Open Access. Powered by Scholars. Published by Universities.®

Life Sciences Commons

Open Access. Powered by Scholars. Published by Universities.®

Articles 1 - 11 of 11

Full-Text Articles in Life Sciences

Absorption And Utilization Of Choline And Vitamin B12 In Lactating Dairy Cows Using Different Delivery Methods, Virginia Maria Artegoitia Etcheverry Dec 2014

Absorption And Utilization Of Choline And Vitamin B12 In Lactating Dairy Cows Using Different Delivery Methods, Virginia Maria Artegoitia Etcheverry

Doctoral Dissertations

Choline and vitamin B12 are essential nutrients for growth and performances of production animals. However, both nutrients are extensively degraded during digestion in the rumen. This thesis comprised three experiments. First, four cows equipped with a rumen cannula and catheters in the portal vein and a mesenteric artery received a post-ruminal bolus of: 1) cyanocobalamin (CN-CBL) alone (0.1 g) [gram], 2) CN-CBL (0.1 g) + casein (10 g) or 3) CN-CBL (0.1 g) + whey proteins (10 g). After the bolus, blood samples were taken until 24 h [hour] post-bolus. The intestinal absorption of CN-CBL was greater when the ...


An Epidemiological Study Of Campylobacter Populations Reveals A Selective Pressure By Roxarsone, Sean Jeffery Pendleton Dec 2014

An Epidemiological Study Of Campylobacter Populations Reveals A Selective Pressure By Roxarsone, Sean Jeffery Pendleton

Doctoral Dissertations

Whole genome sequencing (WGS) is the most discriminatory of typing methods and can provide additional information including virulence, antigen targets for vaccine development, and antimicrobial resistance profiles. The first part of this study aimed to determine the application of WGS as a genotyping method for Campylobacter by comparing WGS to two commonly used genotyping methods, Pulsed-field gel electrophoresis (PFGE) and flaA typing. Five Campylobacter strains isolated from conventional and organic poultry, and five additional isolates with published genomes were compared using the three methods. A total of 8 PFGE patterns and 8 flaA alleles were identified from the 10 strains ...


Impact Of Surface Active Minor Components On Physicochemical Properties Of Association Colloids And Lipid Oxidation In Bulk Oil, Ketinun Kittipongpittaya Nov 2014

Impact Of Surface Active Minor Components On Physicochemical Properties Of Association Colloids And Lipid Oxidation In Bulk Oil, Ketinun Kittipongpittaya

Doctoral Dissertations

Lipid oxidation is a great concern for food manufacturers and consumers as it negatively impacts not only food quality and nutritive values of food lipids, but also consumer health. Lipid oxidation in bulk oil is impacted by chemical factors, such as, prooxidants and antioxidants, and is also related to the existence of physical structures. Bulk oils contain a variety of surface active minor components which are able to form physical structures known as association colloids. These physical structures create oil-water interfaces which seem to be an important site where lipid oxidation occurs in bulk oil. Thus, this research focused on ...


Influence Of Lipoteichoic Acid On Listeria Monocytogenes Biofilm Formation And Cellular Stress, Imelda T. Brooks Nov 2014

Influence Of Lipoteichoic Acid On Listeria Monocytogenes Biofilm Formation And Cellular Stress, Imelda T. Brooks

Doctoral Dissertations

Lipoteichoic acid (LTA) is an important polymer on the surface of Gram-positive organisms, including the foodborne, biofilm-forming pathogen Listeria monocytogenes, and is connected to the cell membrane through a glycolipid backbone. Previous results have shown the importance of LTA in cell viability and biofilm formation. The purpose of this research is to further investigate the influence of LTA in L. monocytogenes biofilm formation and how the bacterium responds to environmental stress caused by antimicrobial exposures, and a combination of low temperature and high osmolarity. We created in frame deletion mutants along the operon lmo-2555-lmo2554-lmo2553, which have been shown to reduce ...


Understanding Lipid Oxidation In Low-Moisture Food, Leann M. Barden Nov 2014

Understanding Lipid Oxidation In Low-Moisture Food, Leann M. Barden

Doctoral Dissertations

Low-moisture snacks account for much of the saturated fat in the diet, making them a key target for improving consumers’ health. However, it is not currently feasible to maintain the same shelf life when replacing saturated fats with unsaturated fats in these products.

The first study characterized the microstructure of a low-moisture cracker model system and determined the impact of iron, chelators, and free fatty acids (FFA) on lipid oxidation kinetics. Confocal microscopy showed that lipids form a continuous layer surrounding the small and/or minimally gelatinized starch granules. Lipid-starch, lipid-air, and starch-lipid-protein interfaces all existed. Oxidation studies showed a ...


Susceptibility Of Escherichia Coli O157:H7, Salmonella Enterica Sp., And Listeria Monocytogenes To Antimicrobial Mixed Micelle Delivery Systems, Chanelle N. Adams Nov 2014

Susceptibility Of Escherichia Coli O157:H7, Salmonella Enterica Sp., And Listeria Monocytogenes To Antimicrobial Mixed Micelle Delivery Systems, Chanelle N. Adams

Doctoral Dissertations

Within the food industry, there is an ever increasing demand to improve the quality of food and ensure safety from pathogenic/spoilage microorganisms. Globalization of the food industry in the 1990’s, in conjunction with the worldwide shipment of food created a need for the extension of shelf-life and enhanced maintenance of food quality (12). In the United States alone, the Centers for Disease Control and Prevention report that each year, roughly 1 in 6 Americans (or 48 million people) gets sick, 128,000 are hospitalized, and 3,000 die of foodborne diseases; this correlates to approximately $77.7 billion ...


Cancer Chemoprevention By Dietary Compounds Targeting Angiogenesis, Wasamon Nutakul Aug 2014

Cancer Chemoprevention By Dietary Compounds Targeting Angiogenesis, Wasamon Nutakul

Doctoral Dissertations

Cancer remains a leading cause of death worldwide. Due to angiogenesis and metastatic potency of cancer, chemotherapies are not adequate for metastatic tumor. We investigated anti-carcinogenic effects of resveratrol in comparison to those of pterostilbene in colon cancer cells. We found superior activities of pterostilbene over resveratrol in growth inhibition as well as apoptosis induction. Higher Intracellular concentration of pterostilbene could contribute to its higher potency in anti-carcinogenesis; however, both resveratrol and pterostilbene failed to inhibit colon cancer cell migration in vitro. Polymethoxylatedflavones (PMFs) found exclusively in citrus fruits have shown inhibitory effects against cancer. We investigated their anti-angiogenic activities ...


Fabrication Of Zein Nanoparticle-Biopolymer Complexes To Deliver Essential Oils In Aqueous Dispersions, Huaiqiong Chen Aug 2014

Fabrication Of Zein Nanoparticle-Biopolymer Complexes To Deliver Essential Oils In Aqueous Dispersions, Huaiqiong Chen

Doctoral Dissertations

Zein, alcohol-soluble corn proteins, easily precipitate as nanoparticles after dispersing a stock zein solution with a polar solvent into water. The process can be used to nanoencapsulate essential oils (EOs). However, the stability of hydrophobic zein nanoparticles is a challenge for their application in aqueous food systems. The goal of this dissertation reseach was to stabilize zein nanoparticles in aqueous dispersions by forming complexes with water-soluble biopolymers. The stabilization of zein nanoparticles was first studied using sodium caseinate by dispersing hot 50% aqueous ethanol solution with both polymers in water. The nanoparticles contained κ-casein and zein, and the spray-dried nanoparticles ...


Casein Micelles And Their Properties: Polydispersity, Association With Vitamin A And Effect Of Ultra-High Pressure Homogenization, Maneesha Sheenu Mohan Aug 2014

Casein Micelles And Their Properties: Polydispersity, Association With Vitamin A And Effect Of Ultra-High Pressure Homogenization, Maneesha Sheenu Mohan

Doctoral Dissertations

The internal structure of casein micelles is not fully understood. In the present work, we explore some of the basic questions about casein micelles in bovine milk including its size distribution, native binding properties and effect of ultra-high pressure homogenization (ultra-HPH) on technological properties of casein micelles. The size distribution of casein micelles was studied by cryo-TEM using skim milk from four cows. The degree of variation in casein micelle sizes (polydispersity) ranged between 0.39 and 0.47 for a size distribution ranging from 10 to 693 nm. These results indicated high polydispersity of casein micelles in milk from ...


Thermal Inactivation Of Human Norovirus Surrogates And Hepatitis A Virus In Foods, Hayriye Bozkurt Cekmer May 2014

Thermal Inactivation Of Human Norovirus Surrogates And Hepatitis A Virus In Foods, Hayriye Bozkurt Cekmer

Doctoral Dissertations

Foodborne enteric viruses are the leading cause of gastroenteritis in humans. In particular, human noroviruses and hepatitis A virus (HAV) are the most important foodborne viral pathogens with regard to the number of outbreaks and people affected. Therefore, studies are needed to bridge existing data gaps and determine appropriate parameters for thermal inactivation methods for human norovirus and hepatitis A virus. Due to the absence of appropriate cell culture systems to propagate these viruses, cultivable surrogates (feline calicivirus, FCV-F9 and murine norovirus, MNV-1) are commonly used based on the assumption that they can mimic the viruses they represent. The objectives ...


Development Of Capillary-Driven Microfludic Biosensors For Food Safety And Quality Assurance, Fei He Apr 2014

Development Of Capillary-Driven Microfludic Biosensors For Food Safety And Quality Assurance, Fei He

Doctoral Dissertations

Rapid detection technologies with high sensitivity and selectivity for pathogenic bacteria are critical in food safety and quality assurance. Traditional laboratory benchtop techniques (i.e. culture and colony counting) are time consuming and require complex sample handling. Microfluidics-based Lab-on-a-Chip (LOC) systems offer a detection alternative where all detection steps are on one portable miniaturized device. The miniaturization of rapid foodborne pathogen detection at a low cost is especially ideal for resource-limited settings or for field-use. The goal of this study was to develop a disposable miniaturized microfluidic device for on-site pathogen detection.

Capillary-driven microfluidics have been introduced in this study ...