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Type II diabetes mellitus (T2DM) is a chronic disease that has a worldwide prevalence which is expected to rise dramatically over the course of the next thirty years. The disease has reached pandemic stages of development in many cultures, most notably in developing countries, followed somewhat closely by developed countries with access to an overabundance of refined carbohydrates and fat (refined oils). T2DM is a condition that can be prevented or managed, but not cured; therefore a method of stymieing the development of this disease is paramount to halting its progressively increasing morbidity. In this study, bartlett pear and kiowa blackberry were investigated in relation to their ability to modify and improve both glucose metabolism and hypertension management with in vitro assay models. Effectiveness and bioactive functionality was evaluated by various in vitro assays to study the properties of: 100% bartlett pear juice, 100% kiowa blackberry juice and a ratio of 70:30 pear: blackberry juice found to have increased phenolic properties due to synergy in previous studies. These assays aimed at determining: alpha-amylase and alpha-glucosidase inhibition, angiotensin converting enzyme inhibition, total soluble phenolic content and antioxidant capabilities. These juices were also fermented with Lactobacillus helveticus and Bifidobacterium longum, common yogurt culture strains, to investigate if fermentation would improve the bioactive functionality of pear: blackberry synergies. A secondary goal of the experiment was to investigate if these fruit juices could prevent the growth of Helicobacter pylori, which is a common bacterium found in the stomach which can lead to cancer.

The objective of this thesis is to develop a method by which antimicrobials are delivered into a food product as a concentrated dose to the specific area in which the microorganism is growing without interference from the food matrix. More specifically, we plan to achieve this by delivering the antimicrobials nisin and lysozyme attached to nanoparticles and emulsion droplets. We hypothesize that (a) the attachment to a delivery vessel may increase the local concentration of the antimicrobial in the vicinity of the bacterial pathogens and (b) that the size and charge of the nanoparticle following attachment of the antimicrobials will be critical to its efficacy against pathogens. This thesis is designed to test this hypothesis using silver nanoparticles with well defined sizes and surface chemistry that allow control over the loading of the particle and oil droplets to which nisin is a secondary layer attached to pork gelatin which acts as the primary emulsifier.

Type 2 diabetes is a worldwide and costly disease that requires complex cellular metabolic breakdown for its development. The onset of this disease is indicated by an abnormal elevated blood glucose level (hyperglycemia) and coexistence with hypertension. Apple and blueberry are the two popular fruits in the U.S. that are high in bioactive phenolic compounds. The objectives of this thesis were to investigate the synergistic health benefits of apple cider and blueberry juice for potential management of early stages of type 2 diabetes using in vitro enzyme assay models and enhance their synergistic effects through fermentation using probiotic strains of lactic acid bacteria. Apple cider and whole blueberry juice were combined at 5 different ratios. Synergistic interaction of the phenolic bioactives between the two juice sources was observed in all assays. For maintenance of high α-glucosidase, α-amylase and ACE inhibition activities, a proportion of 80% apple cider and 20% whole blueberry juice was selected as the optimum combination reflecting maximum health benefits to potentially manage hyperglycemia and hypertension associated with type 2 diabetes. The 80/20 apple cider and blueberry juice combination was fermented at 24 and 48 h using Lactobacillus helveticus R0052 and Bifidobacterium longum isolate. High inhibition of α-glucosidase, α-amylase and ACE enzymes was observed in apple cider/blueberry juice combination. Strong antimicrobial activity against H. pylori was exerted by L. helveticus- and B. longum-fermented sample at 48 h. A possible mode of action through the synergy between lactic acid and proline oxidation pathway was suggested.

Commercial production of catfish is the leading aquaculture industry in the United States. Production in Mississippi, Louisiana, Alabama, and Arkansas representing 96% of the total catfish sales in the USA. In 2017, the USDA-FSIS added testing of generic Escherichia coli and Enterococcus to the sampling of Siluriformes. The incidence of Escherichia coli in fish and seafood has been associated with possible fecal matter contamination. However, this indicator bacteria could also be a part of the natural microflora of catfish ponds where processing plants collect hybrid catfish. Aerobes, Psychrotrophs, Coliforms, Escherichia coli, and Enterobacteriaceae counts among environmental, liquid and fish samples were tested every season and periodically during one day of operation. Generic Escherichia coli counts were greater in late Summer (P ≤ 0.05) for liquid samples (1 log CFU/g) . During the day, Escherichia coli appeared to be more recurrent in the afternoon at the skinning step (P ≤ 0.05).

Flavonoids are secondary metabolites that have significant roles in plant defense and human nutrition. Glucosyltransferases (GTs) transfer sugars from high energy sugar donors to other substrates. Several different kinds of flavonoid GTs exist in the tissues of grapefruit making it a model plant for studying their structure and function. The goal of this investigation is to determine the expression patterns of 7 putative secondary product GTs during grapefruit growth and development by quantifying mRNA expression levels in the roots, stems, leaves, and flowers. This research was designed to test the hypothesis that these 7 GT's are expressed constitutively. Alternatively, one or more could be expressed in a tissue-specific manner and/or developmentally regulated. Six growth stages were defined. Findings show that there were variable degrees of PGT expression. Therefore, results were more consistent with the alternative hypothesis that putative secondary product GT expression was tissue specific and/or developmentally regulated.

Cholesterol is a fat-like molecule found among lipids in animal (including human) tissues. It is needed for maintaining good health. However, health issues have been raised because of the strong correlation between high levels of cholesterol in the body and cardiovascular disease. An HPLC method for quantitative determination of cholesterol in foods is presented. This involves a C-18 stationary phase using a 70:30 methanol: 2-propanol mobile phase with an UV detector set at 212 nm. The method showed linearity in the range 5.0 to 100.0 μg/mL and also good reproducibility with relative standard deviation of 4.22%, 2.71%, 4.8%, and 3.7% for the different samples analyzed. The mean recovery of the butter sample was 106.5%. The samples under investigation were common food items such as butter, lard, and two different types of cheese.

The Food Safety Modernization Act (FSMA) has a regulation stating that there can be no detectable generic Escherichia coli in agricultural water. The objective of this study was to optimize the use of peracetic acid (PAA) as a mitigating strategy in postharvest processing. This project began by investigating the impact of storage temperatures on stability of a commercially available PAA sanitizer. Regression analysis showed a quadratic relationship in the concentration of PAA over 12 weeks when storing the product at 4, 20 and 37°C. Stability of the product was also investigated in the presence of organic load over time at 60ppm PAA. PAA significantly decreased at an organic load level of 750COD. From this, the impact of various ratios of hydrogen peroxide (H2O2) and PAA were investigated further to see the efficacy against E. coli O157:H7 over three hours with reinoculation of bacteria after 3 hours. A higher level of PAA in the solution had a greater inactivation efficacy against E. coli O157:H7. The impact of concentration, organic load, temperature and pH on the efficacy against E. coli O157:H7 and stability of PAA over four hours was then investigated. All of the conditions tested showed a significant decrease in H2O2 and PAA concentrations over time, except at concentration of 80ppm, with varying rates of depletion under each condition tested. This study will help to create guidance on optimizing the use of PAA. With this knowledge growers can understand how changes in their post-harvest processing water can affect sanitizer performance.

This study focused on evaluating the antimicrobial activity of chlorine dioxide (ClO2) and different plant-based antimicrobials (carvacrol, thymol, and eugenol as bioactive compounds and muscadine extract- ME and blueberry extract- BBE as plant extracts) against selected foodborne pathogens under in vitro conditions and on produce (spinach and blueberries). In addition, bacterial microbiota associated with blueberries and blueberry farm environments from three different regions: Cundinamarca, Colombia; Mississippi, United States; and Guadalajara, Mexico, was determined. Under in vitro conditions, carvacrol and thymol were more effective (lower MICs and MBCs) than eugenol against Salmonella spp., Escherichia coli O157:H7 (MIC=MBC=0.2 mg/ml), and Listeria monocytogenes (MIC=MBC=0.4 mg/ml). Both plant extracts had the same MIC and MBC for Salmonella spp. while BBE had stronger bactericidal effect on Escherichia coli O157:H7 (MBC=150 mg/ml) and ME on L. monocytogenes (MBC=100 mg/ml). ClO2 had stronger bacteriostatic effect on L. monocytogenes (MIC=1 ppm) than on the Gram-negative bacteria (MIC=3 ppm). For the produce study, 300 mg/ml ME exerted the highest (P ≤ 0.05) E. coli O157:H7 reduction (4.5 log CFU/g at day 1) on spinach, and 3 ppm ClO2 + 300 mg/ml ME had the highest (P ≤ 0.05) L. monocytogenes reduction on both (4.5-5.6 log CFU/g). There was a similar (P>0.05) E. coli O157:H7 reduction on blueberries, regardless of antimicrobial treatment. For the microbiota study, Proteobacteria was the most abundant phylum in blueberries, soil, and water, with the exception of fruits from Mexico. Blueberries grown on the different regions shared two predominant genera: Heliorestis (10.5-47.4%) and Thiomonas (5.0-9.1%). Nonetheless, alpha and beta diversity revealed that blueberry microbiota structures were distinctive. PCoA plots revealed that within regions the microbial composition distribution was different (P ≤0.05) among fruits, soil, and water. Based on the results, ME combined with ClO2, could represent an antimicrobial alternative against foodborne pathogens for the produce industry. Furthermore, the study of the microbiota provided a good understanding on the bacterial community profile in blueberries and the blueberry farming environment across regions.

Microbubbles are small gas-filled bubbles with diameters ranging from 50 to 1 μm, and less than 200 nm are called nanobubbles. Their small sizes and large specific surface area result in a high gas dissolution rate and long lifetime in liquid. Ozone is a strong oxidant that destroys microorganisms and only produces oxygen as the final by-product in fresh water. However, due to the poor stability of aqueous ozone, critical gas waste happens during treatments which leads to a high economic loss. Microbubbles have shown promising enhancement of ozone treatment. In previous studies, ozone microbubbles exhibited excellent efficacy in the removal of organic contaminants and inactivation of microorganisms including bacteria, spores, and fungi, but few articles discuss the virus inactivation of ozone microbubbles treatment. Human noroviruses (NoVs) are the primary cause of foodborne illnesses in the US, and the development of effective inactivation methods is crucial. Because of the absence of suitable in vitro cultivation methods for NoVs and the constraints of the available infectivity models for these viruses, most of the studies about inactivation use surrogate viruses that are similar to NoVs in genetics and structure. Tulane virus is a NoV surrogate that can identify the same putative co-factor. This study focuses on the influence of treatment time, disinfectant air exposure, and the presence of organic contaminants on the inactivation efficacy of ozone microbubbles or millimeter bubbles. The results demonstrate that more than one log10 reduction was produced when the Tulane virus was exposed to ozone millimeter bubbles and ozone microbubbles for a short period of time, even in the presence of high organic load (FBS), and the protective effect of the organic load was shown when the disinfectant induced volume increased. The findings indicate that conducting further research on ozone microbubbles in aqueous applications in food-related applications is useful.