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A Transcriptomic Analysis Of Salmonella Enterica Newport In Planta And After Postharvest Sanitization, Laurel Lynn Dunn Aug 2017

A Transcriptomic Analysis Of Salmonella Enterica Newport In Planta And After Postharvest Sanitization, Laurel Lynn Dunn

Doctoral Dissertations

The consumption of fresh produce is increasingly linked to incidence of foodborne illness. Pathogens including Salmonella enterica, Shiga toxigenic Escherichia coli, and Listeria monocytogenes are exposed to produce crops through direct human or animal contact, contaminated agricultural water, bioaerosols, run-off, and improperly treated compost. S. enterica has demonstrated exceptional tolerance to the stresses encountered in the environment, on plant tissue, and from postharvest antimicrobial mitigation strategies. Understanding the transcriptomic mechanisms S. enterica employs to survive these hazards is integral for the development of more effective preventive controls and post-harvest steps to prevent the pathogen from infecting consumers.


Structuring Solid/Oil/Water Emulsions To Deliver Water-Soluble Bioactive Food Ingredients, Yun Zhang May 2016

Structuring Solid/Oil/Water Emulsions To Deliver Water-Soluble Bioactive Food Ingredients, Yun Zhang

Doctoral Dissertations

Numerous delivery systems are studied for lipophilic bioactive compounds, but much work is needed for bioactive food ingredients soluble or dispersible in water. The overall hypothesis of this dissertation is that structured solid/oil/water (S/O/W) emulsions can be used to encapsulate water-soluble/dispersible ingredients to retain their release during processing and storage and control their release during simulated digestions. The encapsulation principle is to prepare spray-dried powder of water-soluble/dispersible compounds as the solid core that is coated by an oil layer emulsified by food biopolymers. The oil layer isolates the compounds from the continuous aqueous phase ...


Improving Antimicrobial Activity Of Lauric Arginate By Combination With Essential Oils For Novel Applications, Qiumin Ma Aug 2015

Improving Antimicrobial Activity Of Lauric Arginate By Combination With Essential Oils For Novel Applications, Qiumin Ma

Doctoral Dissertations

Lauric arginate (LAE) and essential oils (EOs) are highly efficacious in broth media but are required at much higher concentrations in food products to inhibit foodborne pathogens. Because high levels of LAE and EOs affect organoleptic properties of food products, this dissertation was studied for the potential of lowering their usage concentrations by using them in combination. Antimicrobial activities of LAE and EO used alone or in combination were characterized in Chapter 2. Synergistic and antagonistic effects of LAE-EO combinations and cinnamon leaf oil/eugnol/thymol were observed for inhibiting Gram-positive Listeria monocytogenes and Gram-negative Salmonella Enteritidis and Escherichia coli ...


Self-Assembled Casein Nanostructures To Deliver Novel Functionalities, Kang Pan Aug 2015

Self-Assembled Casein Nanostructures To Deliver Novel Functionalities, Kang Pan

Doctoral Dissertations

The nanoscale micellar structure of caseins can be manipulated by mechanical forces, solvent quality, and pH to reduce turbidity, encapsulate hydrophobic compounds, and improve dispersion stability and rheological properties. The goal of this dissertation was to control the nanostructure of self-assembled caseins to deliver functionalities. The combination of treatments at pH 11.0 and acidification with citric acid was first studied to produce translucent skim milk dispersions at pH 5.5-7.0, resulting from the significantly reduced dimensions of reassembled casein nanoparticles. Using sodium caseinate (NaCas), soluble soybean polysaccharide (SSPS), and high-speed homogenization, a food grade delivery system was studied ...


Salmonella In Low Water Activity Foods: Physiological, Genetic Modification And Control Methods, Wei Chen Aug 2015

Salmonella In Low Water Activity Foods: Physiological, Genetic Modification And Control Methods, Wei Chen

Doctoral Dissertations

The objective of this study was to evaluate the expression of fatty acid associated genes (fabA, fabD and cfa) of five serovars of Salmonella exposed to sugar over a 14-day period. Changes in the fatty acid composition of Salmonella Tennessee in glycerol solutions of different water activity (aw) (1.0-0.6) and the relationship between survival and fatty acid modification (as altered by exogenously supplied fatty acids) at aw 1.0-0.6 were also determined. Furthermore, the antimicrobial activities of carvacrol, cinnamaldehyde, and lauric arginate (LAE) alone or in combination against Salmonella Tennessee in a laboratory model of ...


Blueberry Polyphenols As Natural Antimicrobial Agents Against Foodborne Viruses: Towards Understanding Their Mechanism And Applications In Food Systems, Snehal Shrikant Joshi Aug 2015

Blueberry Polyphenols As Natural Antimicrobial Agents Against Foodborne Viruses: Towards Understanding Their Mechanism And Applications In Food Systems, Snehal Shrikant Joshi

Doctoral Dissertations

Foodborne viruses are recognized as public health concerns worldwide and therefore effective strategies to control their spread are being researched. Blueberries are known for their health benefits and antimicrobial properties. This study aimed to (1) determine the antiviral effects of blueberry juice (BJ) and blueberry proanthocyanidins (B-PAC) against the infectivity of hepatitis A virus (HAV), Aichi virus (AiV) and human norovirus surrogates (feline calicivirus (FCV-F9) and murine norovirus (MNV-1)) at 37oC over 24-h using standard plaque assays; (2) evaluate antiviral effects in model foods (apple juice (AJ) and 2% milk) and simulated gastrointestinal conditions at 37oC ...


Thermal Inactivation Of Shiga Toxin-Producing Escherichia Coli In Foods, Malcond David Valladares May 2015

Thermal Inactivation Of Shiga Toxin-Producing Escherichia Coli In Foods, Malcond David Valladares

Doctoral Dissertations

Emerging non-O157 Shiga toxin-producing Escherichia coli (STEC) were recently added to the zero tolerance policy by the USDA-FSIS. Therefore, the precise characterization of their thermal inactivation kinetics in different foods and the effect of stress on thermal inactivation are needed. This research aimed at determining the heat inactivation kinetics of non-O157 and O157 STECs in buffer and model food matrices and the effects of DnaK levels on thermal resistance after acid and heat-shock. Thermal inactivation was carried out in either in 2-ml glass vials or nylon vacuum-sealed bags for buffer and food (spinach, ground-beef, turkey deli-meat, pasta) samples, respectively. Vials ...


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 ...


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 ...


Whey Proteins Cross-Linked By Transglutaminase Or Glycated With Maltodextrin: Physicochemical Bases Of The Improved Heat Stability, Wan Wang Dec 2013

Whey Proteins Cross-Linked By Transglutaminase Or Glycated With Maltodextrin: Physicochemical Bases Of The Improved Heat Stability, Wan Wang

Doctoral Dissertations

Whey protein, as a byproduct in cheese manufacturing, is an ideal source for producing ready-to-drink protein beverages for different market demands, attributed to its high content of essential amino acids and versatile functionalities, bland flavor and good digestibility. Whey protein is a mixture of proteins, which can be categorized into whey protein concentrate (WPC) with a protein content of 50~80% and whey protein isolate (WPI) with a protein content higher than 90%, depending on different separation techniques. Thermal processing is required to ensure microbiological safety and quality of dairy products, leading to denaturation of whey proteins, especially at pH ...


Design And Development Of Seed Hydration Analyzing Device And Its Utilization In Studying Cereal And Legume Hydration, Vinay Kumar Mannam Dec 2013

Design And Development Of Seed Hydration Analyzing Device And Its Utilization In Studying Cereal And Legume Hydration, Vinay Kumar Mannam

Doctoral Dissertations

Cereals and legumes are important sources of vegetable-based human nutrition. Together they account for 48.6 % of protein and 8.7 % carbohydrate consumption around the world. During preparation, majority of these agricultural staples are re-hydrated to aid in their digestibility, palatability and the bio-availability of the nutrients.

Study of hydration kinetics of cereals and legumes is an important and valuable necessity for industry and academia to understand and gain insights into seed hydration characteristics. An automatic seed hydration analyzing system is developed as a solution for lack of instruments with broad capabilities to study variety of seed properties. The device ...


Isolation, Antibiotic Resistance, And Molecular Characterization Of Campylobacter From Poultry, Swine And Dairy Cows, Willie James Taylor Dec 2012

Isolation, Antibiotic Resistance, And Molecular Characterization Of Campylobacter From Poultry, Swine And Dairy Cows, Willie James Taylor

Doctoral Dissertations

This study was conducted to determine presence, antibiotic resistance, and genetic relatedness of Campylobacter on diverse farm types. Cloacal fecal samples from poultry (broilers, layers, and turkey breeders), and fecal rectal samples from non-poultry animals (farrowing sows, finisher pigs, and lactating dairy cows) were tested for Campylobacter using BAM protocols. Agar disk diffusion method was used to determine antibiotic resistance, and PFGE analysis to determine genetic relatedness of isolates recovered within the different farm types. Campylobacter was detected in 34.8% (range of 6.7 to 62.0%, P < 0.001) of cloacal samples from poultry, in 61.4% (range of 55.0 to 69.0%, P < 0.05), and 26.0% (range of 19.0 to 34.0%, P < 0.05) of rectal samples from pigs, and dairy cows, respectively. Antibiotic resistance was detected in 30.2% (range of ...


Casein Micelles From Bovine Milk: Native Structure, Interactions, And Practical Applications Of Their Structural Modification, Raymundo Trejo Dec 2012

Casein Micelles From Bovine Milk: Native Structure, Interactions, And Practical Applications Of Their Structural Modification, Raymundo Trejo

Doctoral Dissertations

A definitive structure of the native casein micelle structure continues to elude researchers. Data and images obtained via cryo - transmission electron microscopy of isolated native casein micelles allowed for the reconstruction of a three dimensional model of the micelle; which contains water filled cavities (ca. 20 to 30 nm diameter), channels (diameter larger than ca. 5 nm), and several hundred high density nanoclusters (6-12 nm diameter) within the interior of the micelles.

The SDS polyacrylamide gel electrophoresis of isolated micelles (pH 6.8, 5.0) showed that whey proteins were found associated with the isolated micelles regardless of the pH ...


Novel Rapid Molecular Detection And Processing Approaches For The Control Of Salmonella Enterica Serovars In The Food Environment, Chayapa Techathuvanan May 2012

Novel Rapid Molecular Detection And Processing Approaches For The Control Of Salmonella Enterica Serovars In The Food Environment, Chayapa Techathuvanan

Doctoral Dissertations

The increase in Salmonella enterica outbreaks calls for an urgent need to rapidly detect and control Salmonella-associated contamination. Loop-mediated isothermal amplification (LAMP) assay is a novel method that can be completed within 90 min in a simple waterbath. Detection is by simple turbidity, fluorescence, or gel electrophoresis and is more specific than PCR. Reverse-transcriptase LAMP (RT-LAMP) targeting mRNA for the potential detection of live infectious Salmonella or recent contamination was used in this study and detection sensitivity to culture-based detection and RT-PCR assays was compared in pure culture, food products, and food processing environments. Our results showed detection limits ...


Plant Protein-Based Nanocomposite Materials: Modification Of Layered Nanoclay By Surface Coating And Enhanced Interactions By Enzymatic And Chemical Cross-Linking, Minfeng Jin May 2012

Plant Protein-Based Nanocomposite Materials: Modification Of Layered Nanoclay By Surface Coating And Enhanced Interactions By Enzymatic And Chemical Cross-Linking, Minfeng Jin

Doctoral Dissertations

Highly intercalated or exfoliated nanoclay montmorillonite (MMT) has promises to improve mechanical and barrier properties of nanocomposite materials that may be further improved by strengthening interactions between matrix polymers and nanofillers. In this work, water-soluble proteins extracted from hominy feed and soy flour were utilized to modify the structures of MMT layers by surface-coating. Following coating at 60 °C using different MMT:protein mass ratios (49:1-2:1) and pH (2.0-10.0), the nanoclay was triple-washed for zeta potential analysis and lyophilized for X-ray diffraction and Fourier transform infrared spectroscopy analyses. Results showed that protein adsorption on MMT occurred ...


Nano-Dispersing Lipophilic Antimicrobials For Improved Food Safety, Bhavini Dipak Shah Dec 2011

Nano-Dispersing Lipophilic Antimicrobials For Improved Food Safety, Bhavini Dipak Shah

Doctoral Dissertations

Naturally occurring food antimicrobials such as plant essential oils are receiving tremendous interest as intervention systems to enhance microbiological safety and quality. Poor water solubility of essential oils makes it difficult to incorporate them in foods, impacting visual appearance, antimicrobial effectiveness, and possibly organoleptic properties. Engineered nanoscale delivery systems can principally solve these challenges, but those based on low-cost food ingredients and inexpensive and scalable processes are currently scarce. This dissertation presents a simple and scalable two-step technology to prepare nano-delivery systems. The first encapsulation step, based on emulsion-evaporation, involves preparing emulsions composed of an oil phase with thymol or ...


Antimicrobial Activity Of Aqueous Yerba Mate Extracts, Kellie Parks Burris May 2011

Antimicrobial Activity Of Aqueous Yerba Mate Extracts, Kellie Parks Burris

Doctoral Dissertations

Ilex paraguariensis, is used in the preparation of a widely popular tea beverage (Yerba Mate) mainly produced and consumed in the countries of Uruguay, Paraguay, Argentina and Brazil. Dialyzed aqueous extracts were screened for antimicrobial activity against Escherichia coli O157:H7, Staphylococcus aureus, methicillin-resistant S. aureus and S. pseudintermedius, and Pseudomonas syringae pv. tomato.

Using a concentrated extract, S. aureus was found to be the more sensitive to extracts than E. coli O157:H7. Minimum inhibitory concentration (MIC) was defined as the lowest concentration of extract tested that did not allow bacterial growth (inhibition) above the original inoculums of approximately ...


Novel Delivery Systems Of Nisin To Enhance Long-Term Efficacy Against Foodborne Pathogen Listeria Monocytogenes, Dan Xiao Dec 2010

Novel Delivery Systems Of Nisin To Enhance Long-Term Efficacy Against Foodborne Pathogen Listeria Monocytogenes, Dan Xiao

Doctoral Dissertations

Novel intervention strategies such as food grade antimicrobials are used to enhance food safety. Nisin is a widely used naturally occurring antimicrobial effective against many pathogenic and spoilage microorganisms. However, its antimicrobial efficacy in food matrices is much reduced because of interactions with food components. Novel delivery systems may overcome this problem by protecting nisin in capsules and releasing it in a controlled manner. The overall goal of this research was to develop delivery systems of nisin to improve its long-term antimicrobial effectiveness. The first objective was to develop a low-cost method to extract nisin from a commercial preparation containing ...


The Casein Micelle As An Encapsulation System For Triclosan: Methods Of Micelle Dissociation, Encapsulation, Release, And In Vitro Delivery, Adrienne L. Roach Dec 2009

The Casein Micelle As An Encapsulation System For Triclosan: Methods Of Micelle Dissociation, Encapsulation, Release, And In Vitro Delivery, Adrienne L. Roach

Doctoral Dissertations

This dissertation reports on the use of the casein micelle as an encapsulation and potential delivery system for a low molecular weight hydrophobic compound, triclosan. The ability of the casein micelle to serve in this capacity was tested in a series of experiments investigating: 1) micelle dissociation to expose hydrophobic binding sites of interaction, 2) encapsulation of triclosan, 3) the release of triclosan under various conditions, and 4) the intercellular delivery of triclosan to human liver cells in vitro for the inactivation of a malaria-causing parasite. Casein micelle dissociation and reassociaiton was achieved through high pressure homogenization and solvent-mediated pressure-induced ...


Characterization And Performance Improvement Of Chitosan Films As Affected By Preparation Method, Synthetic Polymers, And Blend Ratios, Jiajie Li Aug 2008

Characterization And Performance Improvement Of Chitosan Films As Affected By Preparation Method, Synthetic Polymers, And Blend Ratios, Jiajie Li

Doctoral Dissertations

Chitosan films prepared with addition of other polymers have been widely studied for their modified properties. In this dissertation, poly (ethylene oxide) (PEO) and poly (N-vinyl-2- pyrrolidone) (PVP) were blended with chitosan. The objectives of the study were (1) to investigate the the effects of film thickness, blend ratios, and preparation methods on the physical, and mechanical properties and functional performance of chitosan/PEO films, and (2) to compare characteristics and functional properties of chitosan/PVP and chitosan/PEO films.

The results demonstrated that regular cast chitosan/PEO films have altered properties than films produced from either polymer alone. Regardless ...


Analysis And Application Of Key Modeling Concepts Utilized In Predictive Microbiology For Food Processing, Darryl G. Black May 2008

Analysis And Application Of Key Modeling Concepts Utilized In Predictive Microbiology For Food Processing, Darryl G. Black

Doctoral Dissertations

The use of modeling techniques for safety and risk prediction in the food supply is a common practice. Factors affecting microbial heat resistance include those inherent to the organism, environmental conditions and the intrinsic properties of the heating menstruum. Varying physiological states of microorganisms could affect the measured response and add uncertainty to results from predictive models. Inactivation tests were performed using Escherichia coli strain K12 and E. coli O157:H7 for various growth conditions: traditionally or statically grown cells, chemostat‐grown cells, and chemostatgrown cells with buffered feed media. Heating menstruum was non‐buffered 0.1% peptone, 0.1 ...


Enterobacter Sakazakii Growth Profile And Tolerance To Chlorine Sanitizers, Diana Carolina Naar Cifuentes May 2008

Enterobacter Sakazakii Growth Profile And Tolerance To Chlorine Sanitizers, Diana Carolina Naar Cifuentes

Doctoral Dissertations

Enterobacter sakazakii is considered an emerging opportunistic pathogen associated with sporadic life-threatening bacterial infections in neonates linked to the compsumption of contaminated infant formula [Stoll et al., 2004]. In 2001 a neonate fatal infection associated with the presence of E. sakazakii in infant formula occurred in the neonatal intensive care unit (NICU) of the University of Tennessee Hospital [Himelright et al., 2002], as a result of this outbreak, the hospital made several policy changes and requested the Food Safety Center of Excellence of University of Tennessee to analyze the growth pattern of this microorganism at the conditions maintained in the ...


The Stability Of Carotenogenic Food Colorants And Strategies To Prolong The Shelf Life In Process Cheese Spread, Ann Marie Doneski Craig Dec 2007

The Stability Of Carotenogenic Food Colorants And Strategies To Prolong The Shelf Life In Process Cheese Spread, Ann Marie Doneski Craig

Doctoral Dissertations

Food quality is often times measured by the way one perceives the food, particularly with respect to color and texture. Color quality often pre-determines expectation making it an important parameter to understand. The same can be said for textural properties of food. Maintaining color and texture are just two ways in which the shelf-life of food can be measured. One particular product that has experienced problems in this area is processed cheese spread in which the US military uses as part of the Meal, Ready-to-Eat (MRE) rations. The cheese spread is one of the most highly accepted products in the ...


Gene Expression Analysis Of Escherichia Coli O157:H7 At 10 And 37°C And Under Acidic Conditions Using High Density Oligonucleotide Microarrays, Kristina K. Carter Dec 2007

Gene Expression Analysis Of Escherichia Coli O157:H7 At 10 And 37°C And Under Acidic Conditions Using High Density Oligonucleotide Microarrays, Kristina K. Carter

Doctoral Dissertations

This purpose of this investigation was to use DNA microarrays to study gene expression in E. coli O157:H7 under refrigerated and acidic conditions. Total RNA from E. coli O157:H7 grown to 7 log CFU/mL under control (37 °C, pH 7), refrigerated (10°C, pH 7), acid adapted (37°C, pH 5.5, then lowered to 3.5), and acid shocked (37°C, pH 7, then lowered to 3.5) conditions was extracted using an optimized Qiagen RNeasy procedure. Total RNA was converted to cDNA, labeled, and hybridized onto an Affymetrix GeneChip® E. coli Genome 2.0 Array ...


Sonochemical And Hydrophobic Modification Of Chitin And Chitosan, Tao Wu Dec 2007

Sonochemical And Hydrophobic Modification Of Chitin And Chitosan, Tao Wu

Doctoral Dissertations

Chitin and chitosan are linear polysaccharides consisting of acetyl-glucosamine and glucosamine units with many potential applications in biomedicine, agriculture and food industry. In the food industry, chitosan can be used as antimicrobial agent and to create active packaging to improve food quality and extend shelf life. Commercial applications of chitosan are closely associated with its functional properties and biological activity, which are primarily governed by two structural properties: degree of acetylation (DA) and molecular weight (MW). The overall goal of this study was to develop methods for tailored modification of DA, MW and functionalities of chitosan.

The research was conducted ...


Application Of Solid Phase Micro-Extraction With Gas Chromatography-Mass Spectrometry For The Determination Of Geosmin And 2-Methylisoborneol In Processed Navy Beans (Phaseolus Vulgaris), Coesha Ancoinette Fairley Aug 2007

Application Of Solid Phase Micro-Extraction With Gas Chromatography-Mass Spectrometry For The Determination Of Geosmin And 2-Methylisoborneol In Processed Navy Beans (Phaseolus Vulgaris), Coesha Ancoinette Fairley

Doctoral Dissertations

This investigation was conducted to address the issue of musty bean products. The main objectives of this study were to: (1) identify the source of the musty, off-flavor in processed navy beans, (2) determine and identify the associated off-flavor compounds (geosmin and 2-methylisoborneol (2-MIB)), and (3) isolate the microorganism(s) responsible for production of the compounds.

To confirm the presence of geosmin and 2-MIB in processed baked beans, an automated gas chromatographic method employing solid phase micro-extraction (SPME-GC-MS) was used. Artificially musty baked beans, known musty beans, and raw ingredients (bacon, navy beans, and water) were analyzed. Results of this ...


Development Of A Real-Time Pcr Assay For Detection And Quantification Of Escherichia Coli O157:H7 In Apple Juice, Nancy Rabalais Detrana May 2007

Development Of A Real-Time Pcr Assay For Detection And Quantification Of Escherichia Coli O157:H7 In Apple Juice, Nancy Rabalais Detrana

Doctoral Dissertations

Apple cider/juice contaminated with Escherichia coli O157:H7 has been implicated in several foodborne illness outbreaks, but due to the presence of reaction inhibitors, detection by polymerase chain reaction (PCR) is often difficult. The studies presented in this dissertation were conducted to evaluate techniques to improve detection of E. coli O157:H7 in apple juice using a fluorogenic probe-based real-time PCR assay without prior enrichment. Two commercial DNA extraction and purification procedures, GenEluteTM Bacterial Genomic DNA Kit and PrepMan® Ultra Sample Preparation Reagent, were combined with two real-time PCR chemistries, SYBR® Green I dye and TaqMan® probes for potential ...