Food Microbiology Commons^™

Use Of Gamma Irradiation As An Intervention Treatment To Inactivate Escherichia Coli O157:H7 In Freshly Extracted Apple Juice, Dielle Aurelia Fernandes

Food Science (MS) Theses

Escherichia coli O157:H7 can contaminate dropped apples used for juicing via contact with manure or fecally tainted irrigation water and attach to the flesh of the apple through bruises and wounds where surface sanitizers are not effective. The goal of this project was to determine the efficacy of gamma irradiation at the maximum allowed dose of 1000 Gy to inactivate Escherichia coli O157: H7 in whole apples used for juicing. Whole apples were punctured to simulate wounds which were then inoculated with an outbreak strain of E.coli O157:H7 and subjected to gamma irradiation at doses upto 1000 Gy. The D-value …

Antimicrobial Properties Of Different Chitosans Against Gram-Negative And Gram-Positive Foodborne Pathogens In Food Products, Nancy Katherine Rubio Zapata

LSU Doctoral Dissertations

Chitosan is a polymer derived of the deacetylation of chitin that is one of the most abundant material in nature. Chitosan solutions applied as edible coatings, and dipping solutions have shown positive results in the extension of shelf life on seafood and meat products. The purpose of this study was to evaluate the antimicrobial activities of a newly invented high molecular weight water-soluble (HMWWS) chitosan against selected Gram-negative (Salmonella Typhimurium, Vibrio parahaemolyticus, Vibrio vulnificus, and Vibrio cholerae) and Gram-positive (Listeria monocytogenes, Staphylococcus aureus, and Bacillus cereus) foodborne pathogens (initial inoculation of 6.5 Log). Chitosans with …

Characterization Of Bacterial Isolates Obtained From Commercial Poultry Feed And Retail Food Using Whole Genome Sequence Analysis And Selected Biochemical Tests, Elena George Olson

Electronic Theses & Dissertations

The goals of this study is two-fold. The first part investigates bacterial isolates from commercial poultry feed and the second part deals with bacterial isolates recovered from retail food. In order to reduce pathogen contamination in poultry products identification of overall microbial populations in poultry production processing steps have always been considered an important monitoring tool for assessing sanitizer effectiveness and the corresponding responses of bacteria load levels on poultry carcasses. Bacterial isolates recovered from corn-based chicken feed were purified on aerobic plate count agar and eleven morphologically different colonies were selected for whole genome sequencing. In this part, the …

Improving The Food Safety Of Louisiana Strawberry Industry, Jose L. Brandao Delgado

LSU Doctoral Dissertations

Escherichia coli O157:H7, Salmonella sp., and Listeria monocytogenes have been linked to foodborne outbreaks in produce. The most recent outbreaks in produce have been associated with irrigation water due to infiltration of well water or water run-off from contaminated sources. The Food Safety Modernization Act (FSMA) requires all irrigation water to be safe for use on produce, as a strategy to reduce foodborne illnesses. A surfactant modified zeolite (SMZ) filtration system could provide produce farmers with a sustainable low-cost system for high-quality and safe irrigation water. The objective of this study was to evaluate the effectiveness of hexadecyltrimethylammonium …

Reducing The Risk: Psychological And Technological Approaches For Improving Handwashing Practices In The Foodservice Industry, Jeffrey Allan Clark

Graduate Theses and Dissertations

As Americans are spending greater portions of their dollar on food consumed outside the home, the foodservice industry plays more of an integral part of daily existence compared to previous generations. Given the numerous annual foodborne illness outbreaks that threaten human lives while undermining confidence in the food supply, food safety is a pertinent issue for industry stakeholders, government regulators, and consumers. Food worker handwashing reduces the risk of foodborne illness transmission, yet compliance with this simple behavior is a complex problem. This dissertation addresses, predominantly, the issue of sub-optimal handwashing practices through applying psychology and technology, including wearable computers …

Characterization And Evaluation Of The Probiotic Properties Of The Sporeforming Bacteria, Bacillus Coagulans Unique Is-2, Amy Garrison

Department of Food Science and Technology: Dissertations, Theses, and Student Research

Probiotics are live organisms, that when consumed in adequate amounts, confer a health benefit to the host. To achieve probiotic status, each potential strain’s functional properties and their safety to the consumer must be comprehensively evaluated. Probiotic effects have been observed to be strain specific, therefore each new strain of interest must be characterized according to their phenotypic and genetic characteristics. There is a list of characteristics that potential probiotic strains should have to be considered as a probiotic. Potential probiotic strains should be evaluated for their acid and bile salt resistance, antimicrobial activity and adherence and colonization to intestinal …

The Impacts Of Administering Metabolites Of Saccharomyces Cerevisiae On Broiler Performance, Yields And Salmonella Content Of Component Portions, Bill Douglas Potter

Graduate Theses and Dissertations

The impacts of using health-promoting Saccharomyces cerevisiae fermentation metabolites in poultry production and processing can be measured in respect to multiple measures of success. Traditionally this yeast-based compound has been administered to poultry, livestock, poultry, and other species to improve animal performance and production volume output. In addition, Saccharomyces cerevisiae fermentation metabolites have also been shown in more recent research to reduce colonization of pathogenic bacteria in the host organism’s gastro-intestinal tract. In this dissertation, the impacts of administering a functional ingredient containing Saccharomyces cerevisiae metabolites on broiler performance measures and pathogen reduction were measured. One of the studies in …

You Are What You Eat At Any Age: Carbon And Nitrogen Analysis Of Mummies From An Ancient Egyptian Necropolis, Stephen Funk, R. Paul Evans

Library/Life Sciences Undergraduate Poster Competition 2019

The BYU Egypt Project at Fag el-Gamus necropolis and adjacent Seila Pyramid has studied over 700 mummies excavated over the past 30 years. The necropolis includes an open area with densely located vertical burial shafts and a hill with horizontal burial shafts. The chronological and dietary history of the mummies was assessed using stable isotopy and 14C analysis of accessible biological samples.

Efficacy Of Aqueous And Gaseous Chlorine Dioxide In Reducing Salmonella, E. Coli O157:H7, And Listeria Monocytogenes On Sweet Potatoes, Strawberries, And Blueberries, Phillip Luu

LSU Master's Theses

Chlorine dioxide, a stronger oxidizing agent, is effective against a broad spectrum of microorganisms. This study evaluated the efficacy of chlorine dioxide on reducing Salmonella, E. coli O157:H7, and Listeria monocytogenes on sweet potato (aqueous ClO₂), strawberries and blueberries (gaseous ClO₂). Sweet potatoes inoculated with multi-strain cocktails of each bacterial pathogen (10⁷ CFU/cm²) were treated with 5 ppm aqueous ClO₂ or water for 10, 20, and 30 minutes. Strawberries and blueberries spot inoculated with multi-strain cocktails of each bacterial pathogen (10⁷ CFU/g) were treated with gaseous ClO₂ sachets (63 mg/l for strawberry and 30 mg/l for blueberry) …

Effect Of Fermentation On Enhancing The Nutraceutical Properties Of Arthrospira Platensis (Spirulina), Elena Demarcocastro, Emer Shannon, Nissreen Abu-Ghannam

Articles

Abstract:Arthrospira platensis(spirulina), a filamentous fresh-water planktonic cyanobacterium,possesses diverse biological activities and a unique nutritional profile, due to its high contentof valuable nutrients. This study aimed to further improve the bioactive profile of spirulina, byfermenting it with the lactic acid bacteriumLactobacillus plantarum.In vitrocomparison of thetotal phenolic content (TPC), C-phycocyanin, free methionine, DPPH radical scavenging capacity,ferric reducing antioxidant power (FRAP), oxygen radical absorbance capacity (ORAC) and proteinfragmentation via SDS-PAGE in untreated versus 12 to 72 h fermented spirulina is reported here.After 36 h fermentation, TPC was enhanced by 112%, FRAP by 85% and ORAC by 36%. After 24 h,the DPPH radical scavenging …

Effect Of Environmental Factors And Residual Sanitizers On Survival And Attachment Of Indicator Organism And Human Pathogens On Fresh Produce, Vijay Singh Chhetri

LSU Doctoral Dissertations

A comprehensive understanding of the behavior of microbial contaminants on produce surfaces in agricultural farms and during post-harvest activities is essential for the development of produce safety risk management strategies. Our studies investigated the survival and the attachment of E. coli on watermelon surfaces in agricultural settings with different levels of vegetation, and the effect of residual sanitizers on the survival and the attachment of E. coli O157: H7 and L. monocytogenes on spinach leaves. The attachment strength (S_R) of the E. coli cells on watermelon surfaces significantly increased (P<0.05) from 0.04 to 0.99 in the first 24 h, which was primarily due to the decrease in loosely attached population, given that the population of strongly attached cells was constant. The daily die-off rate of E. coli ranged from -0.12 …

A Comparative Analysis Of The Fermentation Capabilities Of Various Bifidobacterium Strains, Ella Oney

Honors Program: Senior Projects (Public)

Bifidobacterium is a genus of anaerobic bacteria that are commonly found to inhabit the gastrointestinal tract of many members of the animal kingdom. These microorganisms are adapted to obtain their carbon from the breakdown of complex carbohydrates. Marmosets, a mammal whose gut microbiome is inhabited by high levels of Bifidobacteria, consume gum Arabic as a major part of their diet. The purpose of this experiment is to determine whether Bifidobacterium strains isolated from the guts of marmosets are able to degrade and ferment this complex carbohydrate or one of its main constituents, arabinose. This was accomplished by inoculating isolates of …

Combined Effects Of Calcium Ascorbate Treatment And Modified Atmosphere Packaging To Improve Quality Retention Of Fresh-Cut Cantaloupes, Joongmin Shin, Kevin Mis Solval, Bob Xiang, Youn Suk Lee

Journal of Applied Packaging Research

The impact of passive modified atmosphere packaging technique (MP) and calcium ascorbate (CA) on the extension of freshness and shelf life in fresh-cut cantaloupe was studied at two storage temperatures (4 and 10°C). Fresh cantaloupes were cut into uniform size cubes (25.4 mm x 25.4mm x 25.4mm). Then, half of the fresh cut cubes was dipped into the treatment solution, and the others were not. Clamshell tray with snap-on lid (control) and micro-perforated sealable lid (MP) was used as the fresh cut fruits packaging. Fresh cut cantaloupes in CA and MP combination (CA-MP) observed the highest quality preservation among the …

Hydrodynamic Cavitation As In-Line Process To Control Common Dairy Sporeformers, Pratibha Chaudhary

Electronic Theses and Dissertations

Sporeforming bacteria and their endospores have the ability to survive thermal treatments and proliferate in the milk and dairy products to cause spoilages. We applied the effect of hydrodynamic cavitation in controlling these bacteria and their spores at pilot scale level. Our aim was to investigate a technology that would improve the microbial quality of milk and dairy products, and is capable of being scaled up to be adapted at industrial level. Cavitation damages the cell walls of the bacteria and their endospores (releasing dipicolinic acid, responsible for endospore resistance to extreme conditions), thereby making them susceptible to thermal treatments …

Metabolic And Morphological Evaluation Of Two Brewer’S Yeast Strains Throughout Serial Re-Pitching In Beer Fermentation, Anh Pham

All Graduate Theses, Dissertations, and Other Capstone Projects

Beer fermentation is the process of growing yeast anaerobically in a malt-based medium, ultimately resulting in alcohol and carbon dioxide production. In order to reduce the cost and waiting time, serial repitching has been practiced among microbrewers. The technique emphasizes transferring yeast from one batch of beer to the subsequent brewing cycles. It has been shown that aged yeast cultures have higher fermentation efficiency and shorter lag period, thereby resulting in shorter fermentation times, faster pH drop, and lower concentrations of unwanted products. Despite the advantages of serial repitching, one can only practice repitching for approximately 5-6 times with a …

Degradation Kinetics Of Cold Plasma-Treated Antibiotics And Their Antimicrobial Activity, Chaitanya Sarangapani, Dana Ziuzina, Patrice Behan, Daniela Boehm, Brendan F. Gilmore, Patrick J. Cullen, Paula Bourke

Articles

Antibiotics, such as ofloxacin (OFX) and ciprofloxacin (CFX), are often detected in considerable concentrations in both wastewater effluents and surface water. This poses a risk to non-target organisms and to human health. The aim of this work was to study atmospheric cold plasma (ACP) degradation of antibiotics in water and meat effluent and to explore any residual antimicrobial activity of samples submitted to the plasma process. The results revealed that ACP successfully degraded the studied antibiotics and that the reaction mechanism is principally related to attack by hydroxyl radicals and ozone. According to the disk diffusion assay, the activity of …

Spent Coffee Waste As A Potential Media Component For Xylanase Production And Potential Application In Juice Enrichment, Rajeev Ravindran, Gwilym Williams, Amit Jaiswal

Articles

In this study, spent coffee waste (SCW) was used as the sole carbon source for xylanase production in solid state fermentation mode using Aspergillus niger. A Box–Behnken design was constructed using three parameters viz. temperature, initial moisture content, and log number of sporestodeterminetheoptimalfermentationcondition. Thebestfermentationconditionsforxylanase productionwerefound to beincubation at30◦Cwith aninitial moisture contentof 70%and usingan inoculum of 6.5×106 spores/g of dry SCW. Furthermore, the design of experiments revealed that maintaining a medium composition of 0.2 g of yeast extract, 0.04 g of K2HPO4, and 0.03 g of MgSO4 increased xylanase production. Under optimised solid-state fermentation conditions an enzyme activity of 6495.6 IU/g …

Antimicrobial Effects Of Microwave-Induced Plasma Torch (Minimip) Treatment On Candida Albicans Biofilms, Oliver Handorf, Uta Schnabel, André Bösel, Thomas Weihe, Sander Bekeschus, Alexander C. Graf, Jörg Ehlbeck

Articles

The susceptibility of Candida albicans biofilms to a non-thermal plasma treatment has been investigated in terms of growth, survival and cell viability by a series of in vitro experiments. For different time periods , the C. albicans strain SC5314 was treated with a microwave-induced plasma torch (MiniMIP). The MiniMIP treatment had a strong effect (reduction factor (RF) = 2.97 after 50 s treatment) at a distance of 3 cm between the nozzle and the superior regions of the biofilms. In addition, a viability reduction of 77% after a 20 s plasma treatment and a metabolism reduction of 90% after a …

The Evaluation Of Pathogen Survival In Dry Cured Charcuterie Style Sausages, Jennifer Michelle Mcneil

Theses and Dissertations--Animal and Food Sciences

The objective of this study was to evaluate the survival of non-O157:H7 STEC, Salmonella spp., and S. aureus in dry fermented sausages. Chorizo and Landjager sausages were inoculated with individual bacterial cocktails and stuffed into natural casings. Temperature, relative humidity, pH, and water activity were monitored through fermentation, drying, and storage. Bacterial counts were determined by serial dilution and plated in triplicates on selective media. Plates were incubated at 37°C for 24 hours and colony forming units per gram (CFU/g) were observed.

Results of the first study validate that contaminated raw materials contribute to pathogen survival and background bacteria outcompeted …

Development And Diagnostics Of Novel Non-Thermal Plasmatreatment Systems, Laurence Scally

Doctoral

Non-thermal plasma (NTP) has been a point of interest in many areas over the last few decades. Much research has been,and continues to beundertaken,to understand the fundamentals of plasma discharges. This is such a broad topic due to the very nature and variable dependencies that set the conditions for plasma discharge to occur. This can come in the form of electrode geometry and spacing, dielectric barrier thickness, humidity of environment, material selection for electrodes and dielectric barriers, the power supply used, and the operating gas(es) used. A lot of these influencing factors can be set and kept constant, but still …

Efficacy Of Cold Plasma Functionalised Water For Improving Microbiological Safety Of Fresh Produce And Wash Water Recycling, Apurva Patange, Peng Lu, Daniela Boehm, Patrick J. Cullen, Paula Bourke

Articles

Atmospheric cold plasma (ACP) is an effective method for microbiological decontamination. This study evaluated an alternative water-based decontamination approach for inactivation of bacterial population from fresh produce and in the wash water generated from fresh produce washing. The study characterised ACP inactivation of attached Listeria innocua and Pseudomonas fluorescens inoculated on lettuce in comparison to chlorine treatment. P. fluorescens was sensitive to ACP treatment and was reduced below detection limit within 3 min of treatment. L. innocua population was reduced by ∼2.4 Log10 CFU/g after 5 min of treatment; showing similar inactivation efficacy to chlorine treatment. The microbial load in …

High Voltage Atmospheric Cold Air Plasma Control Of Bacterial Biofilms On Fresh Produce, Apurva Patange, D. Boehm, Dana Ziuzina, Patrick J. Cullen, Brendan Gilmore, Paula Bourke

Articles

Atmospheric cold plasma (ACP) offers great potential for decontamination of food borne pathogens. This study examined the antimicrobial efficacy of ACP against a range of pathogens of concern to fresh produce comparing planktonic cultures, monoculture biofilms (Escherichia coli, Salmonella enterica, Listeria monocytogenes, Pseudomonas fluorescens) and mixed culture biofilms (Listeria monocytogenes and Pseudomonas fluorescens). Biotic and abiotic surfaces commonly occurring in the fresh food industry were investigated. Microorganisms showed varying susceptibility to ACP treatment depending on target and process factors. Bacterial biofilm populations treated with high voltage (80 kV) ACP were reduced significantly (p <  0.05) in both mono- and mixed species biofilms after 60 s of treatment and yielded non-detectable levels after extending treatment time to 120 s. However, an extended time was required to reduce the challenge mixed culture biofilm of L. monocytogenes and P. fluorescens inoculated on lettuce, which was dependent on biofilm formation conditions and substrate. Contained treatment for 120 s reduced L. monocytogenes and P. fluorescens inoculated as mixed cultures on lettuce (p <  0.05) by 2.2 and 4.2 Log10 CFU/ml respectively. When biofilms were grown at 4 °C on lettuce, there was an increased resistance to ACP treatment by comparison with biofilm grown at temperature abuse conditions of 15 °C. Similarly, L. monocytogenes and P. fluorescens exposed to cold stress (4 °C) for 1 h demonstrated increased tolerance to ACP treatment compared to non-stressed cells. These finding demonstrates that bacterial form, mono versus mixed challenges as well as environmental stress conditions play an important role in ACP inactivation efficacy.

Effect Of Cold Plasma On The Techno-Functional Properties Of Animal Protein Food Ingredients, Juan M. Pérez-Andrés, Carlos Álvarez, Patrick J. Cullen, Brijesh K. Tiwari

Articles

Proteins, as food ingredients, are employed in the food industry, not only for their high nutritional value, but also because of their techno-functional properties. Modifications of their native structure due to the action of external factors such as pH, temperature or processing by emerging technologies, can lead to changes in their functionality; and consequently, their applicability. The present study investigates the effects of cold atmospheric air plasma on the techno-functional properties of two common food ingredients (haemoglobin and gelatine from pork), and a novel source of functional proteins extracted from a meat co-product (bovine lung protein). Significant effects were found …

Assessment Of Salmonella Enterica Biofilms And Expression Differences Among Serovars, Zhaohao Shi

Graduate Theses and Dissertations

Biofilms are communities of microorganisms associated by a matrix of extracellular polymers. In this state, microorganisms occupy an ecological niche distinct from their free-floating, planktonic counterparts. Also, biofilm bacteria become biologically unique as they form communities and lose motility. The acquisition of these physiological attributes enables the biofilm to persist through harsh environmental conditions, including antimicrobial induced stress and to resist sanitization efforts. Because of these features, biofilms can rapidly disseminate across numerous surfaces and as they establish, become challenging to remove. This is a particular issue for the food industry as processing plants offer favorable conditions for biofilm formation …

Efficacy Of Natural Compounds With Novel Carrier Systems For Controlling Campylobacter Jejuni In Post-Harvest Poultry, Sandip Shrestha

Graduate Theses and Dissertations

Campylobacter jejuni, a leading cause of bacterial gastroenteritis worldwide, is strongly associated with the consumption and/or mishandling of raw contaminated poultry products. Thus, interventions aiming to reduce C. jejuni counts on poultry products could greatly reduce the incidence of human campylobacteriosis. In the first study, the efficacy of a generally recongnized as safe (GRAS) compound, carvacrol (CR; derived from oregano oil), as an antimicrobial wash treatment to reduce C. jejuni on chicken skin was evaluated. Three delivery systems of CR: suspension, emulsion and nanoemulsion were used. C. jejuni counts were reduced up to 4 log10 cfu/sample by 2% dose of …

Aqueous Ozone Inactivation Of Viruses And Bacteria On Biotic And Abiotic Surfaces, Cailin Dawley

Graduate Theses and Dissertations

Produce is susceptible to contamination by foodborne pathogens. Food service establishments utilize sanitizing agents to reduce microbes on produce surfaces. The research objectives were to evaluate the efficacy of aqueous ozone 1) on the inactivation of viruses and bacteria on produce; 2) on the inactivation of viruses on stainless steel; and 3) against viruses in association with bacteria on produce surfaces. For objective 1, Boston bibb lettuce and cherry tomatoes were spot inoculated with a cocktail of viruses (murine norovirus (MNV) and MS2 bacteriophage) or bacteria (Enterobacter cloacae and Bacillus cereus) and washed for 40 min with samples taken every …

Efficacy Of Antimicrobial Mitigation On Escherichia Coli Cfu And Growth And Development Of Hydroponic Leafy Greens, Nathan J. Eylands

Graduate Theses and Dissertations

The Food and Drug Administration (FDA) have set new standards that apply to agriculturalists producing crops eaten fresh and/or raw by consumers. This new produce safety rule, known as the Food Safety Modernization Act (FSMA), has established science-based standards for all areas of production in agriculture with regards to microbial contamination. Escherichia coli (E. coli) O157:H7 is a particular bacterium of concern under FSMA guidelines. Grower compliance is mandatory and therefore vital to the continuation of any farm. Greenhouse hydroponic growers have shown advantages in efficiency when compared to conventional farming methodology. Those, however, with recirculating hydroponic systems face unique …

Microbiota Metabolic Product Deoxycholic Acid Prevents Campylobacter Jejuni Chicken Colonization Through Modulating Ceca Anaerobes, Bilal Ali Alrubaye

Graduate Theses and Dissertations

Campylobacter jejuni is a prevalent infectious enteritis mainly foodborne from chickens. Despite of reducing C. jejuni food contamination dramatically decreases campylobacteriosis, few effective approaches are available for the bacterial reduction in chickens. The aim of this study was to use microbial metabolic product deoxycholic acid (DCA) to reduce C. jejuni chicken colonization. Broiler chicks were fed 0 or 1.5 g/kg DCA, lithocholic acid (LCA), or urodeoxycholic acid (UDCA) in diets or orally gavaged with cholic acid (CA, 1.5g/kg body weight). Birds were also transplanted with DCA modulated anaerobes (DCA-Anearo) or aerobes (DCA-Aero). Birds were infected with 109 CFU/bird human clinical …

With-In Host Dynamics Of L. Monocytogenes And Thresholds For Distinct Infection Scenarios, Ashrafur Rahman, Daniel Munther, Aamir Fazil, Ben Smith, Jianhong Wu

Mathematics and Statistics Faculty Publications

The case fatality and illness rates associated with L. monocytogenes continue to pose a serious public health burden despite the significant efforts and control protocol administered by private and public sectors. Due to the advance in surveillance and improvement in detection methodology, the knowledge of sources, transmission routes, growth potential in food process units and storage, effect of pH and temperature are well understood. However, the with-in host growth and transmission mechanisms of L. monocytogenes, particularly within the human host, remain unclear, largely due to the limited access to scientific experimentation on the human population. In order to provide insight …

A Risk-Based Approach To Evaluate The Impact Of Interventions At Reducing The Risk Of Foodborne Illness Associated With Wheat-Based Products, Luis Sabillon

Department of Food Science and Technology: Dissertations, Theses, and Student Research

Pathogens are emerging on previously unrecognized food vehicles, such as wheat flour, which is a widely consumed commodity. Despite its low water activity, wheat-based ingredients and products have been implicated in several foodborne outbreaks over the last few years, resulting not only in the recall of food products but also in consumer illnesses. As a raw agricultural commodity, wheat is exposed to naturally occurring microbiological contamination that may compromise the overall safety of flour and other derived products. To address the increased concern regarding the safety of wheat-based foods, the objectives of the present research study were designed to develop …