Dissertations / Theses on the topic 'Veterinary and food sciences not elsewhere classified'

Understanding the effect of food insecurity of vulnerable individuals is necessary to develop strategies for improving lives of those individuals. In this study I explore the effect of a low-cost, unobtrusive intervention on food pantry clients’ choice of healthier food items at a local food pantry. A cross-sectional study was conducted at a food pantry in the Midwest U.S. using the randomized controlled trial method. Participants in the intervention group received a nutrition ranking information about the food items in the pantry during their visit. Both the intervention and control groups reported their food selections. Additionally, client demographic information was collected in surveys. Data were collected from October 2018 to January 2019. A total of 615 adults were recruited and randomized for the nutrition ranking intervention (n=300) and control group (n=315). Multiple linear regression models were used to predict the outcomes of the intervention while controlling for demographic characteristics such as age, gender, household size, and education level. There was no significant response to the nutritional ranking intervention as it appears that the intervention was ineffective at changing behavior. Results suggest that future studies are needed to determine a low-cost intervention for food pantry clients during their short time at the food pantry.

Poisoning of cattle by plants of the Pimelea species incurs heavy losses to individual producers in regions of South West Queensland, North Western New South Wales, South Australia, and the Northern Territory. Due to the vast

areas of affected land, control of the plant is perceived as non -viable. Therefore, the aim of this study has been to contribute to the development of methods to reduce the losses caused by the condition from an animal health

perspective.

Immunisation with conjugates of a purified mixture of Pimelea toxins and ovalbumin with varying inclusion ratios has resulted in the production of bovine serum IgG antibodies, which attenuate the effect of purified Pimelea

toxins on bovine pulmonary venule preparations in vitro. Cattle immunised with a vaccine batched from two conjugates from experimental studies have been shown to develop toxin specific antibody responses while affected and unaffected by poisoning at the time of immunisation. Experiments to evaluate the protective attributes of the vaccine under field conditions have produced consistent, yet non -significant results regarding liveweight and condition

scores of vaccinated animals. Therefore, no immediate conclusions can be drawn regarding the protective properties of the experimental vaccine without futrther investigation.

Investigation of a structure -activity relationship of the Pimelea toxins has resulted in new knowledge regarding key functional requirements for binding to and activation of protein kinase C (PKC). A structural variant of simplexin

was found not to activate PKC in vitro, therefore the conversion of simplexin to this compound in the rumen of cattle would provide a means of reducing the impact caused by Pimelea poisoning. It was found that hydroxyl groups at the 4- and 5- positions of simplexin were essential for PKC binding. Carbonyl functionality at position 3- of simplexin, although significant for PKC binding, was shown to be more related to the activation properties of the resulting complex. The alteration of hydroxyl functionality at the 20- position of

mezerein (a selected reference compound) was shown not to significantly alter binding, however no conclusion can be drawn regarding the importance of this functionality of simplexin.

Derivatisation of Pimelea toxin for assay by gas chromatography (GC) and high performance liquid chromatography (HPLC) was found not to be feasible.

Women who operate small-scale farms and sell to small markets in Indiana may encounter certain obstacles and constraints due to self-employment in the traditionally male-dominated field of agriculture. Researchers have recognized the role of sustainable agriculture ideology in attracting women to these niche agricultural markets. Despite increasing opportunities for women in sustainable agriculture, research suggests that traditional gender roles are often maintained, manifesting itself through several obstacles (Pilgeram & Amos, 2015). Female agricultural entrepreneurs encounter obstacles including work-family balance, geographic barriers, access to physical resources, access to financial resources, access to places of information. Previous research indicates that female entrepreneurs have less access to human, social, and financial capital to support their business ventures (Powell & Eddleston, 2013). However, this study explored the feminine perspective and management styles which may serve as beneficial resources.

The purpose of this study was to explore and describe existing obstacles encountered by female entrepreneurs in niche agricultural markets and their methods of building resilience in their business. Quantitative data was collected through an online survey of 62 agricultural entrepreneurs across the state of Indiana. Participants were asked questions pertaining to their business structure, resources, constraints, processes, achievements, and demographics. Several responses to open-ended questions were also collected and analyzed through open, axial coding. Study results include the diversity of the population, value of human capital resources, prioritization of quality products, significance of internal constraints, discrepancies in division of labor and women’s obstacles to access to social networks. A greater understanding of the obstacles encountered by women agricultural entrepreneurs can also provide valuable insight to Land-Grant University Extension, policymakers, and stakeholders in the Indiana agriculture industry.

STEM education is a top priority in the educational development of youth across the United States as the country tries to address the need of having a more well equipped, prepared, and educated workforce. Agriculture, food, and natural resources (AFNR) has the ability to provide a relevant context for engaging students in STEM education through experiential learning. Tragically, both STEM and AFNR struggle to reach and engage more diversified audiences, especially students of color. AFNR education provides an authentic avenue to center STEM engagement around addressing societal grand challenges like food and nutritional security, childhood-obesity, and climate change; issues faced by all communities. The approaches and steps taken to address these AFNR related grand challenges can all be explored through the lens of food systems. Food systems is a concept within AFNR that encompasses the interdisciplinary components of AFNR, STEM, and social sciences that provides a breakdown for the process and system involved in getting food from farm to fork. In an era where youth are more disconnected from understanding where their food comes from, food systems education has the ability to reconnect youth to the root of this issue and the potential to lead them to explore finding solutions to the grand challenges facing their generation. Furthermore, food systems education provides a context to engage youth in authentic learning experiences in nonformal and formal classroom settings around relevant issues with the potential to enhance their interests and concerns around these topics.

The purpose of this study was to explore and describe elementary school students’ interests and concerns about the food system, and their overall engagement in the learning experience after participating in an authentic learning based Virtual Agri+STEM Camp focused on food systems education, AFNR, and STEM activities. The convenience sample for this study was made up of elementary school students between grades 3^rd and 8^th grade (N = 99) who were either in the classroom or participating in an at-home Agri+STEM session. The majority of these students were from rural communities and most of them were African Americans. Quantitative data was collected before and after participation in the Virtual Agri+STEM Camp experience that using the research developed Food System Interest and Food System Concern instrument. Previous AFNR related experiences were also reported by students. The researcher also used an adapted version of the Intrinsic Motivation Inventory (IMI) and STEM Semantics survey to measure student engagement and attitudes after participating in the experience. Descriptive statistics were used to analyze the data, which included means, standard deviations, frequencies, and percentages. To explore the relationships between each of the variables, correlations were also computed.

There were four conclusions for this study. First, students that participated in the Virtual Agri+STEM Camp were motivated and engaged in the learning process while doing the Agri+STEM Camp activities. Second, students that participated in the Virtual Agri+STEM Camp were interested and concerned about the food system before and after participating in the Virtual Agri+STEM Camp. Third, African American student participants reported less previous AFNR experiences, yet they reported more interests and concerns in the food system than Caucasian American participants before and after completing the Virtual Agri+STEM Camp. Lastly, Students that felt more competent, saw the value, and were interested/enjoyed the Agri+STEM experience were more likely to be interested and concerned about the food system. Recommendations for future research and implications for practice and policy were discussed.

The farming of insects has been shown to require less land, feed, and water compared to traditional livestock maintenance, while proven to be a source of high-quality protein. The aversion of the Western culture towards edible insects is the major hurdle into their incorporation in the market, unveiling the challenge of integrating them into an existing familiar product. However, studies have shown that merely pulverizing insects into edible “flours” possesses difficulties on itself such as low solubility; severely altering the structural and sensory characteristics of food products upon their addition. Alternatively, scientists have turned to chemical protein isolation techniques to create insect flours with improved functionality. Furthermore, enzymatic proteolysis has shown to aid in extracting the protein bound to insoluble chitin and enhancing techno-functional properties. While this promising technique may open a range of possibilities, no research has been done regarding the incorporation of insect hydrolysates into a food matrix. The purpose of this work was to explore the production of insect hydrolysates with improved techno-functional properties and their impact in the physicochemical, structural, and sensory characteristics on a chosen model matrix: corn tortillas. Crickets (Acheta domesticus) were chosen due to their current relevance in the Western market.

Hydrolysates were produced with low (5%), medium (8%), and high (15%) degrees of hydrolysis (DH) either with Alcalase (AL) or Flavourzyme (FL). Alcalase cricket protein hydrolysates (CPH) resulted in higher fat content, which was suspected of possessing surface-activity. Overall, AL peptides displayed significantly (p < 0.05) higher emulsion and foam capacity and stability, suggesting stronger amphiphilic activity. On the other hand, FL peptides were more soluble and had a lower mean molecular weight, demonstrated by their lower glass transition temperatures. Both of these developments may be explained by Alcalase endopeptidase activity and Flavourzyme primarily exopeptidase activity. Treatments resulted in AL-peptides with large and medium size molecular weights that included hydrophobic terminal ends, while FL peptides were smaller and likely contained free amino acids. The difference in molecular weights were seen upon their addition in the raw corn masa, where AL-CPH increased elastic and viscous behavior compared to control, whereas the smaller FL-CPH lowered them due to the plasticizing capability of hydrophilic small peptides. The ability of FL-CPH to interact with corn macromolecules was observed upon thermal treatment, resulting in FL-tortillas with superior strength and extensibility compared to AL-tortillas. In fact, AL-tortillas fragility was seen by the rollability test, showing a complete disintegration of the tortilla structure. Raman spectroscopy further showed the heat-induced intermolecular interactions of FL-peptides with the corn macromolecules. Raman bands at 1049 cm^-1 in FL-tortillas allude to protein-starch complexes and the gauche-gauche region confirmed the presence of disulfide bridges in FL-tortillas, both of these developments were absent in AL-tortillas. Lastly, the formulation of corn chips with these CPH proved to be globally accepted by a population with diverse neophobia levels, confirming theories that consumers are willing to eat insects in an “invisible” format. Flavor and aroma profiles of the chips, quantified by a descriptive analysis study, revealed no commonalities between the two sets of chips. AL-chips were characterized as having corn, shrimp, and roasted peanut notes, while FL-chips were characterized as having tomato, ketchup, and French fry notes. Overall, enzymatic proteolysis was shown to generate cricket peptides with different characteristics, both able to be utilize as a functional ingredient for palatable food products.

High-school-aged youths have limited food safety knowledge and lack safe food-handling skills. However, these youths will prepare food for themselves and are frequently employed in the food service industry, where their food-handling practices can directly impact public health. Youths’ beliefs about safe food-handling behaviors are affected by Key Influencers in their lives such as peers, classroom instructors, parents, and celebrities including popular web-content authors or video hosts. Societal changes have prompted the elimination of Family and Consumer Science courses from many schools and the reduction of food-handler role models at home, while increasing access to unregulated sources of food-handling information such as information published on web-based platforms. These societal changes largely remove peers, classroom instructors, and parents from influencing youths’ food-handling behaviors.

The purpose of this study was to (1) evaluate the effectiveness of a researcher-developed food safety educational intervention at changing students’ food-handling behaviors specifically focusing on the role of subjective norms in generating behavior change and (2) conduct an exploratory content analysis of food safety messages delivered by blog authors and video hosts of popular web-content.

The researcher-developed curriculum was evaluated for adherence to academic standards and overall usability in the classroom using the Delphi Technique by a panel of secondary educators who were considered experts in the education field. The curriculum was evaluated for effectiveness at changing high school students’ food-handling behaviors through self-reported surveys and observation using GoPro head mounted and stationary cameras. Finally, content analysis was performed on food safety messages disseminated by authors and video hosts of popular blogs and YouTube videos, respectively.

Findings presented in this dissertation show that polyunsaturated fatty acids of soybean oil effectively reacted with high voltage atmospheric cold plasma gas species of various gases including hydrogen, nitrogen, and oxygen at room temperature without a catalyst. Hydrogenation, nitration, and epoxidation reactions were observed along with polymerization. Unexpectedly, hydrogen gas was not the primary source of atomic hydrogen observed under these experimental conditions. Rather, it is suggested that water vapor, present as an impurity, supplied hydrogen ions to the hydrogenation reactions. Nitrogen gas modified atmosphere is an electron-rich medium that catalyze reactions. Further investigation is suggested for optimizing the process of oil hydrogenation, as well as for exploring the potential to produce bio-based gels, lubricants, and greases.

Despite previously accepted dogma, several recently published studies in humans and mice have shown that mature red blood cells (RBCs) contain a pool of microRNAs. Their role is currently uncertain; however, it has been suggested that microRNAs may play a role in cellular communications as they can be transferred from the RBC to endothelial cells or other cells. This thesis investigated the set of differentially abundant microRNAs found in mature RBCs of felines with oxidative stress, using diabetes mellitus as an oxidant stressor. We postulated that individual microRNAs identified in this study, might be valuable targets for future studies, investigating the role specific microRNAs play in the development or progression of diabetes and in the oxidative damage inflicted on the red cell and other cells by this disease.

The first specific objective of this thesis was to document oxidative stress in diabetic cats. In the absence of validated assays to document the presence of oxidative protein damage in felines, we first evaluated the performance of a commonly used colorimetric assay for measurement of protein carbonyls (PC) in serum and plasma. Although within run variation was acceptable and performed well over a wide range of PC content values, there were severe limitations related to excessive between run-variation, hemoglobin interference, and difficulty of assay performance. Therefore, we developed and validated a new method, using a fluorescent probe. This new assay had good within and between-run variations, a broad analytical range, and was easy and rapid to run. Hemoglobin and triglyceride only affected the results when present at moderate to higher levels. To further evaluate their redox status, free-radical production and oxidative stress were measured in diabetic and healthy, control cats. The presence of oxidative stress was assessed by measurement of the resulting damage to biomolecules, and detection of antioxidant levels. Our data indicated the presence of protein and membrane lipid oxidation in diabetic individuals and suggest that the redox status of the mature RBC was shifted toward an oxidation state.

In the final chapter of this thesis, we document the presence of an abundant and diverse set of microRNAs in the mature erythrocytes of healthy and diabetic cats. While their function in the mature erythrocyte remains unknown, a difference was found in the microRNA expression patterns of diabetic and healthy cats. Our data uncovered severe bias in the microRNA sequencing such that the expression levels of some microRNAs appeared to be artificially increased and other diminished. The library construction kit used, appeared to be the cause of this bias. Among the 899 erythrocyte microRNAs sequenced, 12 differentially abundant microRNAs were identified in diabetic cats, however only 6 were differentially abundant by RT-qPCR. Let-7b, miR-1692, miR-339, miR-486 and a feline specific microRNA were increased in mature RBCs of diabetic cats, while miR-451 was decreased.

In conclusion, we have shown that diabetic cats have evidence of significant systemic protein and lipid oxidation as well as erythrocytic oxidative stress. The new, fluorescent PC content assay developed and validated herein could serve as useful tool to better understand the role and consequence of oxidative stress in feline diabetes or other diseases and to monitor antioxidant treatment. Further, this test could be readily adapted for use in other domestic species. Additionally, we have shown that a set of erythrocytic microRNAs are differently abundant in diabetic in comparison to healthy cats. The significance of such changes is currently uncertain. It could represent adaptation of erythroid precursors to changes in their environment during erythropoiesis and as such, these microRNAs may be useful biomarkers for altered hematopoiesis. If microRNAs play a role in communication between circulating mature RBCs and cells in their surroundings such as endothelial cells, the possibility that changes in their expression in this host cells may result in pathology is an intriguing possibility that need to be further explored.

It is well known that colonic microbiota is influenced by both intrinsic and extrinsic factors; out of all these, diet plays a major role. The traditional human diet has typically been high in overall dietary fiber intake, due its inherent presence in plant-derived foods. However, over the years, dietary patterns have transitioned into a low-fiber Westernized diet. This diet is increasingly implicated in colonic diseases. Dietary fiber consumption is known to increase microbial diversity, yet the mechanisms are still unclear. This is partially true because dietary fiber as a category is composed of a wide variety of structures, which may have divergent effects on the gut microbiome. The food industry has extracted, isolated, refined and purified non-digestible carbohydrates and, in some cases, modified them for improved function, which may influence their interaction with the gut microbiome. This study was developed in two phases: we first hypothesized that glucans produced by different processes were structurally distinct and that these fine structural differences in glucans would govern microbial responses to the polymers. To test this hypothesis, we first determined the structural characteristics of the glucans by gas chromatography and mass spectrometry, which revealed substantial structural differences among the glucans with respect to size and linkage patterns, consequently categorizing the glucans by structure (i.e., mixed linkage α-glucans, resistant maltodextrins, and polydextroses). The second study involved the in vitro fecal fermentation of these commercially available soluble glucans which are uniformly composed of glucose linked into different structural arrangements. We further hypothesized that each glucan would select for different microbiota and that there would be glucan-specific general responses across microbiomes. We were able to identify a variety of idiosyncratic metabolic patterns as well as differential organisms selecting for specific glucan structures. Although there were associations with glucan classes at the family level (e.g., Bacteriodaceae and Lachnospiraceae were discriminants of the resistant maltodextrins and polydextroses respectively), associations with glucans across individual species within these families varied. These findings suggest that microbiome responses to structurally distinct glucans depend upon both fine glucan structure and community context, and community metabolic phenotypes emerge from the interaction of the two. These findings are relevant to the food industry as they may enable optimization of synthesis to generate chemical structures that select for specific organisms and/or improve overall gut health.

Misunderstanding or misinterpreting specific animal behavior and welfare terminology, as well as principles of learning theory, may influence an individual’s perceptions of horse behavior. This error could potentially result in unnecessary applications of horse training principles and/or human interventions, which could potentially worsen the behavior or situation, leading to unnecessary welfare problems.

The purpose of this dissertation was to explore interpretations and understandings of specific animal behavior and welfare terminology, and learning theory principles, as applied to horses, among adults within the horse industry. Chapters 1 and 2 introduced, summarized, and linked the connection between horse behavior, horse welfare, learning theory, and schema theory. Chapter 3 and Chapter 4 each pilot-tested an online survey that was completed at the convenience of each participant to explore these interpretations and understandings. Chapter 3 (n = 46) utilized a survey containing general demographic questions, psychographic questions related to horse industry involvement, five videos of horse-human interactions (each with corresponding heart rate, HR, data), and 11 learning theory scenarios. Chapter 4 (n = 21) used a survey containing general demographic questions and five videos of various human-horse interactions, including the same five videos with horse HR information included. Using results from Chapter 3 and Chapter 4, further investigation of how individuals interpret and understand specific animal behavior and welfare terminology, and learning theory principles, as applied to horses was explored across a larger sample of adults within the horse industry. Chapter 5 (n = 1,145) utilized the same survey instrument as Chapter 3 among a more robust sample of adults within the horse industry.

Across all three studies, the main results suggest that although participants demonstrated a high level of agreement between each other when identifying fear, stress, and reactivity to describe a horse’s behavior, participants could not correctly define fear, stress, reactivity, or principles of learning theory, as related to horses. They also could not connect these states to an important physiological factor, i.e., HR, when identifying these states. Results across all three studies suggest that most participant demographics (such as age, gender, or race) did not influence participants’ abilities to correctly identify or define fear, stress, reactivity, or learning theory principles. Similarly, results from Chapters 3 and 5 suggest that most participant psychographics, such as horse ownership, or level of involvement with horses, did not affect ability to correctly identify key horse behaviors related to fear, stress, and reactivity, or understanding of learning theory principles, or ability to correctly define these states and principles.

Overall, this dissertation identified the need for additional education when it comes to clearly defining specific states such as fear, stress, and reactivity for individuals across the horse industry. Additional psychographic factors, such as an individual’s specific role or niche in the industry, or an individuals’ overall view of horses, should be further explored.

Three research studies were conducted to explore and explain the Colombian rural youth decision-making process regarding migration, university education and careers. The first study was a review of literature about Latin American rural youth. Forty-five peer-review articles that conducted in 13 Latin American countries, including Colombia, during the last 20 years were reviewed and analyzed. After conducting a systematic review, four main approaches of research were identified: (a) rural youth migration, (b) education and/or communication programs (e.g., rural extension), (c) rural youth expectations or futures perspectives, and (d) characterization of rural youth. Regarding methods, quantitative, qualitative, and mixed-method analyses were performed in these studies. Finally, main findings suggested that the rural context in these developing countries imposes socio-economic barriers for rural youth academic or professional development. Some authors also highlighted the importance of education or extension programs developed by local governments to empower Latin American rural youth.

The second study was a quantitative analysis that explored factors concerning the Colombian rural youth migration expectation using a multi-level approach (Level 1 = individual variables; Level 2 = family variables). Data came from 945 Colombian rural youth that responded to a national survey in 2016. Results showed that age, gender, and school grade were positively correlated to the migration expectation. Moreover, the family socioeconomic status was negatively correlated to the outcome. Family level variables explained 9% of the total migration expectation.

The third study explored and explained the Colombian rural youth perceptions about barriers they experienced during their career decision-making. This study used a convergent parallel mixed-method design. Participants of the quantitative phase were 155 Colombian youth that responded to a survey. On the other hand, the qualitative phase was made-up by five female and five male. These 10 people participated in an interview and wrote a short essay. All participants were members of the Colombian Rural Youth Network. Results showed that the career decision-making process for this Colombian occurred in a marginalized context, in which they did not have the same resources and/or tools to compete for university careers access with their urban peers.

As general conclusion of this dissertation, the Colombian rural context imposes restrictions for rural youth to pursue their career aspirations, which results in a push factor for youth to migrate to urban areas for career opportunities.

In this study, structural specificity of flavonoids was investigated toselectively inhibit starch digestive enzymes to stimulate the ileal-brake by triggering glucagon-like peptide-1 (GLP-1) through distal small intestine starch digestion which can regulate food intake and appetite. The double bond between C2 and C3 on flavonoid’s chemical structure plays a critical role to inhibit human pancreatic α-amylase, leading to π-staking interaction. Meanwhile, the hydroxyl group at C3 on the backbone benzopyran ring is intimately related to inhibition of the mucosal α-glucosidases. This selective inhibition is likely the result of fundamental differences in the protein structures of α-amylase and α-glucosidases, as they belong to different glycosyl hydrolase Families 13 and 31 (GH13 and GH31). α-Amylase has the catalytic active siteslocated in wide and shallow grooves on the protein structure, while α-glucosidases possess the narrow and deep catalytic pocket. In an acute study done on mice, luteolin, which had thehigher degree of selectivity toward α-amylase, showed a slow and sustained postprandial glycemic response with a reduced blood glucose peak and extended high glucose profile, compared to 3’,4’-dihydroxylflavonol as the selective α-glucosidases specific inhibitor. Quercetin was inhibitory of both α-amylase and α-glucosidases.Glycemic profiles in mice confirmed in vitro analysis of the inhibitory selectivity of the flavonoids tested. Additionally, the extended glycemic response with luteolin was accompaniedthe higher secretion of GLP-1 at extended postprandial times by delivering more starch portion into the distal small intestine where the ileal-brake and gut-brain axis activation takes place. Overall, selective inhibition of α-amylase by flavonoids potentially could be considered as a key approach to control glucose release from starch with slow and extended, but still complete, digestion for improved glycemic response and minimized adverse side effects that result from severely restricting or even shutting down starch digestion by pharmaceutical grade inhibitors.

When starch granules are gelatinized, many complex structural changes occur as a result of large quantity of water being absorbed. The enlargement of granule sizes and the leaching out water-soluble macromolecules contribute to the viscoelasticity. Starch pasting behavior greatly influences the texture of a variety of food products such as canned soup, sauces, baby foods, batter mixes etc. It is important to characterize the relationship between the structure, composition and architecture of the starch granules with its pasting behavior in order to arrive at a rational methodology to design modified starch of desirable digestion rate and texture. Five types of starch used in this study were waxy maize starch (WMS), normal maize starch (NMS), waxy rice starch (WRS), normal rice starch (NRS) and STMP cross linked normal maize starch. Evolution of volume fraction φ and pasting of 8% w/w starch suspension when heated at 60, 65, 70, 75, 80, 85 and 90 °C were characterized by particle size distribution and G’, G” in the frequency range of 0.01 to 10 Hz respectively. As expected, granule swelling was more pronounced at higher temperatures. At a fixed temperature, most of the swelling occurred within the first 5 min of heating. The pastes exhibited elastic behavior with G’ being much greater than G”. G’ increased with time for waxy maize and rice starch at all times. G’ and G’’ were found to correlated only to the temperature of pasting and not change much with the rate of heating. For WMS, WRS and STMP crosslinked NMS, G’ approached a limiting value for long heating times (30 min and above) especially at heating temperatures of 85°C and above. This behavior is believed to be due to the predominant effect of swelling at small times. For normal maize and rice starch, however, G’ reached a maximum and decreased at longer times for temperatures above 80 °C due to softening of granules as evidenced by peak force measurements. For each starch sample, the experimental data of G’ at different heating temperatures and times could be collapsed into a single curve. The limiting value of G’ at high volume fraction was related to granule size and granule interfacial energy using a foam rheology model. The interfacial free energy of granules were obtained from contact angle measurements and was employed to evaluate the limiting G’. The experimental data of G’ for all starches when subjected to different heating temperatures and times were normalized with respect to the limiting value at high volume fractions. The master curve for normalized G’ was employed to predict the evolution of G’ with time for different starches which was found to agree well with experimental data of storage modulus. A mechanistic model for starch swelling that is based on Flory Huggins polymer swelling theory was employed to predict the evolution of volume fraction of swollen granules. The model accounts for the structure and composition of different types of starches through starch-solvent interaction as quantified by static light scattering, gelatinization temperature and enthalpy of gelatinization, porosity and its variation with swelling and crosslinking of starch molecules within the granule from equilibrium swelling. Consequently, one could predict the evolution of texture of these starch suspension from the knowledge of their swelling behavior. Expressing the limiting storage modulus of complete swelling (volume fraction approaching unity) of starch suspension in terms of foam rheology, we were able to normalize the storage modulus of different types of starches with respect to its limiting value which is found to fall into a master curve. This master curve when employed along with the swelling model resulted in the successful prediction of development of texture for different types of starches. The above methodology can quantify the effects of structure and composition of starch on its pasting behavior and would therefore provide a rational guideline for modification and processing of starch-based material to obtain desirable texture and rheological properties.

Fruits play a necessary role in the human diet, and their cultivation is important to the prosperity of any country worldwide. However, fruit waste generated in large quantities in agricultural value chain is normally used to feed animals or directly disposed to landfill, ending up with low economic value and a heavy environmental burden. Agricultural waste that contains significant amounts of bioactive compounds can be utilized as byproducts and valorized through bioactives recovery. Conventional bioactive compounds extraction includes intensive uses of organic solvents and also has relatively low efficiency. Therefore, an environment-friendly alternative with higher extraction efficiency is needed. Cold plasma can convert gaseous medium to a highly reacting state with low energy cost, generating reactive species that are able to disrupt cell structures as well as modify material surfaces. This study has developed an innovative cold plasma-assisted extraction technology to enhance the recovery of bioactive compounds from fruit processing byproducts. The objectives of this study are to examine the effects of dielectric barrier discharge plasma on fruit pomaces, in terms of (i) surface microstructure and properties, (ii) extraction efficiency of their bioactive compounds, and (iii) bioactives composition and nutritional value of their extracts.

High voltage atmospheric cold plasmas (HVACP) generated with different working gases (air, argon, helium and nitrogen) were applied on tomato pomace (TP). In addition to creating ruptures on TP epidermal cells, HVACP treatments were found to decrease the water contact angles of tomato peels and accelerate the drying of tomato fruits, indicating the formation of more hydrophilic surfaces. Helium and nitrogen plasmas-treated TP showed increased PC extraction yields by 10%, and all HVACP-treated samples exhibited higher AA and changes in their phenolic compositions.

Grape pomace (GP) from red wine production was treated by helium-HVACP for different time periods (5, 10 and 15 min). Similar cell structure disruption and surface hydrophilicity enhancement were observed, and the effects became more significant as treatment extended. HVACP treatment also increased the total phenolic content in GP extracts, by 10.9−22.8%, which contained a higher anthocyanin concentration and showed an improved AA (16.7−34.7%). Furthermore, competitive effects of HVACP treatment on PC extractability enhancement and their degradation were observed.

The results of this study have proved that HVACP-assisted extraction successfully improved the extraction efficiency of bioactive compounds from fruit pomace and enhanced the nutritional quality of their extracts. This novel technology is a promising method for valorizing different agriculture byproducts into functional food ingredients and nutraceuticals with high nutritional values, which thus can bring significant economic benefits to the agricultural, food and nutraceutical industries.

Community gardens and youth-based programs in urban agriculture have potential to engage youth, especially minorities, in personal development, community building, and healthy eating promotion. This research study explored the role of urban agriculture at the Felege Hiywot Center (FHC), in promoting life skills, entrepreneurship, and healthy eating intentions among minority youth engaging in its programs. The study employed a mixed methods approach through surveys (n=24) and semi-structured interviews (n=10). The Theory of Planned Behavior (Ajzen, 1991; Fishbein, 2000) served as the conceptual framework with three predictive variables to life skills, entrepreneurship, and healthy eating intentions. Community partnerships, program structure, and individual background factors were measured, and relationships between life skills and entrepreneurship were explored. Results obtained from the analysis for both surveys and interviews indicate that participation in FHC promotes life skills, entrepreneurship, and healthy eating intentions for minority youth who engage in its programs. Overall, participants acknowledged the role of volunteers, professionals, sponsors, FHC structure, and individual background factors in promoting life skills, entrepreneurship, and healthy eating intentions. Qualitative data reports more in-depth descriptions of minority youth’s experiences at FHC’s youth program that impacted their daily lives and career decisions. Quantitative and qualitative results highlighted the leadership at the Felege Hiywot Center as particularly influential This research study contributes to the literature on the impacts of urban agriculture youth programs that incorporate experiential learning, farm-based education, and student centered-learning with youth development philosophies. The study also generated a conceptual framework that shows the interactions of different factors that lead to intentions. The results from this study support and extend prior research that suggests positive, lasting impacts from youth-based programs in urban agriculture.

The most common food and supplement prebiotic fiber is inulin – most commonly extracted from chicory root. Fructo-oligosaccharide (FOS) is a smaller version of inulin, both containing mainly fructose units with β-1,2 linkages. FOS/inulin has been used, and studied, as a prebiotic for decades. The potential of alternative prebiotics intrinsic in whole foods, such as in tubers, grains, vegetables, and pulses – the world’s most common staple crops – are not as commonly recognized as prebiotics, though have this potential if fermentable in the gut. If such alternative sources of prebiotic ingredients could be established it would allow for cheaper, possibly more effective, and more diverse food product development options beyond FOS/inulin.

This study demonstrates the potential of tubers, grains, and pulses as prebiotics in relation to their in vitro human fecal fermentation rate, short chain fatty acid (SCFA) production, and microbiota indicators of alpha diversity and impact on key bacterial genera. Fecal samples were obtained from three diverse healthy human donors and used as the initial bacterial inoculum to simulate conditions in the human gut (colon). Substrates (n=35), after undergoing an upper gastrointestinal tract simulated digestion, were fermented by each individual donors’ inoculum separately, and measurements after 6, 12, and 24 h of fermentation were made on gas production, SCFA metabolite production, and microbiome composition.

The results of this study establish high fermentability and potential prebiotic effects of dietary fibers from tubers, grains, and pulses. Whole foods, ground and cooked the same way, produced dietary fibers that were largely insoluble, but surprisingly fermentable with high SCFA levels, mostly slow fermentation profiles indicating high tolerability, and mostly promoting diverse microbiota responses compared to FOS. Generally, whole food fibers had higher fermentability than similar isolated fibers. Overall, the processing steps, such as atmospheric or pressure cooking, tested in some pulses did not detract, or add to, the prebiotic abilities of the substrates. Each food fiber substrate had unique effects on the gut microbiota parameters tested. Gut microbiome compositional responses to the same substrate varied significantly among the three donors, but notably SCFA metabolite responses were similar among donors.

This dissertation investigates two major structure-function relationships important to food science: vitamin stability and water-solid interactions. Thiamine, vitamin B₁, is an essential micronutrient in the human diet. While thiamine is found naturally and as a fortification supplement in many foods, it is chemically unstable on exposure to heat and some co-formulated ingredients, with degradation exacerbated in prolonged shelf-life products. The instability of thiamine is a concern for the development of dietary deficiencies, which are prevalent even in developed countries; however, thiamine stability is not widely studied in the food or pharmaceutical industries. Thiamine is commercially available in two salt forms: thiamine mononitrate (TMN) and thiamine chloride hydrochloride (TClHCl). This study focused on documenting the storage stability of thiamine in solution, considering the effects of which commercially available salt form of the vitamin was used, vitamin concentration, pH, and ions present in solution by monitoring chemical stability and degradation kinetics over a 6-month to 1-year period following storage at 25-80ºC, and expanded these studies into food systems (bread doughs). The results from these studies, including the reaction kinetics of thiamine degradation, the degradation pathway, and the sensory impacts of the degradation products formed, especially as affected by pH and food matrix, can be used to improve thiamine stability and delivery in foods.

The studies of water-solid interactions in this dissertation covered two topics: 1) the effects of formulating a variety of food-relevant additives on the crystallization tendency of amorphous sucrose; and 2) the effects of formulation on the moisture sorption behaviors and physical stability of spices, herbs, and seasoning blends. Sucrose lyophiles were co-formulated with a variety of additives and stored at 11-40% relative humidity (RH). The structural compatibility of sucrose with the additive, and related intermolecular interactions, dictated the tendency of the additive to either delay, prevent, or accelerate sucrose crystallization. Spices, herbs, and seasoning blends were exposed to increasing RH (23-75%) and temperature (20-50ºC) to determine the effect of storage and formulation on a variety of physical properties. In general, as complexity of blends increased, physical stability decreased. While this dissertation covers a wide variety of food chemistry and food materials science topics, including vitamin chemical stability, amorphous sucrose physical stability, and moisture sorption behaviors of spices, herbs, and seasoning blends, the findings provide valuable information on the chemical and physical stability of ingredient systems and how the structure-function relationships of the systems can be controlled for optimal ingredient functionality.

Silver carp (Hypophthalmichthys molitrix) are an underutilized, invasive fish threatening native species throughout major water systems in the United States. The goal of this research was to use silver carp meat to create a value-added product, to analyze the changes in physicochemical structure and consumer liking over time, and to evaluate the benefits of adding soy, pea, and a combination of soy and pea protein isolates to the formulations. Fish nuggets were prepared from minced meat in four treatments consisting of 3% soy protein isolate (SPI), 3% pea protein isolate (PPI), a combination of 1.5% SPI and 1.5% PPI, and a control without plant protein isolate. Nuggets from each treatment were stored frozen for 1.5, 8.5, and 13.5 weeks. Proximate composition, pH, cook loss, textural hardness, expressible moisture, color, microbial counts and lipid oxidation were evaluated. Sensory acceptability was also evaluated for each frozen storage time period and treatment. A descriptive (QDA^™) trained sensory panel was also conducted on all treatments independent of the storage testing. Results showed that lipid oxidation and textural hardness significantly (P < 0.05) increased with frozen storage time. PPI had significantly lower expressible moisture compared to the control at week 1.5, but there were no statistically significant differences between treatments at weeks 8.5 and 13.5. Similarly, formulations with PPI improved (p<0.05) cook loss for week 1.5, but not week 8.5 or 13.5. Overall, sensory acceptability did not change (P > 0.05), with the exception of decreased degree of liking scores for SPI aroma (p=0.03) and flavor (p=0.03)) during the frozen storage period; all degree of liking scores remained above 6.5 throughout analysis, indicating that consumers’ acceptability of the sample treatments over time despite the changes in physicochemical structure. The descriptive panel created an attribute lexicon for the aroma, flavor, and mouthfeel of the fish nuggets and did not find significant differences in intensities for those attributes between the treatments. Although there were measurable changes in oxidation, texture, expressible moisture, and cook loss over 13.5 weeks, these changes did not impact sensory acceptance. The addition of protein isolates improved water holding capacity initially but did not maintain those benefits over extended shelf life and had little impact on consumer liking during any time period. Overall, this study demonstrated that value-added products such as silver carp nuggets can be created using an otherwise under-utilized fish. The fish nuggets had high sensory acceptability, and the addition of protein isolates did not significantly improve their sensory characteristics; therefore, silver carp nuggets can be formulated without the need of additional protein additives .

Farmers in the digital age require accurate, relevant farm-level data to make sound management decisions for their operations. Mobile applications, or apps, are emerging as a valuable management and decision-making tool for farm operators, but are still in their infancy as a technological innovation. Farmer adoption and use of mobile apps has received relatively little attention in the scholarly literature compared to more established farm management tools and communication media. The researcher examined Indiana farmers’ use and perceptions of mobile apps as tools for management and decision-making. A theoretical perspective was developed from the Diffusion of Innovation Theory and the Technology Acceptance Model to guide the investigation. Data on attitudes, behaviors, and demographic characteristics were collected through interviews with 55 Indiana farmers in late 2018 and early 2019. Quantitative interview items were analyzed through descriptive statistics while open-ended items were coded for emergent themes.

Study participants reported a median age of 41 years and an average of 26 years farming. Nearly all study participants (98.2%) considered mobile applications useful to farm operations. A smaller but significant majority (76.4%) of participants rated mobile apps as easy to use. In terms of content, the most common use of apps among study participants was for general purpose utilities such as banking and messaging, followed by weather and agriculture-related apps such as Granular and FieldNet. Ease of use and content of application were among attributes considered most important by study participants when considering adoption of new apps. About three-fourths (76.4%) of the study participants indicated intentions to adopt additional mobile applications in the future.

A series of items addressed study participants’ awareness of open source technology. About three-fourths (72%) indicated not previously having heard of the terminology. When asked to share their thoughts on the term open source, a large majority (84%) of participants provided vague or seemingly unrelated responses ranging from cloud-related, to the capability of apps to exchange information, to software being open to all users.

As part of the analysis, the researcher categorized study participants into one of three adopter categories – early adopters, early majority, or late majority – based on the length of time participants reported using mobile apps, attitudes toward the technology, and intention to adopt apps in the future. Cross-tabulation analysis revealed that early adopters of mobile app technology did not differ significantly at the .05 level from later adopters in terms of age, years farming, or size of operation.

Finally, an empirical test was conducted to assess utility of the Technology Acceptance Model for conceptualizing behavioral intent to adopt mobile agricultural applications. As expected from theory, correlational analysis revealed positive and moderately strong relationships (p < .05) between perceived usefulness and attitude toward mobile applications, and between perceived ease of use and attitude toward mobile applications. The relationship between attitude and behavioral intention to adopt additional mobile applications was statistically non-significant at the .05 level, contrary to theory. The importance of exploring alternative theoretical perspectives in future research is discussed.

Results from this research contribute to the growing literature on how farmers assess and use mobile applications as farm management and decision-making tools. Findings have implications for application developers, as well as those involved in education and marketing of mobile agricultural applications.

Effective enrichments for farm animals are increasingly important to address public concerns about farm animal welfare and improve the welfare of the animals we raise. The public’s concern has increased in recent years as the management and care that farmers give their animals has become more apparent to them. Some of the conditions in which animals are kept are emotionally not appealing to the public. One such condition is farrowing crates for sows and piglets. The sows are confined in a small space with no social contact and cannot perform nesting behaviors. Farrowing crates are widely used though, as they allow farmers to handle piglets without fear of sow aggression, meet individual sow nutritional needs, and personalize care. Piglet mortality due to crushing is also decreased with crate use. Sow welfare in farrowing crates can be improved through environmental enrichments. Enrichments improve welfare by increasing species-specific behaviors, creating a more complex environment, reducing abnormal behaviors, and increasing an animal’s ability to cope with stressful situations. For pigs, different enrichments have been shown to decrease stereotypies, like sham chewing and bar biting, decrease harmful redirected behavior towards pen mates, like tail biting and belly nosing, increased exploratory behavior, and increase positive affect. Straw has been found to be the best enrichment for pigs because it allows them to perform motivational behaviors such as rooting, foraging, and nest building. It is also complex, manipulatable, destructible, and ingestible, which are important attributes of effective enrichments. Unfortunately, straw cannot be used in farms that have slurry systems, as the straw will fall through the slats into the pit below and cause drainage issues. This includes farrowing crates. There have been a few studies on alternative enrichments for sows in crates, like cloth tassels, but they are not as effective as straw and are rarely used on farm.

Most enrichments target pigs’ motivations to forage, root, graze, or build nests. Pigs perform other behaviors and may have other motivations that enrichments have not targeted yet. One such behavior is scratching. In a semi-natural environment, pigs will rub against trees and bushes. In confinement, pigs rub on fences, walls, and even allow people to scratch them with their hands. There have been no recorded studies done on scratching enrichment for pigs. Many studies have been done in the dairy industry exploring rotating brushes. These brushes have been implemented successfully on commercial farms and are used by cows to groom and scratch themselves. A similar device may allow pigs to also satisfy their itch. Our aim is to provide scratching enrichment to sows in farrowing crates. Since there have been no studies recorded on scratching enrichment or scratching in pigs in general, several steps had to take place before addressing the topic for sows in crates. The first project’s aim was to see what materials pigs prefer to scratch on and their willingness to use such an enrichment.

The first project consisted of 2 experiments. Exp. 1 was a pilot study where 5 different materials on scratch posts were presented to a pen of gestating sows. The scratch posts were constructed from polyvinyl chloride (PVC) pipes, boards, and a gate post. Five different materials were attached to the boards: white, soft, long-bristled brushes (White Brush), red, hard, short-bristled brush (Red Brush), black, short-bristled, astro-turf-like mat (Plastic Mat), colorful coir, hard, short-bristled mat (Fiber Mat), and blue, plastic, large-round-bristled combs (Plastic Combs). The 8 sows received all 5 scratch posts in their pen for a habituation day and then 7 d of testing. During testing, video was continuously recorded from which 2 behaviors were collected; scratching and interacting. Sows scratched the most on Plastic Mat followed by Fiber Mat, Plastic Combs, and Red Brush. The White Brush was scratched on the least. The top 3 preferences were chosen to proceed to Exp. 2.

Experiment 2 for sow preference was performed on several pens (N=14) of sows and gilts with Plastic Mat, Fiber Mat, and Plastic Combs to narrow the preference down to 2 materials to proceed to the farrowing crates. The experiment was carried out in repetitions. Each repetition tested 4 pens at a time. The scratch posts were modified from Exp. 1 and each material was placed in a pen. Due to material destruction only 2 repetitions were carried out, both ending a little early (N=8). During the first repetition (Rep 1), sows ate and destroyed all the Plastic Combs within 2 d. The Plastic Comb scratch posts were pulled from the study and the second repetition (Rep 2) only had the Plastic Mat and Fiber Mat represented. An observation was made that one of the pens in Rep1 had extra feed on their floor and were not destroying their materials as fast as the other pens. So for Rep 2, more modifications to the scratch posts were made and the sows were given a little extra feed. The scratch posts were still destroyed in Rep 2 proving that the sows’ hunger and motivation to perform oral manipulations overwhelmed scratching behaviors. However, from the data that was collected sows spent more time and more frequently interacted with the Fiber Mat compared to the Plastic Mat. They more frequently and spent more time interacting than scratching with the enrichments but scratched on both enrichments the same amount of time and frequency (Durations: F_1,112.6 = 13.63, P = 0.0003; Frequencies: F_1,111.9 = 19.72, P < 0.0001).

The plastic and fiber mats were presented to sows in farrowing crates for the second project by default. Sows (N=18) of parities 2 (P2) and 3 (P3) were housed for 25 d and assigned no enrichment (Control) or to a scratch pad treatment of plastic mats (Plastic) or fiber mats (Fiber). All were assessed for lesions, abnormal behaviors, eating and scratching behaviors, and time spent in different postures and behaviors. Scratching bouts occurred in short durations and were intermittent throughout the day. Parity 2 Plastic sows scratched for a longer total duration than P2 and P3 Fiber sows, P3 Plastic sows, and P2 Control sows (F_2,11 = 11.94, P = 0.002). Parity 2 Plastic sows also displayed scratching bouts more frequently than all except P3 Control sows (F_2,11 = 18.46, P = 0.0003). There were no body lesion differences between treatments (P > 0.05). Abnormal behaviors (P > 0.05) and proportion of time spent in different postures (F_2,94 = 0.0003, P = 0.999) did not differ among treatments.

The primary goal of this research was to summarize the occupational farm-related fatalities of Indiana farmers 55 years and older and to recommend evidence-based intervention strategies targeting older farmers who perform activities that involve the cutting and trimming of trees. The primary activities consisted of (1) preparing a summary of occupational farm-related fatalities of farmers who were 55 years and older, (2) preparing a summary of occupational farm-related fatalities of older farmers who were performing activities in a woodlot setting or that included the occasional cutting and trimming of trees, and finally (3) the development of recommendations for evidence-based injury prevention strategies targeting older farmers who conduct occasional woodcutting activities.

The summary of older Indiana farmer fatalities identified a total of 388 fatalities reported between 1988 and 2017 with an increase in the number of reported fatalities over the period of 2012-2017. Tractors were identified as the most common source of injury (40.5%) with tractor overturns involved in no fewer than 86 cases or 22.2% of all cases. Older farmer fatalities for occasional woodcutters accounted for 40 fatalities with the cutting and trimming of trees to be the most common cause of injury (67.5%).

Core desired safety competencies were identified that were used to develop injury prevention strategies based upon the summary of injuries, areas of concerns reported in the review of literature and the results gathered from the summaries of Indiana older farmers killed while performing woodcutting activities. A pilot evidence-based intervention instructional presentation was developed with the assistance of a panel of experts to be used by Extension Educators to increase awareness of the target population of current safety practices relating to woodlot activities.

Obesity and nutrition-related non-communicable diseases continue to be major challenges that are increasing in severity worldwide. Science-centered carbohydrate dietary strategies may be a viable approach to help address such challenges. Recent reports from our laboratory indicate that certain carbohydrates with slow digestion profiles have the ability to trigger the gut-brain axis and reduce food intake and to slow gastric emptying and potentially affect appetite. Slow carbohydrate digestion may have other impacts on energy metabolism that have not been explored. In the current investigations, we sought to better understand the delayed gastric emptying profile of pearl millet-based foods as well as to understand how altering carbohydrate digestion rate impacts substrate utilization for energy.

In the first study, the physical breakdown of pearl millet couscous particles in a simulated gastric environment (Human Gastric Simulator) was studied compared to wheat couscous matched in particle size, and select physicochemical properties of each type of couscous were characterized. Because we previously showed that pearl millet couscous had a marked delay in gastric emptying compared to white rice, boiled potatoes, and pasta in a human study in Mali, the objective of the first investigation was to test the hypothesis that pearl millet couscous was more resistant to breakdown in the stomach than wheat couscous and would take longer to empty. Our findings indicated that pearl millet couscous instead broke down into smaller, more numerous particles than wheat couscous. However, pearl millet had a slower starch hydrolysis property compared to wheat couscous per unit surface area. Pearl millet also had a smaller amylose chain length (839-963 DP) compared to wheat (1225-1563 DP), which may enable a denser packing of millet starch molecules that hinders hydrolysis. We also visually observed that the pearl millet particles formed a paste while breaking down that could reasonably generate viscosity in the stomach to potentially delay gastric emptying.

Based off the findings from simulated gastric digestion, we next conducted a human study (n=14) in the U.S. to test the hypothesis that pearl millet-based foods (couscous – commercial and self-made, thick porridge) would reduce glycemic response, increase satiety, and delay gastric emptying compared to wheat couscous and white rice. We complemented this human study with additional in vitro work using an advanced gastrointestinal digestion system (TIMagc) to determine if the viscosity of pearl millet couscous particles as they were breaking down in the stomach was contributing to a decrease in gastric emptying. Our findings indicated that all the pearl millet-based foods and wheat couscous had lower overall glycemic response than white rice, but only the self-made millet couscous showed higher satiety through subjective appetitive response ratings. Surprisingly, there were no differences in gastric emptying among the foods. Additionally, the half-emptying times for these foods were all ~3 h, which is similar to the comparably low half-emptying times observed for white rice, boiled potatoes, and pasta in the previous Mali study. We now hypothesize that there may be diet-induced changes in gut-brain axis signaling when slowly digestible carbohydrates are consumed repeatedly over time, perhaps through modulating the number or sensitivity of small intestinal L-cells. We also found that millet couscous did not exhibit high viscosity in the TIMagc, suggesting that viscosity was not impacting its rate of gastric emptying. We conclude that at least some pearl millet-based foods possess a slow digestion property that may act to trigger the gut-brain axis or ileal brake to increase feelings of satiety or slow gastric emptying, but the discrepancy between U.S. and Malian populations requires further study.

In the final investigation, we examined how altering carbohydrate digestion affected partitioning of carbohydrate versus fat for oxidation as well as the efficiency of switching oxidation between these two substrates (termed “metabolic flexibility”) in mice. Metabolic flexibility has been associated with good health related to decreased adipose tissue in the body and improved insulin sensitivity and may have implications on weight management. Carbohydrate digestion was adjusted by: (1) testing mice that lacked a complete set of enzymes by knocking out maltase-glucoamylase (Mgam; null) for moderating starch digestion versus testing wild-type mice; (2) using diets in these two groups of mice to moderate starch digestion that had different levels of resistant starch (53%, 35%, and 18%), had only raw corn starch or sucrose, or were high in fat; and (3) providing a supplement of fungal amyloglucosidase (AMG) to the mice treatment groups to increase starch digestion. Respiratory exchange ratio (RER) was measured through indirect calorimetry and mathematical modeling was used to characterize the diurnal shifts in RER (sine equation) as well as carbohydrate versus fat oxidation and metabolic flexibility (percent relative cumulative frequency [PRCF] with Weibull and Mixed Weibull Cumulative Distribution functions). Our results suggest that null mice lacking Mgam had somewhat increased metabolic flexibility than wild-type mice despite exhibiting minimal to no effects on carbohydrate oxidation. Intriguingly, the raw corn starch diet increased fat oxidation and generally promoted metabolic flexibility, although it did not increase carbohydrate oxidation relative to the other carbohydrate-predominant diets. Increasing carbohydrate digestion through AMG supplementation increased carbohydrate oxidation, and generally prompted earlier shifts to carbohydrate oxidation than without AMG supplementation. These findings provide a basis for better understanding the metabolic consequences of altering carbohydrate digestion and establish novel tools that can be utilized in future investigations. Overall, we propose that moderating carbohydrate digestion provides the ideal combination of balancing carbohydrate and fat oxidation while promoting metabolic flexibility.

In conclusion, a slow digestion property may enable some types of pearl millet to trigger the ileal brake and gut-brain axis feedback systems to decrease glycemic response and increase satiety. Moreover, consuming carbohydrates with slow digestion may optimize substrate utilization for energy by the body. In addition to triggering the ileal brake and gut-brain axis, modulating carbohydrate digestion to more effectively switch between carbohydrate and fat for oxidation may be beneficial for weight management and metabolic disease prevention.

Low calorie sweeteners (LCS) provide sweetness with little to no energy. Each sweetener has a unique chemical structure that possesses unique sensory and functional characteristics. While LCS are generally considered in aggregate, these unique chemical structures have potential implications for sensory, metabolic, and behavioral differences that may impact body weight and glycemia. Therefore, two, twelve-week experiments were conducted to determine the effect of chronic LCS consumption on body weight, glycemia, and ingestive behaviors.

The first experiment investigated the differential effects of four LCS (saccharin, aspartame, rebaudioside A, and sucralose) and sucrose consumed for twelve weeks on body weight, glycemia, and ingestive behaviors among healthy adults with overweight or obesity (body mass index (BMI) between 25 and 40 kg/m²). In a parallel-arm design, 154 participants were randomly assigned to consume 1.25 to 1.75L of beverage sweetened with 1 of the 5 sweeteners daily for 12 weeks. Body weight was measured every two weeks; energy intake, energy expenditure, and appetite were assessed every 4 weeks; and glucose tolerance was measured at baseline and week 12. Every four weeks, participants completed 24-hour urine collections to determine study compliance via PABA excretion. Sucrose and saccharin consumption led to increased body weight across the 12-week intervention (Δ weight = +1.85 and +1.18kg, p ≤ 0.02) and did not differ from each other. While there was no significant change in body weight with consumption of the other LCS treatments compared to baseline, changes in weight in comparison to the sucrose treatment (sucrose – LCS) were significantly different for aspartame, rebA, and sucralose after 12 weeks (weight difference = 1.13, 1.25, 2.63kg, respectively; p ≤ 0.03). In addition, change in body weight at week 12 was significantly lower between sucralose and all other LCS (weight difference ≥ - 1.37 kg, p=0.008).

The second experiment investigated the effect of daily aspartame ingestion on glycemia, body weight, and appetite. One hundred lean (BMI between 18 and 25 kg/m²) adults were randomly assigned to consume 0, 350, or 1050 mg aspartame/day for twelve weeks in a parallel-arm design. This experiment followed a similar protocol but measured body weight and blood pressure weekly and contained a 240-min glucose-tolerance test (OGTT) with measurements of selected hormones at baseline and week 12. Participants also collected 24-h urine samples every four weeks. There were no group differences for glucose, insulin, resting leptin, glucagon-like peptide 1, or gastric inhibitory peptide at baseline or week 12. There also were no effects of aspartame ingestion on appetite, body weight, or body composition.

These trials demonstrate that all LCS contribute negligible energy but should not be aggregated because of their differing effects on body weight. Sucrose and saccharin consumption significantly increased body weight compared to aspartame, rebA, and sucralose. This differential change in body weight among LCS indicates individual LCS likely exert different physiological responses beyond the contribution of sweetness with negligible energy. Saccharin, rebA, sucralose, and aspartame (ingested at three doses) for twelve weeks had no effect on glycemia. These data do not support the view that LCS are problematic for the management of glycemia. If substantiated through additional testing, findings from this trial have implications for consumers, food industry, clinicians, and policy makers. Some LCS may not hold the anticipated beneficial effects on body weight (e.g., saccharin) and positive effects of one LCS (sucralose) may be attenuated if combined with select other LCS. Going forward it will be important to consider each LCS as a distinct entity with respect to its potential health effects.

An increasing number of individuals with physical disabilities or mental disorders are incorporating specially trained service dogs as an assistance aid to improve functionality. In addition to the tasks that service dogs are rained for, studies also suggest that service dogs may benefit psychosocial health and wellbeing. However, current knowledge on these potential benefits is limited by methodological weaknesses without multi-method assessment. There remains a need for empirical and replicable quantification the psychosocial outcomes of service dog assistance and companionship.

The objective of Chapters 1-3 was to summarize, evaluate, and quantify the effects of service dogs on psychosocial health among individuals with physical disabilities. Chapter 1 conducted a systematic literature review of N=24 articles describing the effects of guide, hearing, mobility, and medical service dogs on standardized measures of psychosocial functioning. Chapters 2 and 3 conducted an empirical investigation using quantitative and qualitative methods to quantify the psychosocial effects of mobility and medical service dogs among N=154 individuals with physical disabilities. Results identified specific psychological, social, and emotional benefits that are associated with having an assistance dog or service dog among diverse populations with physical disabilities or chronic conditions.

The objective of Chapters 4-6 was to quantify the role of psychiatric service dogs for post-9/11 military veterans with PTSD. Chapter 4 quantified the perceived importance, frequency of use, and therapeutic value of service dog behaviors for N=216 military veterans with PTSD. Chapters 5 and 6 then quantified the effects that PTSD service dogs on psychosocial outcomes and physiological indicators of functioning, respectively, among a sample of N=141 military veterans with PTSD. Results identified therapeutic components, tangible psychosocial benefits, and potential physiological mechanisms of psychiatric service dogs for military veterans with PTSD.