Technical Abstract:
Formation of the three-dimensional protein network known as "gluten" during dough mixing and breadmaking processes is extremely complex. 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.