35-4 |
Identification of novel structures in wheat dough: Impact on structure and function of gluten |
K. A. TILLEY, Grain Science & Industry Dept., Kansas State Univ., 313 Shellenberger Hall, Manhattan, KS 66506-2201 and M. Tilley, USDA-ARS-Grain Marketing Research & Production Center, 1515 College Ave., Manhattan, KS 66502. 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 the breadmaking processes have been documented by HPLC, NMR and mass spectroscopic analyses. Flours and doughs from other non-wheat grains have been examined for their abilities to form tyrosine crosslinks. Comparisons of tyrosine crosslinks in soft, hard and durum wheats have been made and show dramatic differences. The formation of tyrosine crosslinks in developing wheat kernels has also been documented, shedding light on the biological mechanisms for tyrosine crosslink formation. The relevance of these data to wheat quality will be discussed.
Session 35, Applications of proteomics to food science
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