Theses and Dissertations from UMD
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New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a give thesis/dissertation in DRUM
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Item The Establishment, Evaluation, and Validation of Operating and Working Parameters for an Analytical Method to quantify Polyphenolic Compounds using an Electrochemical Apparatus(2010) Blackford, Jessica; Yu, Liang Li; Food Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Polyphenols have health-beneficial antitumorigenic and antioxidative effects. This project evaluated the spectroelectrochemical responses to polyphenols for the development of an analytical polyphenolic method using an electrochemical apparatus. Operating parameters of 0.5 V and 1000 seconds were chosen after evaluations of cyclic voltammograms and durational response. Linearity was measured (R2: 0.96, caffeic acid; 0.94, protocatechuic acid; 0.93, gallic acid; over concentration range 0.5 - 5.0 mM), as were effects of ion strength (no baseline effect by buffer less than 1.0 M), and solvent composition (influence detected in non-aqueous solutions). Effects of ascorbic or monohydroxyphenolic acid on polyphenolic determinations by the electrochemical apparatus were compared to determinations by the Folin Ciocalteu (FC) method. Ascorbic acid exerted significant interference on electrochemical and FC measurements. Monohydroxyphenolic acids did not interfere with electrochemical polyphenol measurements, but significantly interfered with FC quantifications. This electrochemical apparatus may offer potential for the development of a quantitative assay for polyphenols.Item FEASIBILITY OF BINDING ANTIOXIDATIVE FOOD PIGMENTS USING RIBULOSE-1,5-BISPHOSPHATE CARBOXYLASE OXYGENASE(2010) Yachetti, Sarah M.; Lo, Y. Martin; Food Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Antioxidative food pigments during manufacturing are subjected to harsh conditions that can attenuate the antioxidant benefits and alter its color significantly. Thus, stabilization of these pigments is desired to increase the product's nutritional and commercial value. Ribulose-1, 5-bisphosphate carboxylase oxygenase (RuBisCO), an abundant protein with a balanced amino acid profile, may serve as a good binding agent to increase stability of pigments due to the fact that it is naturally bound to chlorophyll in plants besides its highly stable structure. This research investigated the binding capacity of purified RuBisCO to riboflavin, annatto extract, and beta-carotene. Protein-pigment complexes were promoted with mixing, sonicating, heating and freeze thawing techniques. Raman spectroscopy, surface plasmon resonance, and UV-Vis were used to measure binding potential. A method to extract RuBisCO from tobacco with paramagnetic antibody-coated beads was also investigated. Not only does this exploratory research provide the baseline understanding of the challenges and hurdles in forming a protein-pigment complex, but the detection techniques established could also be of value for developing quantitative measurements of such complexes. While further research is still needed to elucidate the interaction between the pigments and RuBisCO, it was confirmed that the binding ability of RuBisCo to the pigments investigated could be greatly hindered by the structural conformation of RuBisCo.Item FACTORS INFLUENCING MARYLAND FARMERS' ON-FARM PROCESSING LICENSE APPLICATION BEHAVIOR(2010) Lubran, Meryl; Kantor, Mark; Food Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)A 2005 regulation adopted by Maryland's state health department allowed farmers to sell foods processed in their home kitchen provided they complete an 8-hour food safety education course and apply for an on-farm processing license. Although more than 100 farmers completed the course, only 25 farmers applied for and received a license. The number of licenses granted has not met expectations and the health department is continually looking for ways to improve the program. The objective of this study was to identify factors that may influence Maryland farmers' intentions to apply for a license as well as their actual license application behavior using a model which combines two dominant theoretical paradigms - the Health Belief Model and the Theory of Planned Behavior. To test the proposed model, a mail survey was administered to farmers who completed the training, farmers who have an on-farm license, and to a systematic random sample of other Maryland farmers (n = 745). To explore reasons why the courses may not have encouraged more farmers to apply, a content analysis of the training presentations was conducted by two trained coders. The usable survey response rate was 15% (n = 110). Using structural equation modeling, the proposed model, predicting farmers' intentions to apply for a license, was found to have marginal fit. Significant direct relationships were found between farmers' attitudes, subjective norms, and their intentions. Significant indirect relationships were found between farmers' beliefs of perceived benefits and barriers and their attitudes. Using rare events logistic regression to predict license obtainment, and a multiple regression and two correlation analyses to test the proposed indirect relationships, the same relationships were found to predict actual behavior as behavioral intentions. An additional significant relationship was found between perceived behavioral control and behavior. Few differences were found between mean responses of farmers who did and did not attend the training. The content analysis of training materials revealed few persuasive strategies were utilized during training. These findings provide insight into factors affecting farmers' decisions to apply for an on-farm license, and suggest relevant factors, concerns, and issues to address in future educational outreach efforts.Item Pathogenic Escherichia coli in retail meats(2010) Xia, Xiaodong; Meng, Jianghong; Food Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Pathogenic Escherichia coli, including diarrheagenic E. coli (DEC) and extraintestinal pathogenic E. coli (ExPEC), cause numerous human infections annually. Retail meats are generally contaminated with E. coliand may serve as a vehicle transmitting pathogenic E. coli. The objectives of this project were to detect and characterize different pathogenic E. coli from retail meats, and to explore their potential in causing human infections. E. coli isolates recovered from ground beef, ground turkey, chicken breast and pork chop during 2002 to 2007 were screened for Shiga toxin genes and Shiga toxin-producing E. coli (STEC) were characterized phenotypically and genotypically. In addition, E. coli isolates recovered in 2006 were also examined for virulence genes specific for other DEC. The results demonstrated that retail meats, especially ground beef, were contaminated with diverse STEC strains and some strains contained Shiga toxin genes associated with severe human infections. The presence of atypical enteropathogenic E. coli in retail meat is also of concern due to their potential to cause human infections. Meanwhile, E. coli isolates recovered in 2006 were investigated for the presence of five ExPEC-defining virulence genes using multiplex PCR. Identified ExPEC isolates were characterized by serotyping and phylogenetic grouping, and their antimicrobial susceptibility data were analyzed. The findings showed that ExPEC, including antimicrobial resistant strains, were widely distributed in retail meats, especially in chicken and turkey products. This indicates that meat may be a vehicle for dissemination of ExPEC strains. ExPEC strains identified were further examined by multiplex PCR for the presence of 21 uropathogenic E. coli (UPEC) virulence genes. Selected strains were further characterized by multi-locus sequence typing and studied for their interactions with human bladder epithelial cells. Data showed that most UPEC virulence genes selected could be detected in isolates from meat. And some isolates belonged to sequence types associated with clinical UPEC. Meat-source isolates exhibited lower level of adherence and invasion compared to a clinical UPEC strain. These observations suggested that a small proportion of E. coli isolates from retail meats resemble human UPEC in various aspects, but their potential in causing human UTI needs further investigation.Item Isolation and characterization of antimicrobial resistant Staphylococcus aureus in retail ground meats(2010) Li, Yi; Meng, Jianghong; Food Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Staphylococcus aureus is commonly present in humans and animals. It can cause a variety of suppurative infections, food intoxication and toxic shock syndrome. Antimicrobial resistant S. aureus, especially methicillin-resistant S. aureus (MRSA), have emerged and are a major public health concern. There is an increasing risk of food production animals serving as a reservoir and transmitting S. aureus and MRSA in community environments. Due to the increased food safety risk posed by MRSA in addition to its multidrug resistance, we were interested in determining the prevalence of S. aureus and MRSA in retail meat and investing the multidrug resistance of the S. aureus isolates. A survey study was conducted, involving 480 retail ground meat samples (231 ground pork and 249 ground beef) collected in the Washington DC area from March 2009 to March 2010. Approximately 42.08% (n = 202) of the samples were identified as S. aureus positive and one MRSA isolate was recovered from a ground beef sample. Antimicrobial resistance testing showed 53.34% of recovered S. aureus isolates exhibited different levels of antimicrobial resistance to CLI, CHL, GEN, LEVO, CIP, SYN and TGC. The MRSA isolate was resistant to 8 of 22 antimicrobials tested. PFGE fingerprinting identified the MRSA isolate as USA300 subtype, which also carried genes of virulence factors PVL and protein A. Our findings indicated that antimicrobial resistant S. aureus strains were common in retail ground beef and port, and that MRSA could also be present in such products that could potentially serve as a reservoir.Item Blue Crab Farming on Maryland's Eastern Shore(2009) Donnelly, Justin Michael; Ambrose, Michael A; Architecture; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Biologists speculate that a combination of pollution and overharvesting might soon lead to the extinction of the blue crab in the Chesapeake Bay. This project investigates inland crab farming as a means by which to resurrect the region's dwindling blue crab industry and alleviate pressure on rapidly declining wild fisheries. Although the project transplants the blue crab onto land, it minimizes the impact to the plants and animals displaced. In short, the project asks us to rethink how we fish and how we farm and how they relate. The architectural proposal seeks to establish the general parameters of a heretofore untried blue crab farming operation and to apply these rules to a specific farm project in Dorchester County, Maryland. The final product consists of a series of greenhoused raceways, constructed wetlands, working meadows, a laboratory for rearing crab eggs to juvenile development, a picking/processing facility, restaurant, and modest educational facilities.Item Feasibility of Soluble Leaf Proteins as a Carrier for Vitamin D(2009) Cherian, Ansu Elizabeth; Lo, Y. Martin; Food Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Resurgence of vitamin D deficiencies in recent years has ascribed the need for expansion of fortification strategies in food. Alluding to the fat soluble and sensitive chemical nature of vitamin D, existing fortification strategies invariably require using a substantial amount of fat as carriers for vitamin D. Though milk proteins have demonstrated good binding properties with vitamin D; allergen issues, lactose intolerance, and the need to cater to vegan population deter its extensive use. In this study, soluble leaf proteins extracted from low-alkaloid tobacco leaves were investigated as a possible carrier. Crude tobacco leaf proteins were extracted by a high-throughput mechanistic process, followed by a freeze-drying process to encapsulate vitamin D. Up to 84.68% (w/w) of vitamin D was successfully retained by tobacco leaf proteins using the process developed, indicating that crude leaf protein recovered from tobacco could be employed as an effective carrier for vitamin D.Item CHARACTERIZATION OF ALGAL BIOMEAL FOR APPLICATIONS IN FOOD(2009) Sanghvi, Avani Mukesh; Lo, Martin; Food Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Conventionally used as animal feeds, microalgae are now cultivated for products such as omega-3 fatty acids, resulting in a high amount of biomass as by-product. The biomass obtained after the extraction of DHA from Crypthecodinium cohnii is called `algal biomeal'. Being nutritionally rich, the biomeal has potential to be used as a value-added ingredient in human food and animal feeds. Evaluation of the biomeal properties resulted in the development of a water-based sauce formulation which was analyzed for its proximate composition, textural attributes and microbial stability. The sauce was rich in carbohydrate and protein with low fat and ash content. It was microbiologically and texturally stable under refrigeration. This research shows that development of a shelf-stable palatability enhancer using algal biomeal offers a new ingredient for the food and feed industries, whereas the ability to produce a value-added ingredient also offers a viable option for algal biomeal.Item Antioxidant and Anti-proliferative properties of selected grape seed extracts(2009) Bloom, Raquel Zorah; Yu, Liangli; Nutrition; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This study examined chardonnay, muscadine, concord, and ruby red grape seed oil and flour extracts for antioxidant and anti-proliferative properties. The extracts were tested for total phenolic content, DPPH* · and ABTS*+ ·radical scavenging capacity and effect against HT-29 cancer cell proliferation. All of the grape seed extracts exhibited ABTS*+ · and DPPH*· radical quenching activity. The flour extracts from chardonnay demonstrated the highest ABTS*+· radical quenching capacity of 186 μμmoles trolox equivalents/g and DPPH* · radical quenching activity of 30 μμmoles trolox equivalents/g. All of the grape seed oil and flour extracts contained significant levels of phenolics. Chardonnay grape seed flour extract displayed the most prominent dose dependent anti-proliferative effect. Muscadine and ruby red, but not concord grape seed flour extracts, also exhibited anti-proliferative activities. The collected data advocate for the potential of grape seed extracts as dietary sources of anti-proliferative and antioxidant components.Item Nutraceutical Properties of Low alpha-Linolenic Soybeans Grown in Maryland(2009) Whent, Monica; Yu, Liangli; Food Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Eight soybean genotypes grown in Maryland were analyzed for total phenolic content (TPC), antioxidant capacity, isoflavone composition, lutein content, tocopherol composition, and fatty acid profile. The soybean samples consisted of seven low alpha-linolenic (18:3n-3) experimental lines and one standard cultivar for comparison. 18:3n-3 levels were negatively correlated with oleic acid (18:1n-9). The isoflavones daidzein and genistein were positively correlated with 18:3n-3 levels. Alpha-tocopherol, gamma-tocopherol, and total tocopherols were negatively correlated with 18:3n-3. Two of the reduced 18:3n-3 lines contained significantly higher lutein levels than the ordinary cultivar. All low alpha-linolenic lines contained similar antioxidant capacity to the non-modified genotype. The results of this study show that the Maryland-grown low 18:3n-3 soybeans are sources of antioxidants and isoflavones and may be consumed for health benefits. Specific genotypes may be selected for food production to obtain the most desirable combination of nutritional, nutraceutical, and chemical properties.