to the fact that many of the reagents and environments employed to study disulfide bonds
also affected tyrosine bonds. Direct evidence has been obtained indicating that these bonds play a
determinate role in the mixing and baking processes. Tyrosine bonds can form chemically under baking
conditions when synthetic glutenin peptides are used; however enzymatic mechanisms may also be involved
during gluten development in the dough environment. The tyrosine bond structure and its formation during
the breadmaking process have been documented by HPLC, NMR and mass spectroscopic analyses.
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