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Full-Text Articles in Life Sciences

Application Of Bacteriophage Cocktail In Leafy Green Wash Water To Control Salmonella Enterica, Andrea W. Lo Nov 2015

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 Nov 2015

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 …


Biotransformation Of Polymethoxyflavones By Gut Microbiome And Molecular Characterization Of Polymethoxyflavones By Surface Enhanced Raman Spectroscopy, Changchu Ma Nov 2015

Biotransformation Of Polymethoxyflavones By Gut Microbiome And Molecular Characterization Of Polymethoxyflavones By Surface Enhanced Raman Spectroscopy, Changchu Ma

Doctoral Dissertations

Polymethoxyflavones (PMFs), a unique class of flavonoids found in citrus fruits has shown beneficial bioactivities. Biological fate of PMFs in the gastrointestinal tract is critical for their bioactivities. PMFs can be biotransformed to produce various metabolites with different bioactivities, and PMFs can also interact with the food matrix, which in turn affects their bioactivities. Therefore, we investigated the biotransformation of two PMFs, namely nobiletin (NBT) and 5-hydroxylnobiletin (5HN) by the gut microbiome. Mice were fed with NBT or 5HN, and small intestinal contents were collected and subjected to anaerobic fermentation by gut microbiome isolated from mice and human volunteers. HPLC …


The Chemopreventive Effect Of Polymethoxyflavones: Targeting The Colorectal Cancer Stem Cells, Fei Xu Nov 2015

The Chemopreventive Effect Of Polymethoxyflavones: Targeting The Colorectal Cancer Stem Cells, Fei Xu

Doctoral Dissertations

Among all the cancers, the death rate of colorectal cancer is one of the highest. Evidence from both murine xenograft model and human trials have shown cancer stem cells (CSCs) are responsible for the initiation, metastasis and recurrence of multiple cancers therefore targeting colorectal CSCs would be a promising chemo-preventive/ therapeutic strategy. Polymethoxyflavones including nobiletin (NBT) and 5-demethylatednobiletin (5DN) are exclusively found in citrus peels and have been shown to have anti-cancer effects. Our previous studies in the biotransformation and tissue distribution of NBT and 5DN have shown that in order to fuller evaluate the biological impact of those two …


Fabrication, Characterization And Biological Fate Of Phytochemical Delivery System, Jingjing Chen Nov 2015

Fabrication, Characterization And Biological Fate Of Phytochemical Delivery System, Jingjing Chen

Doctoral Dissertations

Polymethoxyflvones (PMFs) are a group compounds with promising cancer preventing activities and many other health benefits. There's a growing interest in fabricating delivery systems for PMFs as well as other phytochemicals due to their low water solubility. Firstly, we use nanoemulsion delivery system to encapsulate β-carotene. Sonication assisted method was developed to dissolve β-carotene to ensure minimum degradation. Powdered nanoemulsion was obtained after spray dry and freeze dry. Sample obtained after freeze dry showed better physiochemical characteristics. Then we use protein nanoparticle delivery system to encapsulate PMFS. The nanoparticle delivery system was fabricated by mixing the aqueous phase …


Pro- And Antioxidant Effects Of Phospholipids On Lipid Oxidation In Bulk Oil, Leqi Cui Nov 2015

Pro- And Antioxidant Effects Of Phospholipids On Lipid Oxidation In Bulk Oil, Leqi Cui

Doctoral Dissertations

The aim of this thesis is to explore how phospholipids at concentrations similar as in refined vegetable oils impact bulk oil lipid oxidation. The possible formation of association colloids and synergism with primary antioxidants are considered. The results provided a better understanding of the pro- and antioxidant activities of phospholipids. Lipid oxidation leads to quality deterioration by generating off-flavor, nutrient loss, color alteration, texture changes, and even generation of potential toxic products. Phospholipids are important minor components in edible oil that play a role in lipid oxidation. Surface active phospholipids have an intermediate hydrophilic–lipophilic balance value, which allows them to …


Role Of Lipid-Based Delivery Systems In The Biological Fate Of Lipophilic Nutraceuticals And Inorganic Nano-Particles In The Gastrointestinal Tract, Mingfei Yao Nov 2015

Role Of Lipid-Based Delivery Systems In The Biological Fate Of Lipophilic Nutraceuticals And Inorganic Nano-Particles In The Gastrointestinal Tract, Mingfei Yao

Doctoral Dissertations

The oral bioavailability of lipophilic bioactive molecules can be greatly increased by encapsulating them within engineered lipid nanoparticles, such as micelles, microemulsions and nanoemulsions. After ingestion these engineered lipid nanoparticles are disassembled in the gastrointestinal tract (GIT), and then reassembled into biological lipid nanoparticles (mixed micelles) in the small intestine. These mixed micelles solubilize and transport lipophilic bioactive components to the epithelium cells. The mixed micelles themselves are then disassembled and reassembled into yet another form of biological lipid nanoparticle (chylomicrons, CMs) within the enterocyte cells. The CMs carry the bioactive components into the systemic (blood) circulation via the lymphatic …


Effects Of Conjugated Linoleic Acid (Cla) On Skeletal Muscle Metabolism, Yoo Kim Nov 2015

Effects Of Conjugated Linoleic Acid (Cla) On Skeletal Muscle Metabolism, Yoo Kim

Doctoral Dissertations

Although it is well known that increased physical activity can help reduce incidences of obesity, physical activity can be influenced by complex issues, making it difficult to use universal means to control obesity. Recent discoveries of the effects of exercise at the cellular level opened up the unique opportunity to develop compounds with ‘exercise-like’ effects. In fact, CLA has been shown to promote voluntary activity and endurance capacity in mice. Thus, the purpose of these studies is to determine the mechanisms of conjugated linoleic acid on muscle metabolism via the modulation of biochemical events including mitochondrial biogenesis and the alternation …


Structural Design Approaches For Creation Of Reduced Fat Products, Bicheng Wu Nov 2015

Structural Design Approaches For Creation Of Reduced Fat Products, Bicheng Wu

Doctoral Dissertations

In awake of the health issues related with high-calorie diet, there was a strong focus in the development of reduced-fat products in the food industry. However, fat plays an important role in determining the quality attributes of food products such as texture, appearance, flavor and stability, therefore there has been limited success for reduced-fat products. This thesis project thus targeted liquid and semi-solid products such as dressings, sauces, and aimed to address problems associated with low-fat by utilizing structural designed approach. The first part of this project focused on using controlled aggregation of protein-stabilized lipid droplets to regulate the microstructure …


Physicochemical And Toxicological Assessment Of Antimicrobial Ε-Polylysine-Pectin Complexes, Cynthia L. Lopez Pena Aug 2015

Physicochemical And Toxicological Assessment Of Antimicrobial Ε-Polylysine-Pectin Complexes, Cynthia L. Lopez Pena

Doctoral Dissertations

ε-Polylysine is an appealing FDA-approved, all natural antimicrobial biopolymer effective against a wide range of microorganisms. Its implementation is greatly limited by its strong cationic charge, which has been linked to instability in food systems, perceived astringency and bitterness, and the ability to inhibit lipid digestion. Previous studies have shown that controlled complexation of ε-polylysine with anionic pectin is able to prevent instability and astringency in simplified model food systems, while maintaining the antimicrobial character of polylysine. Isothermal titration calorimetry, micro-electrophoresis, microscopy, and turbidity analyses of the stability of electrostatic pectin-polylysine complexes in the presence of strongly anionic κ-carrageenan, and …


Spray Fabrication Of Layer-By-Layer Antimicrobial N-Halamine Coatings, Anna Denis-Rohr Jul 2015

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 …


Eneterotoxigenic Bacillus Cereus And Bacillus Thuringiensis Spores In U.S. Retail Spices, Upasana Hariram Mar 2015

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. …


Rationalizing Nanoemulsion Formation For Encapsulation, Protection And Delivery Of Bioactive Food Components, Ying Yang Mar 2015

Rationalizing Nanoemulsion Formation For Encapsulation, Protection And Delivery Of Bioactive Food Components, Ying Yang

Doctoral Dissertations

The objective of this thesis was to design and develop novel food-grade nanoemulsion-based delivery systems for the encapsulation, protection and delivery of lipophilic bioactive food components. These delivery systems could be widely applied in aqueous-based fortified food products, such as beverages, salad dressing and yogurt etc. Both the low- and high-energy methods could be used for fabricating nanoemulsions (r < 100 nm). The microfluidization method could form nanoemulsions at low surfactant-to-oil ratios (SOR < 0.1), but it required the use of high-energy inputs and expensive equipment. On the other hand, the spontaneous emulsification method could also form ultrafine emulsions and moreover it was simple and inexpensive, but it required much higher surfactant-to-oil ratios (SOR > 0.5) for forming nanoemulsions. Q-Naturale® is a natural food-grade surfactant, which is got from the bark of the Quillaja saponaria Molina tree. By using high pressure homogenization (microfluidization), Q-Naturale® could form relatively small droplets (d < 200 nm) at low surfactant-to-oil ratios (SOR < 0.1), but the droplets were not as small as those produced using Tween 80 under similar conditions (d < 150 nm). The emulsions formed by using Q-Naturale® …


Experimental And Modeling Studies On The Formulation Of Stable Lipid Nanoparticle Dispersions, Yihui Yang Mar 2015

Experimental And Modeling Studies On The Formulation Of Stable Lipid Nanoparticle Dispersions, Yihui Yang

Doctoral Dissertations

This thesis presents both experimental and modeling studies on the formulation of stable lipid nanoparticle dispersions. A population balance equation (PBE) model was developed for prediction of the average polymorph content and aggregate size distribution to better understand the undesirable SLN aggregation behavior. Experimental and modeling studies showed that the polymorphic transformation was the rate determining step for my system, SLNs with smaller initial size distributions aggregated more rapidly, and aggregates contained particles with both alpha and beta crystals. Next the effect of different liquid carrier oils on the crystallization and aggregation behavior of tristearin NLC dispersions was investigated. I …


Prediction Of Emulsion Drop Size Distributions With Population Balance Equation Models To Enable Emulsified Product Design, Shashank Maindarkar Mar 2015

Prediction Of Emulsion Drop Size Distributions With Population Balance Equation Models To Enable Emulsified Product Design, Shashank Maindarkar

Doctoral Dissertations

Oil-in-water emulsions are ubiquitous dispersed phase systems with diverse applications in consumer products, processed foods, and the pharmaceutical industry. Emulsion formulation variables and process operating conditions both impact the drop size distribution, a key property that influences emulsion rheology, stability, texture, and appearance. A typical emulsified product requires the drop size distribution to be maintained within acceptable limits. Due to a lack of quantitative understanding, emulsified products are currently manufactured by combining a broad knowledge of previous product formulations with empirical scientific experimentation. An alternative to trial-and-error experimentation is to utilize a suitable mathematical model to predict the drop size …


Layer-By-Layer Antimicrobial N-Halamine Polymer Coatings For Food Contact Materials, Luis J. Bastarrachea Gutierrez Mar 2015

Layer-By-Layer Antimicrobial N-Halamine Polymer Coatings For Food Contact Materials, Luis J. Bastarrachea Gutierrez

Doctoral Dissertations

Cross contamination during food processing represents a risk for public health and financial burden. Surface modification of food contact materials to render them antimicrobial can be effective against such risk. The objective of the present work was to develop antimicrobial coatings with the potential to be applied in a variety of food contact materials. The polymer coatings developed became antimicrobial by incorporation of a type of chlorinated compounds called N-halamines, capable of regenerating their antimicrobial activity. Two layer-by-layer (LbL) assembly surface modification procedures were followed. In the first procedure, bilayers of branched polyethyleneimine (PEI) and poly(acrylic acid) (PAA) were applied …