Impact of intermediate wheat grass (Thinopyrum intermedium) on dough rheological properties

Intermediate wheat grass (IWG) (Thinopyrum intermedium) is a perennial grass with desirable agronomic traits and positive effects on environment. Attention is being given to incorporating genetic traits from IWG to common wheat because of its hardness and resistance to wheat diseases. However, the rheological performances of IWG blends with common wheat flour have not been investigated. In this study, IWG was blended with a commercial hard wheat flour (WF) at IWG:WF ratios of 0:100, 50:50, 75:25, 100:0. Mixing properties were evaluated by using a Farinograph. All the dough samples were prepared at constant water absorption (70%) that was optimal for WF to reach 500 BU. Gluten aggregation and pasting properties were also measured by using the GlutoPeak tester (GPT) and the Micro-ViscoAmylograph (MVAG), respectively. Addition of IWG resulted in a decrease in dough development time and an increase in consistency, likely due to the higher levels of fiber in IWG. However, the level of IWG in blends did not result in significant difference in dough development time or consistency. IWG-enrichment resulted in a significant decrease in dough stability, indicating weakening of gluten in the dough. Interestingly, 100% IWG was more stable during mixing compared to 50% or 75% IWG blends, which is probably due to the higher protein content of IWG, although its unclear if this attribute is directly related gluten proteins. Furthermore, GPT highlighted the ability of IWG proteins to aggregate and generate torque. Higher IWG enrichment resulted in faster gluten aggregation, however, with lower peak torque, suggesting weakening of WF gluten strength. MVAG data showed that IWG-enrichment increased the pasting temperature and decreased peak viscosity, probably due to the lower total starch content of IWG compared to WF. Further studies will investigate the suitability of IWG-blends to prepare baked-products with high protein and fiber contents.