Life Sciences Commons^™

Novel Method For Recovery Of Escherichia Coli O157:H7 From Beef Surfaces, Matthew Adam Becher

Masters Theses

A study was conducted to compare the efficiency of detection of Escherichia coli O157:H7 EDL 933 on external beef trim by commercial recovery systems based upon of the Microbial-Vac System (M-Vac) and excision sampling. Escherichia coli O157:H7 EDL 933 was cultured in tryptic soy broth for 24 hr at 37°C and transferred for three consecutive days before diluting and spot inoculating onto a 684 cm² piece of beef trim (10 CFU/684 cm²). Beef trim was sampled with the M-Vac by passing the sampling head over the entire surface area in a vertical sampling pattern. The sampling head …

“Intervention Strategies To Enhance The Safety Of Ready-To-Eat Meat Products By Plant Essential Oils, Chayapa Techathuvanan

Masters Theses

Components of plant essential oil (PEO) extracts are known to have antimicrobial properties. However, their antimicrobial efficacy in food systems is low due to their hydrophobic nature and association with other food components. Incorporation of PEO components into an appropriate carrier may offer a potential solution to improve their activity in food systems. This study was conducted to determine the effect of PEO components (thymol, eugenol, linalool, carvacrol, and cinnamaldehyde) incorporated into zein coating on inactivation of Listeria monocytogenes on a ready-to-eat meat model, frankfurters (hot dogs). Hot dogs were inoculated with 7 log CFU/sample and dipped into prepared PEO-zein …

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 of molecular weight, chitosan …

Mechanisms Of Calcium-Induced Firmness In Fruits, Vegetables, And Mushrooms, Xiaoyun Deng

Masters Theses

Six fractions from mushrooms (MFs), as cytoplasmic proteins (F1), cell membrane proteins (F2), alkali-soluble cell wall glucans (F3a), cell wall proteins (F3b), cell wall beta-glucans (F4a), and chitin (F4b) and five fractions from both apples (AFs) and cucumbers (CFs), as cytoplasmic proteins (F1), cell membrane proteins (F2), cell wall proteins (F3), pectic substances (F4), and cellulose (F5) were extracted and analyzed for their neutral carbohydrates, proteins, aminosugar material, soluble phenolics, and pectic substances. The dominant compounds consisted of the following: proteins in MF1, proteins and neutral polysaccharides in MF2, neutral polysaccharides in MF3a, neutral polysaccharides in MF3b, neutral polysaccharides and …

Sustained Release Of Lysozyme Encapsulated In Zein Micro- And Nanocapsules, Minfeng Jin

Masters Theses

A hydrophobic biopolymer, corn zein, was studied as a carrier for manufacturing particulate delivery systems of antimicrobials with sustained release. Three techniques, i.e., solvent attrition, supercritical anti-solvent and spray drying, were investigated to produce lysozyme-loaded zein micro- or nanocapsules. The work was focused on particle synthesis and in vitro release kinetics as affected by formulations and processes.

The size (100-200 nm) and morphology (separated or connected) of the zein nanoparticles produced using solvent attrition were significantly affected by shear force, ethanol and zein concentrations in stock solutions during synthesis. Zein nanoparticles showed gradual release of lysozyme at pH 7 and …

Application Of High Pressure Homogenization And Ultrafiltration For The Manufacture Of Skim Milk Acid Gels And Isolation Of Casein, Aarón Hernández

Masters Theses

The dairy industry has experienced an important growth around the world in the last decades. Along with this growth, advances in scientific research and technology have opened the possibility for new applications of dairy products. These topics are discussed in Chapter I as a literature review and introduction.

Emerging non-thermal technologies can offer many advantages when compared to thermal technologies. High Pressure Homogenization (HPH) is an emerging technology applied in the study of dairy science. Chapter II of this thesis describes the study of HPH (0-350 MPa) in combination with thermal processing (90°C, 5 min) to improve the rheological properties …

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 M phosphate buffer (pH 7.0), …

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 …

Characterization Of Food Safety Knowledge, Attitudes, And Behaviors Of Adolescents In East Tennessee, Ashley S. Pedigo

Masters Theses

Educational research suggests that middle school is an ideal time to teach food safety since adolescents are in the process of setting life-long behaviors and are, therefore, more likely to synthesize new food safety knowledge into positive behaviors.

The objectives of this study were to: 1) Describe the baseline food safety knowledge and attitudes/ behaviors of 7^th grade students in East Tennessee 2) determine the relationship with geographic location, socioeconomic status, race, and gender; and 3) compare the current data (Study 2) to a previous study (Study 1) that pre-tested 7^th grade students prior to an education intervention. …