Mountain Scholar :: Browsing by Author "Weir, Tiffany, advisor"

Browsing by Author "Weir, Tiffany, advisor"

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Open Access
Edible mealworms: can fermentation improve consumer acceptability and nutritional value?
(Colorado State University. Libraries, 2023) Wilson, John W., author; Weir, Tiffany, advisor; Bunning, Marisa, committee member; Stull, Valerie, committee member; Nair, Mahesh, committee member
As the global population increases, the demand for animal-based protein is also on the rise. To meet this demand, it is important to identify sustainable sources of animal protein that have a smaller environmental impact than conventional animal protein production. One potential solution to this challenge is the development of consumer-acceptable insect-based protein products utilizing the larva and pupae of Tenebrio molitor, a type of darkling beetle whose larval and pupal states are edible. These beetles can be reared in small spaces, do not require direct sources of fresh water, and convert feed into protein more efficiently than conventional meat production. In addition, their waste (frass) is dry, making it easier to contain than waste from conventional animal rearing operations, reducing the risk of contaminating the surrounding environment. In addition, the larvae and pupae can be eaten in their entirety, eliminating potential waste streams of byproducts associated with conventional meat processing. With less space, less water usage, more efficient feed conversion ratios, and nearly zero waste, the development of an edible mealworm industry in the global West would help relieve some of the pressures on the current animal protein systems and improve global food security. To accomplish this, it is necessary to generate a consistent demand in the global West for insect protein. Currently, in the United States, edible insects are largely relegated to ground powders designed to "hide" the insects or are placed in novelty products like chocolates and lollipops to confront people's notion of disgust. To introduce mealworm protein into the mainstream, it must be in a form that is accessible to the average American consumer, be safe to eat, and have comparable nutritional attributes as other protein-based products on the market. Tempeh fermentation techniques may be an appropriate approach to accomplish these goals. Tempeh fermentation uses Rhizopus oligosporus mycelium to knit together legumes into a solid cohesive substrate. The product can then be utilized in a variety of ways that are familiar to American consumers including stir frys, burgers, nuggets, and crumbles. This project seeks to utilize tempeh fermentation techniques to develop an insect-based product that is both consumer-friendly but also capitalizes on the known and emerging nutritional and environmental benefits of edible insects. In Chapter 1, I examine the safety of tempeh produced with various life stages of the Tenebrio molitor beetle. Samples were assessed for water activity (aw), and pH to determine the shelf stability of the products. Pathogenic risk was assessed through testing for coliforms, Salmonella and Listeria, and samples were analyzed for heavy meatal content via utilized Inductively Coupled Plasma and Mass Spectrometry (ICP-MS). This exploration allows us to determine best storing and cooking methods and helps identify critical control points in production to help minimize the risk to the consumer. In this chapter, I was able to demonstrate that tempeh made with Tenebrio molitor was just as safe as conventional soy-based tempeh and requires similar storage and cooking precautions to minimize the risks of consumption. In Chapter 2 we conducted a nutritional analysis of the insect-based tempeh products in comparison to traditional soy-based tempeh. We utilized ICP-MS to quantify the presence of micronutrients within each example. Samples were also analyzed for vitamins, macronutrients, and amino acid profile. We then calculated the protein digestibility using the Protein Digestibility-Corrected Amino Acid Score (PDCAAS). Comparison of results with traditional soy-tempeh products helps us to determine if the products provide comparable nutrition to products already on the market. It also helps to determine if the novel products will fill the nutritional space of more conventional sources of protein. This chapter found that the tempeh products made with the Tenebrio molitor had nutritional attributes comparable to conventional soy tempeh. Chapter 3 examines the bioavailability of iron within the sample set and compare the results to conventional bee samples, current on-the-market plant-based meat alternatives, and traditional soy-based tempeh. ICP-MS was utilized to quantify the amounts of iron present in each chemically digested sample. Then, digestates were added to Caco-2 human colonic cells to allow absorption of available iron. Iron absorption rates were then determined by using a human ferritin Eliza kit. This assessment helps us determine if the presence of insect protein improves the bioavailability of iron in a traditionally plant-based food and allows us to compare the availability of the iron in the novel products to conventional beef and current plant-based meat products. The bioavailability of iron in the novel products exceeded that of the conventional beef and the plant-based meat alternative. In Chapter 4, we conducted a consumer acceptability study to analyze the potential for consumer acceptance of a tempeh product made with 50% mealworms and 50% soybeans when compared to a commercial soy-based tempeh. An online survey was conducted to assess the public's attitudes to entomophagy, their current level of exposure to the practice, and the willingness to consume insects. Next, the mealworm soybean tempeh was evaluated by a trained sensory panel to develop a lexicon that describes the organoleptic attributes of the product. Finally, a blind in-person sensory evaluation was conducted to assess the overall acceptability of the product. During the in-person evaluation, participants were provided with different prompts to determine if details around the environmental impact of insect eating versus conventional meat production would affect the favorability of the product. Participants in this study rated the flavor equal to that of the commercial soy tempeh and majority of participants indicated they were equally or more likely to consume insect-based products again. The final chapter explores the need for research around branding and availability on insect-based food products to increase acceptance of entomophagy in Western society. This dissertation aims to determine the safety of utilizing edible insects in tempeh fermentation, examine the nutritional attributes of tempeh products made with various life stages of the Tenebrio molitor beetle, determine how effective these products are in filling their intended nutritional niches, and assess the potential for consumer acceptance of insect-based tempeh products. This dissertation provides a strong foundation for the understanding of the safety, nutrition, and acceptability of utilizing T. molitor-based tempeh as an alternative source of protein.
Open Access
Root microbial interactions to enhance wheat productivity under water stress
(Colorado State University. Libraries, 2018) Salem, Galal Saleh Ali, author; Weir, Tiffany, advisor; Stromberger, Mary, committee member; Wallner, Stephen, committee member; Vivanco, Jorge, committee member
Water stress is one of the obstacles that most profoundly affects plant growth and crop yields worldwide. Water stress causes serious plant growth problems such as suppression of cell growth and photosynthesis, disturbance of plant water relations, and increased production of the plant hormone ethylene, which reduces plant root and shoot length, consequently hampering the growth and productivity of crop plants. Wheat (Triticum aestivum L.) is one of the most important staple food crops, and is one of the most widely cultivated crops worldwide. Water deficit is the major limiting factor for wheat productivity, affecting yield and crop productivity. As a consequence, studying the water stress tolerance and productivity of wheat is extremely important to cope with the issue of food security in the face of a changing climate. Microbial inoculants that improve plant performance offer an environmentally friendly and sustainable strategy to cope with water deficit. Plant growth-promoting rhizobacteria (PGPR) are defined as a group of beneficial bacteria capable of colonizing the rhizosphere and contribute to increased plant growth and crop productivity via different direct and indirect mechanisms, such as production of plant growth regulators such as cytokinins, auxins, and gibberellins, inhibition of stress ethylene by ACC deaminase enzyme, or suppression of soil-borne pathogens by induction of plant defense mechanisms such as production of antibiotics or induced systemic resistance to cope with microbial pathogen attack. The purpose of this research was to assess the performance of 1-aminocyclopropane-1-carboxylate (ACC) deaminase- positive bacteria (ACC+ bacteria) inoculants isolated from Colorado soils on growth parameters and performance of different winter wheat genotypes grown in a greenhouse under water-stressed and well-watered conditions (Chapter 2). The results of this study showed that under water stress, leaf relative water content was improved among genotypes in response to inoculation, whereas the growth responses of winter wheat to inoculation with ACC+ bacteria depended on the wheat genotype tested. Understanding of the biological underpinnings of the relationships between different genotypes and PGPRs could be clarified by exploring the chemical signals that mediate these interactions. Therefore, in chapter 3, a global metabolomics analysis of rhizosphere-associated metabolites was conducted to identify chemical signals that may be important in these interactions. The prime objective of this chapter was to identify whether specific root metabolites were associated with improved resistance to water stress. Root exudates from three winter wheat genotypes, under well-watered or water-stressed conditions and with or without inoculation by ACC+ bacteria, were collected and analyzed for global metabolite profile differences. By using untargeted UPLC-MS/GC-MS models for studying root exudate profiles of winter wheat genotypes that differ in their ability to withstand water stress combined with multivariate statistical techniques (PCA and OPLS-DA), we were able to identify statistically and potentially significant biochemical compounds that may contribute to improvement the stress tolerance in specific winter wheat genotypes. The results revealed that metabolite profiles were most influenced by irrigation status, with global differences between water stressed and well-watered plants evident from both unsupervised (PCA) and supervised (OPLS-DA) ordination plots of the data. In particular, water stress plants had higher levels of the citric acid cycle intermediate, succinate, as well as organic acids such as lactic acid. These compounds have been shown to be produced by bacteria and to enhance plant growth under varying environmental stress conditions. The data also illustrate that metabolomic profiling is a powerful tool for generating specific hypotheses related to novel mechanisms of plant-microbe interactions for attenuation of water stress in winter wheat.
Open Access
Supplementing powdered high-fiber foods to alter gut microbial metabolism for colorectal cancer prevention
(Colorado State University. Libraries, 2016) Sheflin, Amy Marie, author; Weir, Tiffany, advisor; Broeckling, Corey, committee member; Melby, Chris, committee member; Pagliassotti, Michael, committee member
Trillions of microorganisms populate the human digestive tract and enhance immunity, improve digestion and inhibit pathogens when in healthy balance. However, a disruption of gut community balance is associated with a number of diseases including colorectal cancer (CRC). The purpose of this research was to investigate supplementation with two high-fiber foods, heat stabilized rice bran (SRB) and cooked navy bean powder (NBP), for potential to favorably alter the intestinal environment for CRC prevention. Study 1 aimed to assess differences in stool microbiota and associated metabolites in healthy individuals versus those diagnosed with CRC. Next, two pilot dietary interventions were undertaken (Study 2 and 3), one in healthy individuals and another in CRC survivors. Both pilot studies provided diets supplemented with SRB or NBP or macronutrient matched control foods and changes in stool microbiota and associated metabolites were assessed at baseline and after 2 and 4 weeks. The collective body of this research supports the hypothesis that gut microbiota and their metabolites differ with respect to CRC and that intervention with SRB or NBP can alter this profile. Despite similar increases in dietary fiber intake, SRB induced more significant change to gut microbiota and metabolites possibly due to differing chemical composition of plant fibers. Relative to NBP, SRB is rich in arabinoxylans, which structurally mimic the protective mucins lining the intestinal surface. Changes in both microbiota and metabolites observed with SRB supplementation are consistent with enrichment of glycan-foraging bacteria able to switch between dietary glycans (arabinoxylans in this case) and host glycans for energy. Acetate and propionate, potentially beneficial byproducts of microbial fermentation of glycans and other fiber components, increased at 2 weeks in CRC survivors. However, some of the observed changes did not persist at 4 weeks and further research is necessary to determine if more lasting changes are possible with these dietary interventions, as well as whether these altered microbial/metabolite profiles are associated with reduced risk of CRC incidence and recurrence.
Open Access
Using participatory action research methods to create nutrition education that sustainably improves diet diversity through women's empowerment
(Colorado State University. Libraries, 2021) Sly, Brittney Catherine, author; Weir, Tiffany, advisor; Melby, Chris, advisor; Cunningham-Sabo, Leslie, committee member; Leisz, Stephen, committee member
Malnutrition is a major cause of morbidity and mortality for vulnerable sub-Saharan African populations, and despite decades-long efforts from global and regional organizations, the prevalence of malnutrition is not improving. Many programs fail to address the underlying causes of malnutrition within specific cultural and community contexts, particularly issues that contribute to malnutrition such as hygiene, agriculture, education, and poverty reduction. Therefore, there is a need for more sustainable, culturally inclusive, and targeted malnutrition remediation interventions that address the multifaceted issues involved with the rising numbers of malnourished people in sub-Saharan Africa. The purpose of this research was to develop a nutrition-sensitive agriculture intervention, aimed at sustainably increasing diet diversity and food security at the household level, in a rural Rwandan community, using Participatory Action Research (PAR) methods to empower women as peer educators. Small groups of women (n=42), divided into 6 groups of 7, collectively received agriculture trainings and nutrition education over the course of 16 weeks, along with the tools and support to start and maintain kitchen gardens. A large group session, using PAR methodology, was conducted to guide self-reflection and knowledge-assessment, while empowering women educators to spread information throughout their community. By coupling the intention of nutrition-sensitive agriculture with the empowering and inclusive methods of PAR, the goal was to provide the framework for establishing more sustainable nutrition-sensitive agriculture interventions, while encouraging the dissemination of information to the larger community. Collaborative community-based nutrition-sensitive agricultural interventions in rural, poor Rwandan populations can increase household diet diversity to encourage sustained change in dietary patterns for nutritional adequacy. Using kitchen gardens as the conduit for change, households can increase their consumption of home-grown vegetables, as well as other nutrient-dense foods. Additionally, employing PAR methods within the intervention design to enable participants to serve as active contributors and peer educators, enhanced women's empowerment and contributed to increased agency, as well as widespread information dissemination. However, more research concerning the systems that affect food availability and agricultural markets is needed to enact changes in food security, as well as more investigation into the ways in which empowerment influences the spread of information throughout a community.
Open Access
Visceral adiposity and pro-inflammation: contributions and consequences of immunity
(Colorado State University. Libraries, 2017) Magnuson, Aaron Mark, author; Foster, Michelle T., advisor; Weir, Tiffany, advisor; Colgan, Sean, committee member; Dow, Steve, committee member
Obesity among Americans has reached a strikingly prevalent rate with ~36% of adults falling into this category. As this rate continues to rise, so do the number of individuals with chronic diseases associated with excessive adipose tissue accumulation. Dysregulation of adipose tissue is a fundamental driver of obesity associated comorbidities. In particular, deposition of adipose tissue within the visceral cavity is especially deleterious, while subcutaneous adipose tissue has been identified as being metabolically protective. Consequently, visceral adiposity is demonstrated to be more highly associated with increased pro-inflammation. This inflammation has been demonstrated to be the causal link between obesity and its associated comorbidities. The purpose of this research was to investigate why visceral adiposity is so detrimental. We propose that the lymphatic system is central to the heightened inflammatory potential associated with adipose tissue deposition in the visceral cavity. The visceral lymph node serves as the immune nexus between the visceral adipose tissue and the small intestines and is thus impacted by alterations in these tissues as a consequence of poor diet and obesity. In these studies we utilized mouse models of diet induced obesity (DIO) to elucidate the relationships between these tissues that potentially contribute to heightened pro-inflammatory potential of visceral adiposity relative to subcutaneous. We fed mice a high fat westernized diet (HFD) for 7 or 13 weeks, and then analyzed immune cell populations in the visceral and subcutaneous lymph iii nodes and adipose tissue and the small intestine, adipose tissue inflammatory markers, and lymph node morphology. Visceral adipose tissue had an inherently greater potential for pro-inflammation based on immune cell populations in lean controls relative to subcutaneous adipose tissue. Seven weeks of DIO was associated with decreased potential for immune suppression in the visceral adipose tissue, small intestines and visceral lymph nodes and elevated pro-inflammatory immune cell subsets. Consistent with this, pro-inflammatory cytokines were significantly elevated in the visceral adipose tissue. In association with this, visceral lymph nodes demonstrated hypertrophy, increases in total viable immune cells and immune cell subsets indicative of an adaptive like immune response. These changes were specific to the visceral cavity. Thirteen weeks of DIO caused a suppression of total viable immune cells and pro-inflammatory subsets in both the visceral adipose tissue and lymph nodes. Subcutaneous tissues were relatively unaffected. Alterations in immune cells were associated with significant fibrosis specific to the visceral lymph nodes. Increased incidence of comorbidities and immune related pathologies associated with visceral adiposity is likely, at least in part, a consequence of heightened pro-inflammation in the visceral lymph node as a result of chronic immune stimulation from both the visceral adipose tissue and small intestines. We propose that lymph node fibrosis is a result of chronic inflammation associated with obesity. In turn, this contributes to immune suppression that is associated increased susceptibility to pathogen infection and disease morbidity.

Browsing by Author "Weir, Tiffany, advisor"

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