Loehr, Leslie2024-01-192024-01-192023-10https://hdl.handle.net/11299/260113University of Minnesota M.S. thesis.October 2023. Major: Food Science. Advisor: Baraem Ismail. 1 computer file (PDF); xvi, 158 pages.Intermediate wheatgrass (IWG, Thinopyrum intermedium) is a perennial cereal grain capable of aiding the agricultural community in reducing the global environmental detriments of commercial agricultural practices. Factors such as soil erosion, lack of carbon sequestration, and nitrogen leaching are all current issues that need to be addressed with IWG potentially providing a sustainable solution. In addition to its environmental benefits, IWG provides ample nutritional advantages such as a relatively high protein, dietary fiber, and antioxidant content compared to one of the most ubiquitous cereal grains globally: wheat. However, a lack of understanding regarding on-going breeding program progress coupled with the absence of data on the storage stability post-processing of IWG grains contributes to little incentive for producers, processors, and consumers to focus on switching to this sustainable grain. Therefore, the objectives of this study were to: (1) screen 11 lines of IWG for differences in composition and enzyme activity as affected by breeding and agronomic practices, (2) determine the compounded impact of fat content, enzyme activity, and antioxidant content and activity on the storage stability of novel IWG cultivars and (3) identify the chemical changes induced by extrusion and germination of IWG grains and their impact on the storage stability of whole flours. Prior to treatment and storage, 11 samples of IWG were analyzed for proximate composition, protein profile, starch and total dietary fiber content, antioxidant content and activity, and enzyme activity utilizing AOAC and AACC standard methods. These results, primarily antioxidant content and activity, fat content, and enzyme activity, informed the selection of samples to be subjected to extrusion and germination treatments and subsequent ambient storage. Once selected, these samples underwent commonly used procedures for both extrusion and germination of cereal grains. Post-treatment and milling into whole flour, the samples were subjected to storage and analyzed periodically for carotenoid and hydroxycinnamic acid (HCA) content using high performance liquid chromatography, antioxidant activity using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and leucomethylene blue (LMB) assays (all at 0, 1, 3, 6, and 8 months of storage), lipase and lipoxygenase enzyme activity via a copper soap assay and ferrous oxidation-xylenol orange (FOX) assay, respectively (at 0, 3, 6, and 8 months of storage), free fatty acids and peroxide value content via AOAC titration methods (940.28 and 965.33, respectively; both at 0, 1, 3, 6, and 8 months of storage), and volatile odor compounds (VOC) via dynamic purge-and-trap followed by gas chromatography coupled with olfactometry and mass spectrometry analysis (GC-O-MS) at 0, 3, and 8 months of storage). The first commercial cultivar and the new IWG varieties continue to hold a strong nutritional advantage over hard red wheat (HRW), and all samples also contained relatively higher ferulic acid and lutein contents and had high antioxidant activity. Additionally, protein and total dietary fiber content was higher in IWG than in HRW. Variance among the samples was more strongly linked to genetic makeup rather than geographic growing location, confirming promise for individual cultivars to perform similarly regardless of agronomic effects. Based on their fat content, enzyme activity and antioxidant profile, MN1601-SYN2, MN1603-SYN3, and MN-Clearwater varieties were selected for extrusion and germination processing followed by 8 months of ambient storage. Extrusion caused complete inactivation of lipase activity, while germinated samples retained their lipase activity. Lipase activity was determined to be more influential to hydrolytic rancidity than fat content alone, giving an advantage to the extrusion process. The abundantly present antioxidants combated oxidative rancidity, with carotenoids playing a major role, as evidenced by the significant (P < 0.05) loss in lutein and zeaxanthin between 3-6 months of storage. This observed loss occurred at the same time as FFAs, PV, and VOC (primarily hexanal and 2-pentyl-furan) experienced abrupt increases. These findings are quite insightful for future IWG breeding progress. In addition, the work provided a comprehensive understanding of how common post-harvest processing affects the storage stability of IWG flour, an essential information to promote its use as a food ingredient.enExtrusionFlavorGerminationIntermediate wheatgrassPerennialStorage StabilityThesis or Dissertation