Determining food applications of intermediate wheatgrass: the association between grain chemistry and functionality in food systems

Abstract

Common wheat is a staple in diets around the world and is featured in a diverse variety of food products. Over the history of wheat cultivation, the climate has remained relatively stable, but in recent years the impacts of climate change are posing challenges to produce improved yields, while maintaining end-use quality. One method being explored in terms of diversifying food supply/products is supplementing traditional wheat-based products with a nutrient dense adjunct. Intermediate wheatgrass (IWG) is an ideal candidate for fortification as it possesses similar characteristics to common wheat, except for higher levels of protein and fiber, which is where the nutritional benefits are seen. IWG is also drought tolerant, better at scavenging nutrients left in the soil by previous crops and contributes to a more regenerative agricultural system due to its perennial nature. IWG has been studied for its potential as a fortifying flour in bread production but has been kept to relatively low levels of incorporation due to its imbalanced gluten profile. Therefore, the first chapter in the current study aimed to explore alternative food uses for IWG flour in flatbread, noodle, pasta, and cookie applications and determine what level of incorporation is ideal. IWG performed best at 25% incorporation for flatbread, 75% for noodles, 50% for pasta, and 50% for cookies. The differences in IWG flour composition, mainly its higher protein, lower starch, and higher fiber content, all played a role in the functionality of the flour and impacted to the end product rheological properties. Incorporation of IWG into wholemeal common wheat formulations decreased the release of glucose over time during in vitro digestion, suggesting that IWG incorporation may aid in reducing the glycemic load of traditionally carbohydrate rich products. Protein digestibility varied between products, but there were no significant differences between types of flour used. All samples had high in vitro protein digestibility, and further studies that more closely imitate the human digestive system are warranted to obtain a better understanding of if IWG affects protein digestibility. The second chapter’s aim is to determine the protein characteristics and identify what sets it apart from common wheat. IWG is deficient in high molecular weight glutenin (HMWG), which plays a key role in gluten development by facilitating protein-protein interactions via disulfide bonds. A closer look at the molecular weight distribution of functional unextractable HMWG shows that IWG has some HMWG present but is lacking compared to common wheat. IWG also has a gliadin fraction significantly higher to common wheat and is high in globulins and albumins which is expected due to the smaller seed size and therefore greater bran to endosperm ratio. There is some HMWG present in IWG, with some similar HMWG subunits, such as Dx5, being found in both IWG and CWRS, among other HMWG subunits. IWG currently has the potential to be used in applications such as flatbread and tortillas where a strong gluten network isn’t necessary for high product quality. IWG has the potential to develop a functional gluten composition through selective breeding efforts and has the potential to provide flours for a multitude of end use applications.