Characteristics of Perennial Wheatgrass (Thinopyrum intermedium) and Refined Wheat Flour Blends: Impact on Rheological Properties

Intermediate wheatgrass (IWG) (Thinopyrum intermedium) is a perennial grass with desirable agronomic traits and positive effects on the environment. It has high fiber and protein contents, which increase the interest in using IWG for human consumption. In this study, IWG flour was blended with refined wheat at four IWG-to-wheat ratios (0:100, 50:50, 75:25, and 100:0). Samples were analyzed for proximate composition, microstructure features, pasting properties (Micro Visco-Amylo-Graph device), protein solubility, and total and accessible thiols. Gluten aggregation properties (GlutoPeak tester) and mixing profile (Farinograph-AT device) were also evaluated. IWG flour enrichment increased the pasting temperature and decreased the peak viscosity of blended flours. IWG proteins exhibited higher solubility than wheat, with a high amount of accessible and total thiols. The GlutoPeak tester highlighted the ability of IWG proteins to aggregate and generate torque. Higher IWG flour enrichment resulted in faster gluten aggregation with lower peak torque, suggesting weakening of wheat gluten strength. Finally, the addition of IWG to refined wheat flour resulted in a decrease in dough development time and an increase in consistency, likely because of the higher levels of fiber in IWG. The 50% IWG flour enrichment represents a good compromise between nutritional improvement and maintenance of the pasting properties, protein characteristics, and gluten aggregation kinetics

Rheological properties of perennial wheatgrass (Thinopyrum intermedium) and its blends with wheat flour

Intermediate wheatgrass (IWG) (Thinopyrum intermedium) is a perennial grass with desirable agronomic traits and positive effects on the environment. Its high fiber and protein contents have increased the interest in IWG for human consumption. As for improvement of IWG potential for food production, efforts are tied to understanding the functional properties of IWG. The aim of this study was to investigate starch physical properties and protein aggregation in IWG-only and IWG/hard wheat (HWF) systems. IWG-based doughs were prepared at 50%, 75% and 100% IWG levels in order to produce systems with total fiber content higher than 10%. The pasting properties of samples were evaluated using Micro Visco-Amylograph. Proteins in the various blends were characterized in terms of extractability, readily and SDS-accessible thiols. Gluten aggregation properties (using GlutoPeak) and mixing profile (using Farinograph) were also considered. IWG-enrichment increased the pasting temperature and decreased peak viscosity of blended flours. The former is related to the predominant presence of starch granules in IWG assembled together, whereas the latter to fiber content. IWG proteins were able to aggregate and form a gluten-like network that was less strong than HWF (GlutoPeak test). IWG-enrichment resulted in faster gluten aggregation and lower peak torque compared to HWF, suggesting a weakening of the gluten network. This is related to the high protein solubility of IWG. Moreover, despite the high level of thiol groups, these seem not to be as available for aggregating as in HWF. During mixing, IWG-enrichment resulted in an increase in consistency and a decrease in development time and dough stability, likely due to the higher levels of fiber and to differences in protein profile. The overall results suggest that 50% IWG-enrichment represents a good compromise between nutritional improvement and maintenance of the pasting properties, protein characteristics and gluten aggregation kinetics

Chemical characterization, functionality, and baking quality of intermediate wheatgrass (Thinopyrum intermedium)

Thinopyrum intermedium, known as intermediate wheatgrass (IWG), is one of several perennial crops available for potential food use. The overall objective of this work was to investigate the chemical, functional, and baking properties of wholegrain flour obtained from the grains of 16 IWG breeding lines. Compared to wholegrain wheat flours, IWG wholegrain flours had higher protein, dietary fiber, and ash, yet were lower in starch content and deficient in high molecular weight glutenins. The ratios of amylose to amylopectin among the wholegrain flours of IWG and wheat were similar, but IWG flours exhibited lower viscosity during heating and cooling. Dough from IWG flour had lower stability, resistance to extension and extensibility compared to dough from wheat flour. While bread from IWG flour had similar specific volume to one of the wheat flours, it had lower rising capability due to weaker gluten network forming ability. Although IWG flour might not be ideal for bread products that require rising properties, results indicated that it could be suitable for other applications. This work provided quality trait information that is useful for plant breeders in their effort toward the development of IWG lines for food use