Browsing by Subject "Intermediate wheatgrass"

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    Chemical Characterization, Functionality, and Baking Quality of Intermediate Wheatgrass (Thinopyrum intermedium)
    (2017-05) Rahardjo, Citra
    Environmental problems have exacerbated the challenges of food production. Soil erosion, run-off from irrigation, and greenhouse gas emissions have significantly impacted the ecosystem through their cumulative effects over decades. As the population increases, these aforementioned problems will grow in scale and scope. Thus, it is important to address these concerns by investigating sustainable solutions and conducting research on new approaches to food supply. Specifically, the development of perennial crops for food use would have environmental benefits such as reduced soil and water erosion. Further, the usage of perennial crops for food applications would provide alternatives to the current and ever diminishing food supply, provide incentives to farmers for planting these crops, and address consumers’ growing interest in sustainable food systems. One of several perennial crops available for potential food use is intermediate wheatgrass (IWG) (Thinopyrum intermedium). Little is known about the chemical and functional characteristics of IWG. Therefore, the overall objective of this work was to characterize the chemical and functional properties of IWG grains from multiple breeding lines for food applications, namely bread baking. Sixteen IWG experimental lines along with one bulk IWG sample and two wheat controls (Arapahoe and commercial hard red wheat) were analyzed for proximate composition following standard methodologies. Dietary fiber, total starch content, and percent damaged starch were determined using Megazyme kits. Amylose/amylopectin ratio and their molecular weight distribution were determined using size exclusion chromatography. Gluten forming proteins profile and molecular distribution were determined using gel electrophoresis and size exclusion chromatography. Dough rheology was assessed using a farinograph and a texture analyzer equipped with a Kieffer rig, while starch pasting properties were monitored using a rapid visco analyzer. Bread baking tests were performed following the AACCI 10-10.03 method. Compared to wheat controls, IWG samples had higher protein, dietary fiber, and ash contents, yet were lower in starch content and deficient in high molecular weight glutenins (HMWG), important protein components responsible for dough strength and elasticity. Specifically, wheat controls had more high molecular weight polymeric proteins (HMWPP), while IWG samples had more albumins and globulins. The ratios of amylose to amylopectin among the IWG samples and the wheat controls were similar. However, percent damaged starch was higher in the wheat controls than in IWG samples. On the other hand, the soluble to insoluble dietary fiber ratio was higher in wheat controls than in IWG samples. Dough rheology data showed that IWG dough was weaker than that of the controls. Farinograph and Kieffer data demonstrated that doughs made from wheat controls were more stable, more resistant to extension, and more extensible than doughs made from IWG samples. In terms of starch pasting properties, wheat controls had higher peak, hold, and final viscosities than the IWG samples, indicating the superiority of wheat controls over IWG samples as viscosity builders. The starch pasting properties data illustrated the samples’ behavior upon heating and cooling treatments, which are important characteristics to consider when evaluating IWG for commercial applications. Even though IWG had similar specific volumes to one of the wheat controls (hard red wheat), both wheat controls had a higher rising capability due to the wheat’s gluten network forming ability. Deficiency in HMWG and high fiber content of IWG samples, contributed to the poor gluten network and consequently inferior baking quality. Overall, results of this work suggest that IWG has a superior nutritional profile as compared to wheat, but poses challenges for baked products that require dough rising properties. Further studies on IWG, such as investigating the effect of conditioners on enhancing protein functionality, determining the effect of fiber on dough development, effect of blending with wheat, and exploring other food applications would enhance its potential utilization as a food crop. This research and future efforts will support breeders in their current screening and future breeding efforts for the development of IWG lines suitable for food applications.
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    Effects of Bran Content, Thermal Treatment, and Storage on Flavor Development and Functionality in Intermediate Wheatgrass Flour
    (2020-01) Luu, Misen
    Intermediate wheatgrass (IWG, Thinopyrum intermedium) is a perennial crop that has garnered attention for its environmental and nutritional benefits. Selected as a promising candidate among other perennial crops for food use, IWG has good flavor, breeding potential, and superior environmental benefits due to its extensive root system and long growing season. Understanding the storage stability of IWG will further improve its likelihood of integration into the food market. Grains, including wheat, are typically processed into flour and stored until use. Grains can be stable for up to 8-12 years; however, flour has a significantly lower shelf-life. While the storage stability of IWG groats has been investigated, the storage stability of IWG flour have not yet been addressed. Thermal treatment may be used to increase grain shelf life by inactivating enzymes that are involved in lipid rancidity, which is a major pathway for the formation of odor active volatile odor active compounds (VOAC). On the other hand, thermal treatment may negatively impact functionality over storage. Reducing the bran content may also increase shelf life by reducing fat content; however, it would be at the expense of reducing the dietary fiber content. Understanding the storage stability of IWG and identifying methods to improve its stability will not only enhance commercialization potential, but will also incentivize farmers to plant IWG. The objectives for this research study were to: (1) Evaluate the effects of prior grain storage, bran content, and steam treatment on the development of flavor in IWG flour over storage at 43% relative humidity and (2) Evaluate the effects of prior grain storage, bran content, and steam treatment on the functionality of IWG flour over storage at 43% and 65% relative humidity. Prior to storage, compositional analysis of IWG and hard red wheat (HRW, control), from two growing seasons, were carried out following official AOAC and AACCI methods. IWG groats were subjected to steam treatment directly above a boiling water bath at 100°C for 2 minutes. After equilibration at room temperature for 24 hours, IWG groats were milled into refined, partially refined (75% bran), and whole flour, while HRW groats were milled into whole and refined flour. Flour samples were stored at ambient temperature at 43% and 65% relative humidity (RH) for up to 9 months of storage. Samples were analyzed periodically for changes in flavor and dough functionality. VOACs were extracted from flour following a dynamic headspace purge and trap protocol and analyzed by gas chromatography-olfactory-mass spectrometry. VOACs were measured at the beginning, middle, and end of storage. A descriptive analysis was used to document the nature and extent of differences in sensory properties and was conducted with eight trained sensory panelists to describe differences in aroma, flavor, taste, and aftertaste in tortillas made from the stored flour. Dough functionality was measured every 3 months of storage. Rheological and mixing properties were measured using a Farinograph® and a texture analyzer equipped with a Kieffer rig. Gluten strength was measured using Brabender® GlutoPeak. Starch pasting profile was analyzed by Micro-Visco-Amylograph®. IWG had significantly higher protein, insoluble fiber, total dietary fiber, and fat content than HRW. The steam treatment employed resulted in a significant decrease in lipase and LOX activity, without significantly reducing antioxidant content. Over storage, identified odor active VOACs included alkyl and enal aldehydes, alcohols, and furans, which are products of lipid oxidation. By the end of storage, whole IWG flour showed significantly greater intensity of nearly all identified VOACs, such as pentanal, hexanal, 1-octen-3-ol, and 2-pentylfuran, in comparison to HRW flour. However, due to IWG’s higher antioxidant content, the induction period of VOACs in IWG was longer than that of HRW, indicating better short term storage stability. IWG was described as grassier and earthier compared to HRW, due to the presence of alkyl aldehydes, 2-pentylfuran, and 1-octen-3-ol. Steaming resulted in significantly lower intensities of VOACs, attributed to a reduction in enzyme activity. Partial refinement also resulted in a significant reduction in the intensity of VOACs. IWG had more earthy, grassy and Play-Doh® aromas, and higher intensities of peanut butter and beany flavor than HRW samples. IWG had greater intensity rating of flavor and the five basic taste (sweet, salty, bitter, sour, and umami) and aftertaste than HRW samples. Samples with lower bran content had lower overall flavor, bitter and salty taste, and overall aftertaste. Steamed IWG samples had lower overall aroma, flavor and aftertaste compared to not-steamed IWG samples. IWG flour had increases in dough development time, stability, resistance to extension, and gluten aggregation over short term storage, indicating an increase in dough strength. IWG also had improvement in starch pasting properties over storage, including peak, hold, and final viscosity. Partial bran refinement resulted in better dough functionality and starch pasting properties due to less interference of the fiber with the formation of the gluten network and a higher starch to non-starch ratio, respectively. Steaming resulted in higher dough development time and resistance to extension but had a slightly negative impact on starch pasting viscosity values. Partial refinement of IWG resulted in lower intensities of off-odor flavor compounds, lower sensory attributes ratings, and improved functionality, while maintaining the nutritional benefits associated with the bran. The interruption of enzymatic activity by steam treatment helped off-set unfavorable flavor development, thus could be used to prolong the shelf-life of IWG flour. Together, these two processing practices make IWG viable for commercial use.
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    Evaluating Crop Physiological and Stand Age-Related Controls Over Soil Carbon and Nitrogen Dynamics In Perennial and Annual Grains
    (2023-05) Woeltjen, Stella
    Little is known about how the cycling of carbon (C) and fertilizer nitrogen (N) between crop tissues and soil pools is expressed in perennial grains such as intermediate wheatgrass (IWG, Thinopyrum intermedium (Host) Barkworth and Dewey), and whether these processes change within a growing season and across IWG stand age. To evaluate these ideas, we established three studies to quantify 1) root growth and decomposition, 2) C uptake and partitioning to crop-microbial-soil pools, and 3) N sources and N conservation in first-year IWG (IWG-1), second-year IWG (IWG-2), third-year IWG (IWG-3) and annual wheat (Wheat). These studies illuminated age-related changes in IWG root growth and decomposition, and C uptake and partitioning. In the 0 – 15 cm depth interval, IWG-1 new root growth was 1.7 times greater than that of IWG-2, and IWG-1 (14 – 17%) retained significantly more new C in roots than IWG-2 (6%) at the time of peak new C recovery. Conversely, IWG-2 root decomposition and utilization of new C by saprotrophic fungi was significantly greater than that of IWG-1, with the proportion of new soil microbial biomass C recovered from saprotrophic fungi increasing from 30% to 40% between IWG-1 and IWG-2. Together, these results indicated IWG transitioned from a system dominated by belowground C inputs and new root growth to one dominated by the loss of belowground C via root decomposition and heterotrophic decomposition across the first two years following establishment, in line with a system transitioning from an acquisitive to conservative growth strategy. The transition to a system dominated by the decomposition of belowground root inputs suggests IWG may develop a greater capacity for recycling N from root tissues to inorganic soil N pools, thereby lessening the need for external fertilizer N inputs. However, the proportion of tissue N sourced from fertilizer increased between the first and third IWG production year, suggesting reliance on fertilizer N increases with stand age. Optimizing IWG N management recommendations to adequately meet IWG N demands will be critical to reducing reliance on external fertilizer inputs and ensuring IWG remains a profitable and sustainable alternative to annual grains in agricultural landscapes.
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    Evaluation of the Chemical and Functional Stability of Intermediate Wheatgrass (Thinopyrum intermedium) over Storage and in Response to Steam Treatment
    (2018-12) Mathiowetz, Amy
    Annual crop farming is degrading the environment at a faster rate than it can be restored, causing soil erosion and water run-off with subsequent loss of nutrients and biodiversity. Yet, the world population currently relies on annual cereal grains to supply 40% of their calorie needs and 60% of their protein needs. The high dietary demand for cereal grains, together with the high rate of soil degradation from annual farming and growing consumer interest in sustainably-sourced food creates space in the market for a more sustainable grain. Perennial intermediate wheatgrass (IWG), Thinopryum intermedium, is a promising grain to fulfill this role, owing to its good flavor, breeding potential, and superior environmental benefits due to its extensive root system and long growing season. Understanding the storage stability of IWG and identifying ways to improve its stability will not only help incentivize farmers to plant IWG, but will also help make IWG competitive against existing grains on the market. The objectives of this study were: (1) evaluate the effect of steam treatment on antioxidant content and activity, enzyme activity, and progression of hydrolytic and oxidative rancidity in IWG compared to hard red wheat (HRW) over storage at different temperatures; (2) evaluate the effect of steam treatment of IWG grains on the functionality of its whole flour over storage at different temperatures; (3) determine the overall safety of the grains by assessing presence of chemical residues, such as pesticides and mycotoxins, heavy metals, allergens, and anti-nutrient factors. Pre-storage, compositional analysis of IWG and HRW was carried out following official AOAC and AACCI methods. Steam treatment was carried out by subjecting 30 g aliquots of IWG and HRW groats to 100°C and 95% relative humidity conditions in a proofing oven for 60 minutes. Steamed and non-steamed samples were stored at 45°C, ambient (22 ± 2°C), and 4°C at 0.43 water activity for 6 weeks, 6 months, and 12 months respectively. Samples were analyzed periodically for lipoxygenase and lipase activity, hydroxycinnamic acid content, carotenoid content, antioxidant activity, and indicators of hydrolytic and oxidative rancidity, including free fatty acids and hydroperoxides, respectively. Lipoxygenase activity pre- and post-steam treatment was analyzed using the ferrous oxidation-xylenol orange (FOX) assay, and lipase activity was determined spectrophotometrically using a copper soap assay. Hydroxycinnamic acids and carotenoids were quantified using high performance liquid chromatography. Antioxidant activity pre- and post-steam treatment was analyzed using 1,1-Diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging and leucomethylene blue (LMB) assays. Free fatty acids and hydroperoxides were quantified according to AOAC titration methods 940.28 and 965.33, respectively. Functionality parameters were also measured at the beginning, middle, and end of storage at each storage temperature. Rheological and mixing properties were assessed using a Farinograph® and a texture analyzer equipped with a Kieffer rig. Starch pasting properties were monitored using a MicroVisco-Amylograph®. Bread baking tests were performed according to AACCI 10-10.03 method. IWG had significantly higher protein, insoluble fiber, and fat content than HRW, along with a higher lipase activity. HRW had a relatively higher lipoxygenase activity than IWG. IWG also had significantly higher hydroxycinnamic acid and carotenoids concentrations than HRW, along with higher antioxidant activity. The steam treatment employed in the present study did not inactivate lipoxygenase and lipase. Throughout storage, lipase activity significantly decreased in non-steamed grains over ambient (22 ± 2°C) storage but otherwise was retained over accelerated (45°C) and refrigerated (4°C) storage. However, an after-ripening effect was evident in lipoxygenase activity at ambient and 45°C temperatures, with significant increases in activity over storage. Hydroxycinnamic acid content was retained throughout storage, with prolonged storage inducing increases to its content, as well as increases to antioxidant activity at higher storage temperatures. Carotenoid content decreased throughout storage in IWG and HRW, to a greater degree at higher storage temperatures, as was expected due to its high susceptibility to oxidation. Development of oxidative and hydrolytic rancidity in IWG was minimal throughout storage of groats. Although the steam treatment was not able to effective in inactivating enzymes, it demonstrated a minimal, but positive effect on antioxidant activity and content, as well as a slight inhibitory effect on hydroperoxide formation over storage. IWG demonstrated a significantly higher antioxidant content and antioxidant activity and lower hydroperoxide content than HRW throughout storage. In terms of hydrolytic rancidity, IWG showed higher lipase activity and free fatty acid concentration than HRW throughout storage. IWG showed increases to dough development time, resistance to extension, and loaf volumes over storage, denoting an increase in dough strength, although no significant increases to dough stability time were evident. IWG also had improvements to starch pasting viscosities over storage, including peak viscosity and hold viscosity, at all temperatures. The effects of steaming on functionality were temperature-dependent, with positive effects on dough development time and resistance to extension during storage at 45°C and improvements to starch pasting viscosities during storage at ambient temperature. Steaming appeared to have a negative impact on functionality at refrigerated storage temperatures. Steaming did not have an effect on bread loaf volumes of IWG over storage. Although overall functionality of IWG remained inferior to HRW throughout storage, HRW had significant decreases in several functionality parameters over storage. While steaming had a positive effect on some of these parameters (e.g. extensibility, loaf volume), it had a negative impact on others (e.g. starch pasting viscosities). Bread firmness was not significantly affected over storage in either grain. The present study was the first to evaluate the storage stability of IWG and investigate steam treatment as a mode of improving storage stability of IWG. The results of the study provide additional incentives to farmers and food manufacturers alike by highlighting IWG’s competitive storage stability. The present study demonstrated not only its high tolerance to storage but in some regards, its positive response to storage. Furthermore, this research formed the foundation for establishing a more effective method of steam treatment in a currently ongoing storage study on IWG flour.
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    Impact of Processing on the Physicochemical and Nutritional Properties of Intermediate Wheatgrass (Thinopyrum intermedium) and Wheat (Triticum sp.)
    (2022-11) Boakye, Prince
    Annual cereal grains are a major part of the human diet. However, their cultivation is less sustainable and is associated with environmental issues such as soil erosion and emission of greenhouse gases into the atmosphere. Cultivating perennial grain crops to supplement these annual grains offers a promising approach to reducing these environmental issues while providing food for the ever-growing human population. To this end, intermediate wheatgrass (IWG), a perennial grain crop, is being developed and explored for mainstream food applications. The first part of this dissertation explored extrusion cooking of IWG for the first time to produce expanded IWG that could be used as snacks and breakfast cereals. First, we optimized the extrusion conditions for the production of expanded IWG. In that work, the effects of extrusion conditions including feed moisture content (20, 24, and 28%), screw speed (200, 300, and 400 rpm), and extrusion temperature (130, 150, and 170 °C) on the physical and functional properties (moisture content, expansion ratio, bulk density, hardness, water absorption index (WAI), water solubility index (WSI)) of IWG were investigated. Response surface methodology (RSM) was used to model and optimize the extrusion conditions to produce expanded IWG. The model coefficient of determination (R2) was high for all the responses (0.87 – 0.98). All the models were found to be significant (p < 0.05) and were validated with independent experiments. Generally, all the extrusion conditions were found to have significant effects on the IWG properties measured. Increasing screw speed and decreasing the extrusion temperature resulted in IWG extrudates with high expansion ratio. This also resulted in IWG extrudates with generally low hardness and bulk density. Screw speed was found to have the most significant effect on water absorption index (WAI) and water solubility index (WSI), with increasing screw speed resulting in a significant (p < 0.05) decrease in WAI and a significant (p < 0.05) increase in WSI. The optimum conditions for obtaining an IWG extrudate with a high expansion ratio and WAI were found to be 20% feed moisture, 200 – 356 rpm screw speed, and 130 – 154 °C extrusion temperature. Then, these optimum conditions were used to produce two expanded IWG products (extrudates I and II), and the physicochemical and nutritional properties of these products were characterized, comparing them to raw IWG flour. We observed that extrusion resulted in slight decreases in dietary fiber, fat, starch, and amylose contents of IWG, whereas protein and ash contents did not change. A significant increase in starch damage after extrusion led to significant increases in starch digestibility and hydration properties of IWG. Correspondingly, slowly digestible starches and resistant starches were significantly reduced after extrusion. Pasting profile studies showed significant decreases in all pasting parameters measured except for breakdown viscosity after extrusion. Higher antioxidant activity and phenolic acid levels, mainly due to ferulic acid, were observed even after extrusion. However, carotenoid content decreased significantly (up to 65.8% reduction in lutein and 50.4% reduction in zeaxanthin). These findings provide useful information on the production of expanded IWG using extrusion cooking. This is critical in the efforts to increase the demand and marketability of IWG. Furthermore, we have shown that extrusion cooking can improve the antioxidant activity and maintain high protein and dietary fiber levels in IWG, but it may not be suitable for preserving carotenoids in IWG.In the second part of this dissertation, we aimed to address an issue with the consumption of wheat, an annual grain that is a major staple worldwide. Wheat provides nearly 20% of calories and protein in the human diet. However, fermentable oligo-, di-, and monosaccharides and polyols (FODMAPs) and amylase/trypsin inhibitors (ATIs) present in wheat flour can trigger irritable bowel syndrome (IBS) and non-celiac wheat sensitivity (NCWS) symptoms in some individuals. This has negatively affected the demand and consumption of wheat in recent years. Thus, reducing FODMAPs and ATI concentrations in wheat flour could make the grain accessible to humans with IBS or NCWS. To this end, we first evaluated a diverse panel of heritage and modern spring wheat lines (208 lines in total) grown in two locations in Minnesota (Crookston and Saint Paul) for FODMAPs and ATI levels and carried out a genome-wide association analysis to identify markers associated with wheat FODMAPs and ATIs. The discovery of such markers, in conjunction with a genome-wide selection strategy, could aid in the selection of breeding lines with lower levels of FODMAPs and ATIs. FODMAPs and ATIs were quantified using High-performance anion-exchange chromatography (HPAEC) and High-performance liquid chromatography (HPLC), respectively. A strong population structure was observed, as the first principal component axis alone explained a third of the genotypic variation, and lines clustered into three distinct clusters of einkorn, emmer, and modern wheat lines. Trait correlations (r) were low to moderately high, ranging from 0.06 - 0.54. Broad-sense heritabilities ranged from low to medium (0.18 - 0.55). Association analysis resulted in the detection of 36 quantitative trait loci (QTL) in 15 chromosomes which were distributed in 30 unique genomic regions based on haplotype analysis; five of the 36 QTL were shared among two to four traits. The QTL were of small to medium effect as the range of explained phenotypic variation was 6.4% - 10.5%. There was no overlap among the QTL regions reported in this research compared with those reported in previously published studies. Genomic prediction models predicted the traits with low to moderately strong correlations (r = 0.23 - 0.49). We also investigated the effect of type I sourdough fermentation (4- and 12-h fermentation times) on the FODMAP and ATI levels in twenty-two wheat lines selected from the lines used in the genetics study based on availability and the initial levels of these compounds. We observed that FODMAPs and ATIs were significantly influenced by variety as well as growing location. Longer sourdough fermentation time (12 h) caused up to 69%, 69%, and 41% reductions in fructans, raffinose, and ATIs, respectively, in the resulting sourdoughs. However, a substantial increase in mannitol (550%) was observed after sourdough fermentation. These findings suggest that in type I sourdough fermentation, mannitol production should be monitored, and strategies to reduce its level in the fermented product should be considered.
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    PERENNIAL FUEL, FEED, AND CEREAL: HIGH DIVERSITY PERENNIALS FOR BIOFUEL AND INTERMEDIATE WHEATGRASS FOR GRAIN AND FORAGE
    (2019-12) Dobbratz, Michelle
    Perennial crops may counteract negative effects of annual agriculture, such as carbon emissions, water pollution, and erosion, and systems are being developed that supply fuel, feed, and cereal. One source of fuel is cellulosic ethanol from perennial sources, and one source of feed and cereal is intermediate wheatgrass. Regarding cellulosic ethanol, markets are not currently supported by policy, making adoption of these systems largely a matter of carbon storage benefit. Regarding intermediate wheatgrass, little is known about its nitrogen balance and reproductive morphology, complicating long-term management. In the perennial cellulosic ethanol system, I measured aboveground biomass, change in total soil C, soil microbial biomass, and extracellular enzyme activity with and without nitrogen in four species mixture treatments ranging from 1-24 native species at four sites across Minnesota. I found no overall trends, possibly due to variation across sites or due to minimal management over the 12 years since establishment. Over time, soil carbon increased in the shallower depths at one site and decreased in the deeper depths at two sites. I measured plant, tiller, and rhizome densities in plants from sown seed, vegetative propagation, or seed shatter at four sampling times in 1 year old and 2 year old intermediate wheatgrass stands. Tiller density was similar in both stands, but rhizome and propagule densities were greater in the 2 year old stand. Likely, tiller replacement and death rates are equal, but vegetative propagation increases between years, increasing plant population, possibly leading to competition and affecting long-term yield. Also in intermediate wheatgrass, I measured nitrogen in shoot, root, and grain tissue along with soil mineral and mineralized nitrogen in three nitrogen treatments (80 kg N ha-1 in spring, 40-40 kg N ha-1 in spring and summer, and unfertilized control) at four sampling times in 1 year old and 2 year old stands. The spring treatment had greater root nitrogen, but it also had greater lodging. The late fall sampling had the greatest soil nitrogen, and since soil mineral N was low at that time there was likely an influx of organic nitrogen, likely due to root turnover.
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    Phenotype and SNP marker data for an intermediate wheatgrass (Thinopyrum intermedium) nested association mapping (NAM) population evaluated in St. Paul, MN and Salina, KS in 2017 and 2018
    (2021-06-21) Altendorf, Kayla R; DeHaan, Lee R; Anderson, James A; Larson, Steven R; kayla.altendorf@usda.gov; Altendorf, Kayla R; University of Minnesota Wheat Breeding Lab
    An intermediate wheatgrass (Thinopyrum intermedium) Nested Association Mapping (NAM) population was evaluated at the University of Minnesota Agricultural Experiment Station in St. Paul, MN and The Land Institute in Salina, KS for two years (2017 and 2018). The population (n = 1,168 with both phenotype and genotype data) consisted of ten families where each progeny shares one common parent and was planted in a RCBD design with two blocks surrounded by a border plant. The phenotypic dataset includes 33 traits ranging from morphological, maturity, yield components and domestication traits, and a note column which indicates whether the plants were later identified as selfs and/or other observations. The genotype data was derived from genotyping by sequencing and includes over 8,000 SNP markers. The consensus genetic map was created in JoinMap and used for linkage mapping both within and combined across populations.
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    Phenotypic And Genetic Characterization Of Domestication And Yield Component Traits In The Perennial Grain Crop Intermediate Wheatgrass
    (2020-04) Altendorf, Kayla
    Chapter 1 Perennial plants provide extensive environmental services, and increasing their prevalence on the agricultural landscape is one way to improve sustainability. Direct domestication of intermediate wheatgrass (Thinopyrum intermedium) as a perennial grain crop is underway, and selection has focused primarily on improving seed size and yield. Breeders are limited by the lack of understanding of yield and its relationship with component traits in this species. We characterized a large population (n = 1168) of IWG spaced plants in St. Paul, MN and Salina, KS in 2017 and 2018 for a series of 13 yield component traits. Family by environment by year interaction was highly significant (P < 0.001) for all traits, indicating that family performance and rankings were variable across environments. In year two in St. Paul, yield plant-1 and reproductive tiller numbers nearly doubled, while all other yield components, including yield spike-1, thousand grain weight, spikelets spike-1 and florets spikelet-1 significantly decreased. Bivariate correlation analyses between component traits revealed consistent trends across environments and highlighted positive associations of seven traits with grain yield. Structural equation modeling (SEM) was conducted using an initial path model that more clearly delineated relationships into direct and indirect effects. When yield is measured on a yield spike-1 basis, floret site utilization was the primary contributor to yield, followed by spikelets spike-1, florets spikelet-1 and thousand grain weight. When measured on a plant-1 basis, reproductive tiller number was the most significant contributor to yield in all environments. Considering the limited indirect effects of biomass and maturity component traits, and the potential for strong indirect selection for tillering when selecting for yield plant-1, we suggest a two-step selection procedure on yield spike-1 and floret site utilization and explored alternative methods for collecting data on this labor-intensive trait. Future work should test the predictive ability of yield spike-1 and floret site utilization in IWG spaced plants and seed production swards. Chapter 2 Intermediate wheatgrass (IWG) is an outcrossing, cool season grass species currently undergoing direct domestication as a perennial grain crop for human consumption. Selection targets for this crop are numerous, and breeding may be made more efficient by improving knowledge of the underlying genetic control for traits of interest. Nested association mapping (NAM) has proven useful in dissecting the genetic control of important agronomic traits in a wide range of crop species. This work introduces an intermediate wheatgrass NAM developed by crossing ten phenotypically divergent donor parents to a low-shattering common parent in a reciprocal manner, yielding 1,168 F1 progeny from 10 families. Using genotyping by sequencing, we identified 8,003 SNP markers and developed a population-specific consensus genetic map with 3,144 markers across 21 linkage groups. Using both genome wide association mapping (GWAS) and linkage mapping both combined across and within families, we characterize the genetic control of flowering time measured in two different ways across two locations and two years. We detected 35 QTL in GWAS and 20 in linkage mapping, demonstrating the complex genetic control of flowering time that is variable across years and locations as well as within families. The IWG NAM population was effective at detecting previously identified QTL, as well as a new QTL that aligns closely to the well-characterized flowering time orthogene from barley, Ppd-H1. Results demonstrated the utility of the NAM for understanding of the genetic control of flowering time and should be applied to additional traits of interest in IWG. Chapter 3 Perennial grain crops have the potential to improve agricultural sustainability, but few existing species produce sufficient grain yield to make this an economically viable option. The perennial forage species intermediate wheatgrass (Thinopyrum intermedium; IWG) has shown promise in undergoing direct domestication as a perennial grain crop using phenotypic and genomic selection. However, decades of selection at the current pace will be required to achieve yields on par with annual small grain crops. Marker aided selection could accelerate progress if important genomic regions associated with domestication were identified. Here we utilize the IWG Nested Association Mapping (NAM) population, with 1,168 F1 progeny across ten families to dissect the genetic control of brittle rachis, floret shattering, free-threshing ability, tillering, floret site utilization, plant height, and thousand grain weight. We used genome wide association analysis (GWAS) with 8,003 SNP markers and linkage mapping using within-family and combined analyses using a custom genetic map, with a robust phenotypic dataset collected from four unique year by location combinations. A total of 32 QTL in GWAS and 18 in linkage mapping were detected in at least two environments, and most large effect QTL were in common across the two analysis methods. We reveal that the genetic control of domestication traits in IWG is complex, with significant QTL across multiple chromosomes, sometimes within and across homoeologous groups and effects that vary across families. However, in many cases these QTL align closely with putative orthogenes for known domestication traits in related species and may serve as precise targets of selection and directions for further study to advance the domestication of IWG.
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    Storage Stability of Intermediate Wheatgrass (Thinopyrum Intermedium) Flour as Impacted by Agronomic Practices, Breeding, and Commercial Germination and Extrusion Techniques
    (2023-10) Loehr, Leslie
    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.
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    Structural Characterization and Glycemic Attributes of Intermediate Wheatgrass (Thinopyrum intermedium) Flour and Extracted Starch
    (2019-05) Zhong, Yingxin
    Intermediate wheatgrass (IWG) is an environmentally sustainable perennial crop with potential food applications. This study investigated the starch hydrolysis kinetics of IWG grown in Roseau (IWG-RS) and Rosemount (IWG-RM), Minnesota, USA and the molecular structure of their residual (resistant) starch after 2 hr hydrolysis. Hard red wheat (HRW) and Jasmine rice (JR) were compared to the IWG samples. Molecular size distribution and unit chain profiles of the RS fraction of raw starches after enzymatic hydrolysis were determined with gel permeation chromatography and high-performance anion-exchange chromatography respectively. Moreover, thermal properties, size distribution, granule size and morphology, as well as the unit and internal chain profile of extracted starches were evaluated. IWG flour had significantly lower total starch, lower RDS and higher lipid and protein contents compared to JR and HRW. JR flour had the highest eGI (49.2), with IWG-RM recording the lowest (40.6). Significant differences were observed in the glucan chain lengths of the RS fraction. JR had the shortest average chain length (DP=4.75) compared to HRW (DP=7.46), IWG-RS (DP=5.72) and IWG-RM (DP=4.85). IWG flour had slower starch hydrolysis kinetics compared to JR and HRW flour. The RS fraction of the samples consisted mostly of short chains. The glucan chain length of IWG RS fraction was also significantly affected by location. The amylose contents of IWG-RS and IWG-RM were 30.7% and 30.4%, respectively. IWG starches had the lowest gelatinization temperatures. Enthalpy of gelatinization (ΔH) of HRW was similar to that of IWG-RM. The λmax of the starches suggests that the amylose chains and internal chains of the IWG starches were longer than those of HRW and JR. IWG-RM has the least beta-limit dextrin and longer external chain. Unit and internal chain profiles of amylopectins between IWGs were similar. This study revealed that IWG could potentially be exploited for the preparation of foods with lower glycemic responses. IWG starches properties were similar to those of wheat. Differences in some starch properties were also observed between the IWG grown at different locations. Understanding the microstructure of starch from Intermediate wheatgrass can potentially optimize its chemical functionality.