Effect of Bran Reduction on Gluten Secondary Structure in Intermediate Wheatgrass (Thinopyrum intermedium) Dough

Thinopyrum intermedium, commonly known as intermediate wheatgrass (IWG), is a perennial crop with favorable agronomic characteristics. In comparison to wheat, IWG has higher protein and dietary fiber contents. However, the protein distribution is significantly different from that of hard red winter wheat. The difference in protein distribution coupled with higher fiber content negatively affects the dough rheology in terms of protein network formation. Therefore, the goal of this study was to determine the effect of bran reduction on the gluten secondary structure in IWG dough using ATR-FTIR spectroscopy. IWG grains sample was milled and bran was separated. Bran was added back to refined IWG flour at 100%, 75%, 50%, 25% and 0% of original bran content. Different flour samples were evaluated for dough strength using farinograph following the AACC method 54-21.02 at two temperatures 30\ub0C and 21\ub0C. Dough samples were collected at different time points during mixing: dough development time (DDT), stability departure, and overmixing, and were subjected to FTIR spectroscopy to determine changes in protein secondary structure. At 30\ub0C, IWG bran reduction did not cause significant structural changes in the dough made at DDT. At 21\ub0C, inclusion of bran caused partial dehydration of gluten giving more f-sheets at the expense of f-turns. Decrease of temperature in 100% IWG dough made at DDT resulted in more beta turns contributing to weaker dough. As mixing time increased, more f-sheets were formed at the expense of f-turns in the IWG dough possibly due to mechanical disruption of gluten network and formation of protein aggregates. Determining differences in gluten secondary structure as affected by bran content provides insights into gluten network formation and stability. This information leads to optimization of IWG grain processing in order to expand its market potential