Life Sciences Commons^™

Modeling For Thermal Resistance Of Non-O157 Shiga Toxin Producing Escherichia Coli In Ground Beef, Jagpinder S. Brar

Open Access Dissertations

Predictive models in microbiology are used for estimating the growth or survival of microorganism in a set of environmental conditions. A validated predictive model provides an alternative to extensive survival and shelf life studies. In this study, a predictive inactivation model for non-O157 shiga toxin producing Escherichia coli (STEC) in ground beef was developed. Six strains of non-O157 STEC; E. coli O26:H1, E. coli O45:H2, E. coli O103:H2, E. coli O111:H8, E. coli O121:H9, and E. coli O145: nonmotile, has similar pathogenicity as E. coli O157:H7 and can cause serious food borne illnesses. These pathogens are considered as an adulterant …

Complex Glycan Utilization Preferences Of Human Gut Bacteria, Yunus Emre Tuncil

Open Access Dissertations

Complex glycans, making up dietary fiber, have gained significance in recent years as they are the main energy source for the colonic microbiota which are physiologically important for the host health. Understanding glycan utilization strategies of the members of this community is essential to maximize beneficial health outcomes obtained from them. In order to investigate how the members of our gut microbiota utilize glycans and activate their respective polysaccharide utilization loci (PULs), we performed a series of time-course assays in which two model organisms, Bacteroides thetaiotamicron (Bt) and B. ovatus (Bo), were individually grown in a medium containing carbohydrates utilized …

Influence Of Dietary Polyphenols On Carbohydrate Intestinal Digestion And Absorption, Sydney E. Moser

Open Access Dissertations

Both epidemiological and clinical evidence support the notion that polyphenol rich foods and beverages may modify glycemic response, glucose homeostasis and subsequent risk of Type-2 diabetes. In vitro evidence typically derived from experiments with pure phenolics and phenolic rich extracts have pointed to this benefit being associated with two potential mechanisms: (1) the ability of specific polyphenolics to inhibit carbohydrate digestion (amylase and glucosidase) and (2) polyphenolic inhibition of intestinal glucose transport. While the high potential of these activities is evident, little is actually known regarding the extent to which these benefits are extendable to the actual food matrix these …

Mitigating Prevalence And Persistence Of L. Monocytogenes Using Novel Sanitation Strategies In Delis, Susan Rose Hammons

Open Access Dissertations

Ready-to-eat (RTE) deli meats sliced at retail are predicted to cause 83% of deli meat-associated listeriosis cases annually. While L. monocytogenes is commonly found in delis (55-90%), environmental prevalence varies by store (0-40%). Study 1 evaluated efficacy of 10 standardized SSOPs by testing 28 food and non-food contact surfaces for L. monocytogenes over 6 months in 30 retail delis. Intervention strategies employed in this study significantly decreased L. monocytogenesprevalence on FCS and NFCS in stores with moderate prevalence (0.5%, 0.8% reduction). However, we found that L. monocytogenes could persist despite implementation of SSOP control strategies. Study 2 assessed an …

Transcriptional Stress Response In Foodborne Pathogens, Aaron M. Pleitner

Open Access Dissertations

Novel molecular method use is leading to better identification and understanding of microbial presence in food and food processing environments. The application of molecular methods targeting foodborne pathogens provides genetic profiling and targeted intervention methods. Whole-genome sequencing (WGS) provides information on the genomic uniqueness of specific pathogens and is being implemented in epidemiological investigations. Transcriptomic profiling allows for tracking the differential expression of genes and elucidating stress responses. Effective methods and treatments require an understanding of intervention (e.g. sanitizers) and treatment (e.g. antibiotics) mechanisms and efficacies. Accurate novel molecular method use requires proper learning of theory and data management. ^ …

Dietary Carbohydrates Influence The Structure And Function Of The Intestinal Alpha-Glucosidases, Mohammad Chegeni

Open Access Dissertations

As the primary products of starch digestion by pancreatic α-amylase, maltooligosaccharides (including maltose) are the main substrates for the α-glucosidases at the intestinal brush border. Here, maltose was shown to induce the formation of a higher molecular weight (HMW) sucrase-isomaltase (SI) species in Caco-2 cells that sorts more quickly to the enterocyte surface to act as a digestive enzyme. As this finding suggested a maltose sensing ability of small intestinal enterocytes, molecular mechanisms associated with the maturation and trafficking of HMW SI were further investigated. A pulse-chase experiment using [ ³⁵S]-methionine revealed a higher rate of early trafficking and …

African Starchy Foods, Gastric Emptying, And Starch Digestion In Malian Stunted Children, Fatimata Cisse

Open Access Dissertations

Starch serves as the main energy source in cereal and tuber-rich diets, and its glycemic response profile has been associated with health-related conditions. Sorghum and millet are known to have relatively low starch digestibility, a potentially desirable property for controlling blood glucose response and providing sustained energy. Gastric emptying rates of traditional sorghum and millet-based African foods of the Sahelian region (couscous, thick and thin porridges made from millet and/or sorghum) were compared to those of non-traditional "modern" foods that are mostly consumed in urban areas using a non-invasive 13C-labelled octanoic acid breath test in healthy volunteers. The obtained results …

Brain Bioavailability Of Polyphenols: Implications For Delivery Of Brain Health Benefits, Tzu-Ying Chen

Open Access Dissertations

Consumption of fruits and vegetables has been associated with neuroprotection and cognitive benefits throughout the life span. These associations have sparked interest in plant-derived polyphenols as biologically active agents with potential for targeting brain benefits. However, little is known regarding the ability of the polyphenols or their metabolites from polyphenol-rich products to cross the blood-brain-barrier, and be available for biological action. Furthermore, additional insight is needed on factors affecting the absorption and brain distribution of polyphenol metabolites in vivo. To fill gap in current knowledge, this thesis will focus on the effects of diabetogenic diet and diabetic state which have …

Using X-Ray Imaging Techniques To Determine Density Of Foods, Shivangi Mohan Kelkar

Open Access Dissertations

Density depends on the experimental technique and structural properties of food. True, apparent and bulk are different types of densities. For porous foods such as baked food products and complex food systems, accurate measurement of density is challenging. Empirical correlations dependent on composition and temperature exist to calculate true density. Thus if composition and apparent density are known, porosity can be calculated, porosity = [1 - (apparent density/ true density)]. Various non-destructive diagnostic tools have been employed to study food microstructure. Among these, computed tomography (CT) and digital radiography (DR) utilizing x-ray imaging showed greater capability for evaluation of food …

The Chemistry Of Flavonoids In Model Beverages And Human Milk, Brian Jay Song

Open Access Dissertations

Interest in the chemistry and stability of flavonoids in foods has been generated by countless epidemiological, in vitro, and in vivo studies that suggest a variety of potential health promoting effects of diets rich in flavonoids. Flavonoids have been shown to interact with multiple components in beverages including macromolecules, minerals, certain vitamins, and other flavonoids. Furthermore, environmental conditions including light exposure, elevated temperatures, and relative humidity have been shown to modify flavonoid stability. However, specific mechanisms, relative kinetics of degradation reactions and the impact of macromolecules in model beverages and biological fluids on flavonoid stability remain largely unknown.

Recently, interest …

Invasive Silver Carp (Hypophthalmichthys Molitrix) Protein Hydrolysates- A Potential Source Of Natural Antioxidant, Sravanthi Priya Malaypally

Open Access Dissertations

Invasive silver carp (Hypophthalmichthys molitrix), continue to spread over the Mississippi River causing a great concern for the river ecosystem due to their impact on native fish species. To minimize the negative effects of silver carp, many strategies were implemented including using it for animal feed, as fertilizers or simply discarding them into waste. However, these fish are high in protein content, making them excellent starting material for protein-derived by-products. One alternative is to recover and modify the protein in the fish into bioactive food ingredient. In the functional/ nutraceutical food industry, there is high demand for antioxidant agents. In …