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Modifying tyrosine crosslink formation in wheat dough by controlling innate enzymatic activity |
K. A. TILLEY, Grain Science & Industry Dept., Kansas State Univ., 313 Shellenberger Hall, Manhattan, KS 66506-2201 and M. Tilley, Grain Quality & Structure Research Unit, USDA-ARS-Grain Marketing & Production Research Center, 1515 College Ave., Manhattan, KS 66502-2736. Formation of the three-dimensional protein network known as "gluten" during dough mixing and breadmaking processes is extremely complex. It has been established that a specific subset of the proteins comprising the gluten complex, the glutenin subunits, directly affects breadmaking quality. Glutenin subunits have not been shown to exhibit any definitive structural differences that can be directly correlated to their ability to aggregate into the gluten complex and affect breadmaking quality. Evidence presented here indicates that tyrosine bonded species form in wheat doughs during the processes of mixing and baking and are major contributors to the structure of the gluten network. Various oxidizing and reducing agents that have been used in the baking industry directly affect tyrosine bonds. Tyrosine bonds between synthetic glutenin peptides form in vitro under baking conditions in the presence of potassium bromate and in the presence of water-soluble extract of flour. Bond structures and formation during breadmaking processes have been documented by HPLC, NMR and mass spectroscopic analyses. The formation of tyrosine crosslinks in developing wheat kernels has also been documented, shedding light on the biological mechanisms for tyrosine crosslink formation. Innate enzymes in the endosperm (flour) of wheat kernels have been isolated and characterized. Information regarding these enzymes and their ability to form dityrosine during breadmaking processes will be described. These enzymes and their functions provide necessary points of control during breadmaking processes.
Session 3, Control of endogenous enzymes in foods: A practical approach
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