Life Sciences Commons^™

Evaluation Of A Natural Antimicrobial-Based Sanitizer As An Alternative To Chlorine For Reducing Foodborne Pathogenic Bacteria On Organic Produce, Ellen Rebecca Simmons

Masters Theses

There is a need for the development of a “natural” sanitizing agent to reduce or eliminate foodborne pathogens that meets USDA organic standards, as an alternative to chlorine. The sanitizer needs to eliminate foodborne pathogens and prevent cross contamination in rinse liquids in the presence of organic matter. In this study, the focus was to evaluate a natural antimicrobial-based sanitizing (NABS) agent in rinse liquids to determine if it was capable of eliminating foodborne pathogens on organic produce through cross-contamination studies. Five-serovar/strain cocktails of pathogenic bacteria were combined to form an inoculum cocktail, which was used to inoculate the produce. …

Chemical Disinfectants For The Inactivation Of The Emerging Foodborne Aichi Virus, Andres Ignacio Arreaza

Masters Theses

Aichi virus (AiV) is an emerging virus responsible for gastroenteritis outbreaks worldwide. Improved decontamination methods are being researched to control AiV spread. The effects of common hard surface disinfectants including benzalkonium chloride (BAC), potassium peroxymonosulfate (KPMS), tribasic sodium phosphate (TSP) as well as sodium metasilicate (SMS) and calcium hypochlorite (Ca(ClO)₂) [calcium hypochlorite] against AiV need to be explored. The objective of this research was to determine their effects against AiV using suspension and carrier tests over various contact times at room temperature. Phosphate buffered saline (pH 7.2 as control), 0.64% BAC, 10% KPMS, 10% TSP, 0.16 and 0.3% …

Application Of Bacteriophage Cocktail In Leafy Green Wash Water To Control Salmonella Enterica, Andrea W. Lo

Masters Theses

Produce is responsible for 46% of all foodborne illnesses in the USA. Salmonella enterica causes 19,000 hospitalizations each year, and has been associated with produce. Presently, chlorine based sanitizers are most often used, however organic matter reduces its antimicrobial activity. Bacteriophage treatments are an all-natural, alternative method for pathogen inactivation. The objective of this study was to determine the efficacy of a five-strain bacteriophage treatment against a S. enterica cocktail in simulated wash waters at different temperatures. Bacteriophage and S. enterica were enumerated in simulated wash water solutions. One set of experiments studied bacteriophage and S. enterica growth in TSB+vegetable …

Development Of Nanoemulsion-Based Delivery Systems For Evaluation Of Triglycerides Bioactivity In Caernohabditis Elegans, Jose D. Colmenares

Masters Theses

Digestion and absorption of bioactive free fatty acids have been studied using the nematode Caernohabditis elegans (C. elegans). However, fatty acids mostly occur in foods in the form of triglycerides, which are highly hydrophobic molecules with low water-solubility, thereby making it difficult to study the fate of ingested fatty acids in C. elegans. The purpose of this research was to develop a method to deliver hydrophobic bioactives, including triglycerides, into C. elegans. Nanoemulsions containing triglyceride nanoparticles were prepared by sonication, and nanoparticle ingestion was confirmed by optical and confocal microscopy, and quantified by spectrometry. Changes in fatty …

Evaluation Of The Thermal Inactivation Kinetics Of Surrogate Vegetative Bacteria, Amber Lynne Parham Renix

Masters Theses

Microbial surrogates are defined as non-pathogenic organisms with behavioral and/or survival characteristics correlating to those of specific pathogens. The purpose of this study was to determine the thermal inactivation kinetics (D and z-values) of Lactobacillus bulgaricus ATCC 11842, Lactobacillus fructivorans ATCC 8288, Lactobacillus plantarum ATCC 4008, Listeria innocua ATCC 33091, ATCC 51742, and 11/97, and Staphylococcus carnosus CS-299 as potential surrogates for hepatitis A virus (HAV; D_72°C = 0.9 min). Additionally, the effect of sub-lethal heat on increasing the thermotolerance of L. bulgaricus was investigated. All strains were tested in phosphate buffered saline (PBS) as a …

Gallic Acid-Grafted Chitosan Films As Antioxidant Food Packaging, Ping Guo

Masters Theses

Chitosan is the second most abundant natural polysaccharide in the nature. Due to its biodegradability and film forming ability, chitosan has the potential to be used as an alternative to petroleum-based polymers for food packaging. The presence of a primary amine as well as primary and secondary hydroxyl groups enable chitosan to be chemically modified with various functional groups. Gallic acid (GA) is a natural occurring antioxidant (AOX), which can be grafted to chitosan using by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS). The first project deals with the effect of ethanol (EtOH) concentration on efficiency of grafting GA onto chitosan. …

Development And Evaluation Of Novel Vaccination Strategies For Campylobacter Control In Poultry, Xiang Liu

Masters Theses

Chicken is the primary natural host of Campylobacter, the leading bacterial cause of human enteritis in the US and other developed countries. Thus, mitigation of Campylobacter in chicken using innovative approaches, such as vaccination, will have a significant impact on food safety and public health. Our previous studies have demonstrated that the two outer membrane proteins, CmeC (the essential component of the CmeABC multi-drug efflux pump) and CfrA (a ferric enterobactin receptor), are feasible candidates for immune intervention against Campylobacter. DNA vaccine has appeared to offer various advantages for poultry, particularly when combined with in ovo vaccination. Chitosan-encapsulated …

Spray Fabrication Of Layer-By-Layer Antimicrobial N-Halamine Coatings, Anna Denis-Rohr

Masters Theses

Antimicrobial coatings in which the active agent (e.g. N-halamine) can regenerate activity represent a promising way to prevent microbial cross-contamination. A reported method for applying coatings containing antimicrobial N-halamines is layer-by-layer (LbL) application of polyelectrolytes, which form N-halamines upon cross-linking. Prior reports on dip layer-by-layer (LbL) fabrication have demonstrated the potential of this coating technology; however, spray LbL fabrication would enable more rapid coating and represents a more commercially translatable application technique. In this work, dip and spray LbL methods were used to coat polypropylene (PP) with N-halamine containing bilayers consisting of cross-linked polyethylenimine (PEI) and poly(acrylic acid) (PAA). Further …

The Effect Of Lecithin On Inactivation By Eugenol Of Escherichia Coli O157:H7, Sasha Marie Wilkinson

Masters Theses

Many essential oils and their components are known to have antimicrobial activity. However, their strong aroma, flavor, and hydrophobic nature make them difficult to incorporate into food products. New methods to improve antimicrobial activity at reduced concentrations and/or reduce the influence of food components on antimicrobial activity are needed. In this study, the objective was to combine the emulsifier soy lecithin with eugenol in an attempt to enhance the activity of the latter against the foodborne pathogen Escherichia coli O157:H7.

Eugenol was added to a pH 7.2 sodium phosphate buffer (PBS), PBS with 0.03% (v/v) tryptic soy broth (TSB), PBS …

Effective Education On Consumers' Food Safety Knowledge, Perceptions, And Behaviors At Local Area Farmers' Markets, Molly Louise Albin

Masters Theses

Although extensive research has been conducted to understand consumers’ knowledge of food safety risks, there is a lack of research on consumers’ knowledge, perceptions, and behaviors towards risks associated with locally grown, processed, and manufactured foods sold at farmers’ markets. Recently, there has been a movement toward purchasing local foods to support local economies, out of concern for food miles, or because of a perception of higher quality goods. In Tennessee, the number of farmers’ markets has doubled in five years. Furthermore, previous research determined food safety education is most effective if developed with input from the target audience. The …

Sanitization Effectiveness Of Alkaline-Dissolved Essential Oils As Organic Produce Washing Solutions, Marion Lewis Harness Iii

Masters Theses

Produce is often rinsed immediately post-harvest to remove dirt and debris. Rinse water can be a point of cross-contamination if no antimicrobials are present. While plant essential oils (EOs) are recognized as antimicrobials, their hydrophobicity makes them difficult to implement in rinsing solutions. In this study, the efficacy of emulsified EOs were examined against Salmonella on the surface of cherry tomatoes and Escherichia coli O157:H7 on the surface of baby spinach. Contaminated produce samples were rinsed in an emulsions of clove bud oil or thyme oil at 0.2 and 0.5% (v/v), as well as free chlorine at 200 ppm and …

Preparation And Characterization Of Acid-Induced Gels At Ph 1.0-4.0 And Thermal-Stable Dispersions At Ph 5.5-6.0 Using Preheated Whey Protein, Kangkang Li

Masters Theses

Whey protein (WP) is a good source for producing protein-rich products, including satiety foods and beverages. Thermal aggregation of WP during sterilization or pasteurization impacts food quality important to shelf-stable beverages. Preheating WP improves the thermal stability at neutral acidity, and forming complexes with other molecules to provide charge and/or steric hindrance can be used to improve thermal stability of WP at acidic conditions. Conversely, aggregation properties of preheated WP upon acidification can be used to create unique functional properties. Therefore, studying properties of preheated WP can broaden its application in the food industry.

Gelation of preheated WP and pectin …

Synergistic Interfacial Properties Of Casein And Small Molecule Surfactants For Fabrication Of Essential Oil Nanoemulsions, Dan Su

Masters Theses

Nanoemulsions of essential oils are important for delivery of flavors and antimicrobial preservatives in food systems. The overall goal of this work was to study the formation and properties of essential oil nanoemulsions fabricated with sodium caseinate (NaCas) or its hydrolysates and small molecule surfactants (SMSs). The first group of lemon oil nanoemulsion was prepared with NaCas and Tween 20 using a phase inversion temperature (PIT) method. The combination of NaCas and Tween 20 reduced the turbidity and droplet dimension of emulsions than using them individually. Heating at 90 °C for >1 h resulted in transparent nanoemulsions for samples with …

Eneterotoxigenic Bacillus Cereus And Bacillus Thuringiensis Spores In U.S. Retail Spices, Upasana Hariram

Masters Theses

Bacillus cereus is a ubiquitous organism and a potential foodborne pathogen that can cause two types of gastrointestinal diseases: emesis and diarrhea. The emetic syndrome is caused by a heat and acid stable peptide toxin that is pre-formed in food, while the diarrheal syndrome is associated to two 3-protein, heat labile enterotoxin complexes that are formed in the intestine after ingestion of the organism. There are many reports on the isolation and characterization of Bacillus cereus from various foods, however there are no studies on the levels, toxigenicity and physical characteristics of B. cereus isolated from U.S. retail spices. …