Food Microbiology Commons^™

Bifidobacterial Metabolism Of Fucosylated Human Milk Oligosaccharides Influences Structure And Function Of The Infant Gut Microbiome

Doctoral Dissertations

Human milk contains human milk oligosaccharides (HMOs) that are indigestible and pass intact through the infant gastrointestinal tract where they are available for microbial metabolism. HMOs incorporate the same monosaccharide building blocks but vary structurally in primary sequence of monomeric components. Primary sequences are further diversified by degree of polymerization, branching, and secondary modifications such as fucosylation. Fucosylated HMOs (fHMOs) are highly abundant and can account for over 30% of total HMOs. Infant-colonizing Bifidobacterium longum subsp. infantis (B. infantis) possesses a specialized gene cluster conveying the ability to metabolize fHMOs. This study presents an in-depth analysis of B. …

Seasonal Trends And Sampling Time Of Day On Overall Microbial Population And Indicator Organisms In Catfish Parts And Catfish Processing Environment, Maria Gabriela Hidalgo-Sindoni

Theses and Dissertations

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 …

Microstructure And Sensory Attributes Of Rabbiteye Blueberries Subject To Osmotic Dehydration And Two Freezing Methods, Antonio Carlos Garcia

Theses and Dissertations

Frozen, thawed and osmotically-dehydrated highbush (HB) (Vaccinium corymbosum) and rabbiteye (RB) (V. virgatum) blueberries were analyzed under a scanning electron microscope (SEM) to observe microstructural differences in their skin. Rabbiteye blueberries of both frozen, thawed and osmotically-dehydrated treatments, had thicker skins than highbush blueberries. Rabbiteye blueberries, collected from local farms, packed and blast frozen (PBF), had thinner skins than individually quick-frozen (IQF) blueberries. Washing berries prior to freezing had no effect on skin thickness. Sensory analysis of samples determined there were no differences (p > 0.05) between PBF and IQF methods and species with respect to skin intactness, grittiness, sweetness, and …

Antimicrobial Efficacy Of A Citric Acid/Hydrochloric Acid Blend, Peroxyacetic Acid, And Sulfuric Acid Against Salmonella On Inoculated Non-Conventional Raw Chicken Products, Emma Nakimera

Dissertations, Theses, & Student Research in Food Science and Technology

The utilization of non-conventional chicken parts as human food varies widely across countries. The high prevalence of Salmonella, especially in the giblets, poses a high risk to public health. Poultry processors have implemented multiple hurdle technology to reduce this gram-negative pathogen in chicken parts. This study was conducted to evaluate the antimicrobial efficacy of a commercial blend of citric acid/ hydrochloric acid (CP), peroxyacetic acid (PAA), and sulfuric acid (SA) in reducing Salmonella inoculated on two chicken giblets: livers and hearts. Chicken hearts and livers were inoculated (6 log CFU/ml of rinsate) by individually immersing them in a cocktail …

Evaluating The Efficacy Of Germination And Fermentation In Producing Biologically Active Peptides From Pulses, Ashley Newton

Dissertations, Theses, & Student Research in Food Science and Technology

Recently, there has been a profound increase in demand of plant-based proteins, especially pulse proteins. However, pulses contain high concentrations of antinutritional factors that hinder the digestibility of proteins. Processing techniques such as enzymatic hydrolysis, microbial fermentation, and physical processing modulate nutritional quality and functionality of pulses. Processing also releases peptides from parent proteins that exhibit health-beneficial bioactivity against various disease risk factors. In this study, germination, gastrointestinal digestion, and microbial fermentation were evaluated to determine the nutritional quality and release of bioactive peptides during and after processing.

Germination of chickpeas (Cicer arietinum L.) modulated the protein profile, and …

The Invisible Meat Microcosmos - Investigations Of Processed Meats' Specific Spoilage Organisms, Rebecca Furbeck

Theses and Dissertations in Animal Science

As humankind grows in population, so will our need to compete against bacterial populations which spoil foodstuffs before we are able to consume them. This dissertation aims to identify the bacterial communities responsible for meat spoilage, and the mechanisms that govern the behaviors of these organisms. The literature review summarizes the state of knowledge regarding factors that influence meat microbiome composition, and how analytical methods can influence research outcomes. Study 1 aimed to identify the impact of additional ingredients and processing steps on the microbial ecology of processed turkey products. The main specific spoilage organisms (SSOs) belonged to the orders …

Thermal Inactivation Kinetics Of Salmonella In Milk Powder As Impacted By Water Activity And Powder Type, Erika Litta Kadas

Graduate Theses and Dissertations

Historically, low-water activity (aw) foods (aw <0.65) were considered to be microbiologically safe for consumption. However, these foods have been implicated in outbreaks of pathogens such as Salmonella enterica, at a frequency that surely challenges this assumption of safety. Although usually implicated in outbreaks involving poultry and egg products, Salmonella spp. have frequently been the culprit in several outbreaks and recalls associated with low-water activity foods (LWAF) due to contamination resulting from the environment, animals, or even the employees during pre-or post-processing. One such LWAF that has been associated with Salmonella spp. outbreaks is milk powder. Milk powders are used in a variety of products ranging from infant formula to confectionary goods. With their widespread use, improving their safety is imperative. A key step in improving their safety is to thoroughly investigate preventive controls related to milk powder processing. The Food Safety Modernization Act (FSMA) established the Preventive Controls for Human Foods Rule, which mandates that processors design and establish a food safety plan outlining any potential hazards and the steps they will take to ensure those hazards do not compromise the safety of the product. Presently, the dairy industry does not have an established kill-step for milk powders post-spray drying. Spray drying may reduce some microbial populations, however, desiccation(e.g., spray drying) is not considered a kill-step. The work outlined in this thesis aims to assist our dairy industry partners in establishing their own thermal process for milk powders post-spray drying. Moisture sorption isotherms of two milk powders (nonfat dry milk: NFDM and a milk protein concentrate with 85% protein content: MPC-85) were determined and showcased that the temperatures at which the isotherms were determined (23, 40, or 60°C) significantly affected both the adsorption and desorption isotherms (p<0.0001) for each powder. Secondly, the thermal inactivation kinetics of Salmonella spp. in both powders were evaluated at two different water activities (0.20 and 0.30) and three temperatures (75, 80, and 85°C) to determine the effect of water activity on the thermal resistance of a cocktail of Salmonella spp. The D-values of Salmonella were heavily influenced by the thermal treatment temperature (p< 0.0001), but not the water activity (p >0.05). The overall findings contained within this thesis provide valuable information about the thermal inactivation kinetics of Salmonella spp. to our partners in the dairy industry so that they may implement an appropriate thermal process for their milk powders.

Identification Of Gut Microbiome Composition Responsible For Gas Production, Erasme Mutuyemungu

Dissertations, Theses, & Student Research in Food Science and Technology

Gas production remains a significant barrier to increasing intake of dietary fiber-containing foods for many consumers. Therefore, this thesis is comprised of two studies focusing on the role of the gut microbiome in contributing to gas production during fermentation of dietary components. Previous studies have reported significant correlations between Megasphaera elsdenii and gas production during fermentation of pulses. Therefore, the objective of the first study was to determine the role of M. elsdenii in gas production by the microbiome during fermentation of foods commonly associated with gas production. Human fecal microbiomes were separated based on the presence (Me+) or absence …

Safety Assessment Of Novel Foods And Food Proteins, Niloofar Moghadam Maragheh

Dissertations, Theses, & Student Research in Food Science and Technology

The global food market needs to grow and supply food demand to feed the growing world population. Alternative food proteins, including novel sources of safe foods and ingredients, are the candidates that could provide more environmentally sustainable choices, animal welfare, and consumers health. Novel foods and food proteins must undergo premarket safety evaluations including allergenicity assessment to reduce the risk of cross-reactivity with known allergens and uncharacterized risk to food allergic individuals. This research addressed the safety assessment of some novel foods and food ingredients using the study of stability of proteins in pepsin and sequence identity analysis in the …

Lactic Acid Bacteria Isolated From Fresh Vegetable Products: Potential Probiotic And Postbiotic Characteristics Including Immunomodulatory Effects, Fatima Khaled Alameri

Theses

The ability to perform effectively in the gastrointestinal system (GIT) is one of the most significant criteria for selecting the best probiotic bacteria. Thus, the present study aimed to investigate the potential probiotic characteristics of some selected lactic acid bacteria (LAB) isolated from vegetable products. Probiotic characteristics included tolerance to acid and bile, cholesterol removing ability, bile salt hydrolysis, resistance against lysozyme and antibiotics, production of exopolysaccharides (EPS), antimicrobial and hemolytic activities, and cell surface characteristics (auto-aggregation, co-aggregation, and hydrophobicity). Out of 46 isolates, 17 isolates that exhibited remarkable survivability under gastrointestinal conditions were selected for further analysis. Almost all …

The Rapid Enumeration Of A Mixed Culture Of S. Cerevisiae & L. Plantarum In Beer Using Image-Based Cytometry, Kevin M. Kennedy

Electronic Theses and Dissertations

Mixed cultures are prevalent in the food industry. From sour beer to sourdough bread, mix culture popularity is growing. A number of microbiological mixtures are used in these unique fermenting processes to create distinctive flavor profiles of consumers’ favorite foods. Although mixed cultures seem ubiquitous, they are often not well enumerated. The aim of this thesis was to create a novel rapid image-based cytometry method to enumerate mixed cultures in beer. Imaged-based cytometry can be used to rapidly enumerate mixed microbial cultures, as opposed to traditional plate counting methods that can take days to grow and count. A novel method …

Prevention Of Inflammatory Bowel Disease By Broccoli-Sourced And Microbially-Produced Bioactives, Johanna M. Holman

Electronic Theses and Dissertations

Inflammatory Bowel Diseases (IBD) are chronic, reoccurring, and debilitating conditions characterized by inflammation in the gastrointestinal tract, some of which can lead to more systemic complications and can include autoimmune dysfunction, a change in the taxonomic and functional structure of microbial communities in the gut, and complicated burdens in a person’s daily life. Like many diseases based in chronic inflammation, research on IBD has pointed towards a multifactorial origin involving factors of the host’s lifestyle, immune system, associated microbial communities, and environmental conditions. Too often, research focuses on just one aspect of IBD or uses one model with a narrow …

Comparative Assessment Of Human Exposure To Antibiotic-Resistant Salmonella Due To The Consumption Of Various Food Products In The United States, Yifan Wu

Dissertations, Theses, & Student Research in Food Science and Technology

Antibiotic resistance (AR) was increasingly recognized as a global and national problem. Prevention efforts are hampered by a lack of complete understanding of how transmission pathways contribute to human AR exposure. Many reports have indicated the presence of antibiotic-resistant bacteria in foods at retail, suggesting that food consumption, animal-derived foods in particular, can represent a significant source of AR exposure among consumers. The presence of Salmonella, including antibiotic-resistant Salmonella, has been frequently reported in terrestrial animal-derived foods such as meat, poultry, and dairy products, as well as in aquaculture products. Identification of the significant food sources that harbor …

Microbial, Chemical, And Functional Components In Kefir, Natto, And Feed Ingredients, Dana Mccurdy

All Dissertations

Kefir grains were purchased from online, home kitchen vendors in the United States (n = 22), inoculated into UHT milk, and incubated at 25°C for 22 hours. Results indicated lactobacilli, lactococci and yeast in all samples. Six out of 11 samples contained coliform, and all samples contained pseudomonal and staphylococcal species. Using targeted genome sequencing (16S) of kefir grain samples 1, 2, and 3 revealed that lactobacilli were the predominant genera of bacteria. ITS sequencing revealed different fungal species in each grain. Results indicated potential presence of menaquinone-4 and menaquinone-7 by UPLC-MS/MS analysis.

The fermentation of whole and ground soybeans, …

Allelopathic Effect Of Cereal Straw Extracts On Growth Of Raphidocelis Subcapitata And Microcystis Aeruginosa, Holly Wren

Graduate Theses and Dissertations

Harmful algal blooms are increasing in size, duration, and intensity around the globe. For several decades, cereal straws have been recognized as a viable algal control method, though the mechanisms by which cereal straws inhibit algae remain a topic of research. The objectives of this study were to evaluate the effectiveness of decomposing cereal straw extract, particularly rice (Oryza sativa) and barley (Hordeum vulgare) straw extract, to inhibit the green alga Raphidocelis subcapitata or cyanobacteria Microcystis aeruginosa in bioassays and to determine if the effectiveness of decomposing rice straw extract is altered by the presence of natural organic matter or …

Bacterial Chondronecrosis With Osteomyelitis In Broilers: Genomics, Phylogenomics, And Methods To Detect Specific Pathogens During Outbreaks., Abdulkarim Abdulaziz A. Shwani

Graduate Theses and Dissertations

Lameness is a major issue in animal welfare and the broiler industry. Bacterial chondronecrosis with osteomyelitis (BCO) is one of the main causes of lameness. Many staphylococcal species, including Staphylococcus agnetis isolate 908, have been isolated from the bones and blood of lame broilers at the University of Arkansas. Staphylococcus agnetis is a coagulase-variable, Gram-positive bacterial species that has been previously associated with subclinical or mild clinical cases of mastitis in dairy cattle. The annotated complete genome of hypervirulent strain 908 was published at NCBI. In this study, it has been compared to nine genomes we assembled for hypervirulent isolates …

The Role Of Microbiota On Campylobacter Jejuni Colonization And Growth Performance In Broiler Chickens, Ayidh Almansour

Graduate Theses and Dissertations

The successful poultry production at modern era comes from the vertical integratedindustrialization, which has fundamentally changed how animals have been living for millions of years. Antimicrobial growth promoters have been used to sustain the efficient industrialized animal production, driving antimicrobial overuse and resistance. Because of the increasing pressure from consumer’s concerns and government regulations, it is urgent to develop antimicrobial free alternatives as growth promoters in poultry production, but few effective antimicrobial alternatives are currently available. Campylobacter jejuni is one of the worldwide prevalent foodborne bacterial pathogens mainly transmitted from poultry. However, few mechanisms are available on why C. jejuni …

The Biological Activity Of Tea Tree Oil And Hemp Seed Oil, Lakatos Lakatos, Samuel Obeng Apori, Julie Dunne, Furong Tian

Articles

The interest in hemp seed oil (HSO) and tea tree oil (TTO) in the medical and food industries is increasing. The current study compares their bioactivity to other plant oils, mainly focusing on hemp seed oils (HSOs) with various cannabidiol (CBD) contents. A DPPH assay was employed to evaluate the antioxidant activity. The antimicrobial activity against Escherichia coli, Staphylococcus aureus, and Salmonella enteritidis was evaluated using time–kill, minimum inhibition concentration (MIC), and Kirby–Bauer disk diffusion methods. Tea tree oil showed significantly higher antimicrobial activity against S. enteritidis compared to E. coli and S. aureus (p < 0.05). The antioxitant activity range (lowest to highest) was sesame < vetiver < rosehip < tea tree < organic hemp < pure hemp < 5% CBD < vitamin C. Tea tree oil and 5% CBD showed antioxidant activity at IC50 of 64.45 μg/mL and 11.21 μg/mL, respectively. The opposing antimicrobial and antioxidant results for TTO and HSO indicate that these activities arise from different components within the oil compositions.

Differential Effects Of Protein Isolates On The Gut Microbiome Under High And Low Fiber Conditions, Marissa Behounek

Dissertations, Theses, & Student Research in Food Science and Technology

Protein isolates are a growing market share in the food industry both as food ingredients and as supplements. All dietary habits can influence and alter the gut microbiome; however, little is known about how protein isolates from different sources will change the composition and function of the gut microbiota under high and low fiber conditions. The study aims to determine the microbiome response to plant and animal protein isolates under high- and low-dietary fiber (H/LDF) conditions. Six commercially available protein isolates (beef, egg white, milk, pea, and two soy protein isolates) were subjected to in vitro enzymatic digestion and dialysis …

Enhancement In Photoinactivation Of Food-Borne Pathogenic Bacteria With The Use Of Curcumin And Surfactants, Victor Ryu

Doctoral Dissertations

Photosensitizers and UV or visible light could photoinactivate bacteria. Curcumin was utilized as a food-grade photosensitizer, and an enhancement of its water-dispersibility, chemical stability, and antimicrobial activity when introduced into surfactant solutions was observed. Stock curcumin-surfactant solutions were prepared by titrating curcumin dissolved in ethanol into either Surfynol 465 or Tween 80 solutions (5 mM sodium citrate buffer). Stock curcumin surfactant solutions with different surfactant concentrations were diluted to 1 µM prior to irradiation. The resulting solutions also had surfactant concentrations below, near, and above their critical micelle concentrations (CMCs) of the respective surfactants. The antimicrobial activity of the curcumin-loaded …