Food Microbiology Commons^™

Surrogate-Based Approaches For Evaluating Post-Harvest Food Safety Interventions In Fresh Produce, Md Shafiul Islam Rion

Graduate Theses, Dissertations, and Problem Reports (ETD)

Pathogenic bacteria are still a threat to human beings worldwide as their presence is often unknown even if they are already present in fresh produces. This in turn resulted in several outbreaks and recalls across the United States. This dissertation investigated the survival of pathogenic bacteria and their potential non-pathogenic surrogates after antimicrobial interventions in different modes of applications on the surface of cantaloupes, butternut squash, and fresh cilantro. In the first study, peroxyacetic acid (PAA) was applied in three separate doses on nalidixic acid resistant Salmonella Typhimurium, Listeria monocytogenes, Enterococcus faecium, and Listeria innocua inoculated cantaloupe surfaces …

Inactivation Of E. Faecium Nrrl B-2354 In Whole Black Pepper By Fluidization With Hydrogen Peroxide Vapor, Daniela Segura

Department of Food Science and Technology: Master of Science with Project Option

This study evaluated Enterococcus faecium NRRL B-2354 as a surrogate for Salmonella inactivation in black peppercorns treated with hydrogen peroxide (HP) vapor via fluidization. The selected parameter for dwell temperature was 60ºC for 60 minutes. The reduction of both Salmonella and E. faecium, along with changes in water activity, color, and residual hydrogen peroxide, were measured before, immediately after treatment and at 24 and 48 hours post-treatment. Results showed that E. faecium exhibited a significantly greater reduction (4.63 ± 0.55 log CFU/g) compared to Salmonella (2.94 ± 0.16 log CFU/g) (p < 0.05), making E. faecium unsuitable as …

Salmonella Detection In Food Using A Hek-Htlr5 Reported Cell-Based Sensor, Esma Eser, Victoria A. Felton, Rishi Drolia, Arun K. Bhunia

Biological Sciences Faculty Publications

The development of a rapid, sensitive, specific method for detecting foodborne pathogens is paramount for supplying safe food to enhance public health safety. Despite the significant improvement in pathogen detection methods, key issues are still associated with rapid methods, such as distinguishing living cells from dead, the pathogenic potential or health risk of the analyte at the time of consumption, the detection limit, and the sample-to-result. Mammalian cell-based assays analyze pathogens’ interaction with host cells and are responsive only to live pathogens or active toxins. In this study, a human embryonic kidney (HEK293) cell line expressing Toll-Like Receptor 5 (TLR-5) …

Growth Of Food-Borne Pathogens Listeria And Salmonella And Spore-Forming Paenibacillus And Bacillus In Commercial Plant-Based Milk Alternatives, Klaudia Bartula

ORBioM (Open Research BioSciences Meeting)

An increase in vegan diet preference, lactose intolerance, calorie concern and environmental awareness has led to a rise in the popularity of plant-based alternatives to bovine milk. However, there are still gaps in understanding how known bacterial food contaminants behave in plant-based beverages. The present study is the first to compare the growth of food-pathogens Listeria monocytogenes and Salmonella enterica, food spoilage Bacillus subtilis and an industrial milk product isolate, spore-forming Paenibacillus in commercially available ultrahigh temperature processed bovine milk and plant-based milk alternatives (coconut, almond, cashew). Beverage samples were inoculated with a strain cocktail or individual strains of either …

Evaluating Salmonella Cross Contamination In Raw Chicken Thighs In Simulated Post-Chill Tanks, Raziya Sadat

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

Salmonella contamination poses a significant risk to food safety, particularly in poultry products and public health. This study aims to investigate the effectiveness of peracetic acid (PAA) treatment in mitigating Salmonella cross-contamination in chicken thighs within simulated post-chill tanks, considering different inoculum concentrations and organic matter (OM) levels.

The experiment involved the use of five distinct Salmonella serovars to inoculate chicken thighs, which were categorized into two groups: higher inoculation level (ca. 7 log CFU/mL) and lower inoculation level (ca, 4 log CFU/mL). These groups underwent treatment with four different solutions, including 540 ppm PAA with 1.5% OM, 540 ppm …

Microbiological Safety And Quality Of Ceviche, Poke, And Sushi Dishes Sold At Retail Outlets In Orange County, Ca, Grace E. Marquis, Samantha M. Covaia, Amanda M. Tabb, Courtney J. Kitch, Rosalee S. Hellberg

Food Science Faculty Articles and Research

Raw, ready-to-eat (RTE) seafood products, such as ceviche, poke, and sushi, have experienced growing demand globally; however, these products have the potential to be contaminated with foodborne pathogens. The objective of this study was to determine the prevalence of Escherichiacoli/coliforms, Salmonella, and Listeria in ceviche, poke, and sushi dishes sold at the retail level in Orange County, CA, USA. Additional organisms detected during testing were also considered in the results. A total of 105 raw, RTE samples of ceviche, poke, and sushi were collected from restaurants and grocery stores in Orange County, CA. Samples were tested for Salmonella …

Inhibiting Survival Of Salmonella During Desiccation Through The Use Of Naturally Occurring Signals, Joseph Headrick

Electronic Theses and Dissertations

A rising problem in agriculture is the increase of antibiotic-resistant Salmonella cases associated with chicken eggs, which transmit infection to humans. To counter this, new approaches to combat Salmonella in chickens and desiccated on eggshells are vital in the prevention of human foodborne illness. Disrupting signaling pathways with naturally occurring compounds provides a potential novel avenue for prevention of Salmonella infections, as this would disrupt sensing of these environments and inhibit subsequent optimal gene expression. Starting with signals identified in previous studies, salicylic acid was found to inhibit Salmonella desiccation survival on both eggshells and plastic. To expand upon this, …

Filth Flies As A Vector For Some Pathogenic Bacteria Transfer, Ahmet Buyukyavuz

All Dissertations

Two separate sets of experiments were conducted to determine the transfer of bacteria by flies. An Escherichia coli ampicillin-resistant strain with a fluorescent gene was used during the experiments. The first set of experiments were divided into two trials to measure the transfer of E. coli by fruit flies to apple slices and bologna during short term exposure. Short time exposure (1, 5 and 15 min) of flies to inoculated apple slices were tested in the first trial to determine the transfer of E. coli to flies. No difference (P>0.05) in the number of bacteria transferred to flies were …

Impacts Of Temperature And Salt Concentrations For Thermal Inactivation Of Salmonella In Moisture Enhanced Reconstructed Chicken Patties, Alik D. Browning

Graduate Theses, Dissertations, and Problem Reports (ETD)

The purpose of this experiment is to determine the thermal kinetic parameters of Salmonella in moisture-enhanced, reconstructed ground chicken patties as affected by temperatures and salt concentrations. Salmonella is responsible for 35% of the foodborne illnesses associated with poultry products (Batz et al., 2011). Nonintact reconstructed chicken meat is mixed with brine solutions containing various salt and polyphosphate concentrations to increase water-holding capacity, decrease cooking losses, improve sensory tasting scores, and maintain the good quality of completed chicken products (Gill et al., 2004). Increasing salt concentrations within meats can increase the thermal inactivation of pathogens. In this study, Salmonella Typhimurium …

Evaluate A Mixer Of Hydrogen Peroxide And Peroxyacetic Acid To Mitigate Microbial Cross-Contamination Of Salmonella Typhimurium And The Surrogate Enterococcus Faecium During Triple-Washing Of Butternut Squash, Jesica M. Temple

Graduate Theses, Dissertations, and Problem Reports (ETD)

Background: Recent foodborne illness outbreaks have been linked to fresh fruits and vegetables. For public safety, awareness of the risks of contamination from foodborne pathogens that can occur during post-harvest farming practices is essential to prevent foodborne outbreaks. Controlling the spread of foodborne pathogens on produce requires proper washing procedures, antimicrobials and doses. Given the speed and diversity of the produce being distributed, local incidents may become international emergencies. Methods: Studies were included if they assessed the efficacy of antimicrobials and various washing procedures and had to conclude the mitigation of cross-contamination of foodborne pathogens on produce grown in the …

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

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

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 …

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.

Effectiveness Of Selected Pre-Enrichment Broths For The Detection Of Salmonella Spp. In Meat Analogs, Georgia L. Sampson, Shannon B. Ruelle, Lieuchi Phan, Donna Williams-Hill, Rosalee S. Hellberg

Food Science Faculty Articles and Research

With the increasing variety of meat analog products, it is important to verify that the methods used for Salmonella detection are effective. The objective of this study was to compare the efficacy of three pre-enrichment broths for the detection of Salmonella in meat analog burgers: the currently used Bacteriological Analytical Manual (BAM) broth (lactose broth with Triton X-100, LB-T), universal pre-enrichment (UP) broth, and buffered peptone water (BPW). Five different meat analog products (coded A-E) were inoculated with Salmonella serotypes (S. Enteritidis or S. Agona) following the Food and Drug Administration Method Modification and Method Extension Criteria for Existing …

Growth Of Foodborne Pathogens Listeria And Salmonella And Spore-Forming Paenibacillus In Commercial Plant-Based Milk Alternatives, Klaudia Bartula

ORBioM (Open Research BioSciences Meeting)

An increase in vegan diet preference, lactose intolerance, calorie concern and environmental awareness has led to a rise in the popularity of plant-based alternatives to bovine milk. Non-dairy products are a fast-growing food industry sector; however, there are still gaps in understanding how the known bacterial food contaminants behave in plant-based beverages. The present study is the first to compare the growth of food-pathogens Listeria monocytogenes and Salmonella enterica and an industrial milk product isolate, spore-forming Paenibacillus, in commercially available ultrahigh temperature processed (UHT) bovine milk and plant-based milk alternatives (coconut, almond, cashew). Beverage samples were inoculated with a strain …

To The Window, To The Wall: Improving Environmental Monitoring Protocols, Sarah Jones

Graduate Theses and Dissertations

Detecting microorganisms on environmental surfaces via an environmental monitoring (EM) program is part of a preventive food safety culture. Environmental monitoring should 1) verify that food safety plans are reducing cross-contamination risk from surfaces to food, 2) pinpoint microbial niches, and 3) prevent the transmission of pathogens. Environmental monitoring programs utilize EM tools, such as sponges, to sample food contact and non-food contact surfaces. However, EM tool selection is determined by the individual food firm. This dissertation evaluated and characterized factors influencing EM program effectiveness in the food industry. Specifically, this dissertation focuses on the release of microorganisms from EM …

Evaluating The Microbial Quality And Use Of Antimicrobials In Raw Pet Foods, Leslie Pearl Cancio

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

Raw meat-based diets (RMBDs) are emerging pet foods that pose food safety risks because of the potential presence of pathogens that could cause illness to humans. In this research, the microbial quality of select RMBD products sold by pet food companies online and the use of chemical antimicrobials to reduce the microbial load in chicken liver, a common RMBD ingredient, were evaluated.

Ground meat blends and livers from four animal species (beef, pork, chicken, turkey) were purchased from four online companies that delivers directly to consumers through parcel businesses. Products were procured at three different times during one year and …

Investigation Of A Novel Throughput Agent On Production Rate And Pellet Quality And The Development Of A Lab-Based Method To Predict Salmonella Reduction In Poultry Feed, Utilizing Varying Feed Manufacture Parameters, Timothy Paul Boltz

Graduate Theses, Dissertations, and Problem Reports (ETD)

Two experiments were conducted to evaluate a novel throughput agent and its mechanisms on production rate and pellet quality. An additional experiment using lab-based methods and models was conducted to predict Salmonella reduction in mash broiler feed. Feed mill pellet production rate is of great importance to integrated meat bird production. Feed hygienics are also of increasing concern for poultry producers.

In chapter 2, the effect of AZOMITE® (AZM) and varying inorganic phosphate sources (IPS) on pellet mill production rate and pellet quality was assessed. It is documented that the naturally abrasive properties of inorganic phosphate sources may scour the …

Assessing The Efficacy Of Bacteriological Analytical Manual (Bam) Enrichment Broths For Detection Of Salmonella Spp. In Meat Analogs, Georgia Sampson

Food Science (MS) Theses

Plant-based meat alternatives are gaining popularity as the number of market options increases. However, the recent appearance of these products on the market post-dates the validation of the current approach for isolating Salmonella from meat analogs. Therefore, the objective of this study was to compare the efficacy of the currently used Bacteriological Analytical Manual (BAM) pre-enrichment broth (lactose broth) with two additional broths (universal pre-enrichment broth and buffered peptone water) for the detection of Salmonella in five plant-based burger products. Each burger product was spiked with a Salmonella serotype (S. Enteritidis or S. Agona) that has previously been linked …

Process Interventions For Improving The Microbiological Safety Of Low Moisture Food Ingredients, Tushar Verma

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

The recurrence of Salmonella in low moisture foods and the implementation of the FSMA rule requires a need to validate legacy and novel processing technologies. In this dissertation, a legacy thermal (extrusion), a novel thermal (radiofrequency (RF) heating), and a non-thermal (chlorine dioxide) technology, were evaluated as intervention technologies for Salmonella in low moisture foods. The twin-screw extruder was performed at different levels of screw speeds, temperatures, moisture contents, and fat contents to understand the impact of processing conditions on Salmonella inactivation in oat flour. At temperature >65°C, the Salmonella population was below the detection limit. At 55°C, Salmonella reduction …

Microbial Challenge Studies Of Radio Frequency Heating For Dairy Powders And Gaseous Technologies For Spices, Xinyao Wei

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

Persistence, thermal resistance, and survival of Salmonella in low moisture foods (LMF) have resulted in several foodborne illness outbreaks. Both existing and novel pasteurization technologies need to be validated for microbial safety of LMF. In this dissertation, a framework for using radio frequency (RF) heating to enhance microbial safety of milk powders and egg white powder was established. Thermal inactivation kinetics of Salmonella in milk powders were determined to guide the dairy industry for identifying thermal processing conditions for pasteurization. Storage time showed no effect on the thermal resistance of Salmonella, which can simplify the process validation study in …

Improving Microbiological Safety Of Low Moisture Food Products Using Radio Frequency And Ethylene Oxide, Long Chen

Department of Agricultural and Biological Systems Engineering: Dissertations, Theses, and Student Research

Recent foodborne illness outbreaks in US associated with consumption of low-moisture foods (LMF) have heightened concerns of their microbial safety. Salmonella is a pathogen of major concern in LMF due to its ability to persist in low water activity (a_w) environments. The disadvantages of existing decontamination technologies for LMF call for novel and efficient intervention technologies. Radio frequency (RF) and ethylene oxide (EtO) were evaluated in this dissertation for improving microbial food safety and quality of LMF. Cumin seeds and inshell hazelnuts were selected as model foods.

It took < 2 min of stationary RF heating to achieve > 5 log reductions of Salmonella in cumin seeds without …

Food Safety Risk In An Indoor Microgreen Cultivation System, Gina Marie Misra

Graduate Theses and Dissertations

Microgreens are immature sprouts of edible plants, sharing some similarities with sprouted seeds and petite leafy greens. Since they are most often grown in containers in buildings or greenhouses, they present a new area for food safety research at the intersection of the built environment and produce farming. Contamination by human pathogens has been extensively studied in other types of produce typically eaten raw, including sprouted seeds, which have been implicated in numerous outbreaks of salmonellosis over the last several decades. There is a paucity of knowledge about the microgreen sector of the fresh-cut industry; thus, it was determined that …

Prevalence And Control Of Salmonella Spp. And Sanitary Indicator Microorganisms In Wild Caught And Farm Raised Catfish (Ictalurus Punctatus), Bilan Costley Jessie

LSU Doctoral Dissertations

Catfish inspections have transitioned from the U.S. Food and Drug Administration (FDA) to the United States Department of Agriculture (USDA). The USDA Food Safety and Inspection Service (FSIS) and Food Emergency Response Network (FERN) consider it important to assess the food safety risk associated with consuming catfish in the United States. Surveillance of farm-raised and wild-caught catfish for pathogens is relevant as a public safety protocol. The purpose of this study was to detect the prevalence of Salmonella spp., identify and examine isolates for antibiotic resistance to clinical treatments, evaluate the effectiveness of antimicrobial chemical treatments against Salmonella enterica, and …

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 …

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 …

Survival And Inactivation Of Salmonella Enterica And Human Norovirus On Consumer Contact Surfaces, Dorra Simmons

LSU Doctoral Dissertations

Salmonella enterica and human norovirus (HuNoV) are the leading cause of bacterial and viral gastroenteritis worldwide, respectively. One of the most important transmission routes of these pathogens is contaminated surfaces. In this study, we investigated the survival and the disinfection of Salmonella enterica serovar Typhimurium (S. Typhimurium) and HuNoV on selected consumer contact surfaces.

In the case of S. Typhimurium, formica laminate, stainless steel, and plastic cutting board surfaces were inoculated with different microbial loads of cells collected at log (6 h), stationary (24 h), or LTS (14 days) phases. The disinfection efficacy of two disinfectants (sodium hypochlorite or …

Four Legs Good, Two Legs Bad: How Slaughterhouse Safety Hasn’T Kept Up With The Times, Emily Ziemski

Capstones

From legal loopholes and outdated rules to undetectable infections and understaffing, the United States Department of Agriculture may not be doing all it can to make sure the American public’s health isn't at risk. As the people of the United States consume over 500 million pounds of beef a year, food safety policy and slaughterhouses are falling behind in proper procedural measurements in the beef industry.

emziemski.com/capstone

Experimental Approaches To Understand And Control Salmonella Infection In Poultry, Yichao Yang

Graduate Theses and Dissertations

Salmonella is a major foodborne pathogen around the world and chickens are the major reservoir to transmit Salmonella into the human food chain. For decreasing the infection of Salmonella, we developed six attenuated live vaccines based on Salmonella Enteritidis (SE) and Typhimurium (ST) for testing the cross-serovar and cross-serogroup protection from the challenge of Salmonella Heidelberg and Campylobacter jejuni. One of the constructed vaccine strain showed ability to protect against challenge from Salmonella Heidelberg. Even though some preventive approaches are able to decrease Salmonella colonization in the gastrointestinal tract of chickens or other farm animals, Salmonella transmission mechanisms remain unclear. …

Role Of Incompatibility Group 1 (Inci1) Plasmid-Encoded Factors On Salmonella Enterica Antimicrobial Resistance And Virulence, Pravin Raghunath Kaldhone

Graduate Theses and Dissertations

Foodborne illnesses are a leading cause of infectious diseases in the world. Among enteric organisms Salmonella is a key pathogen. It’s high prevalence in poultry and other food-animal sources make it imperative to study. Salmonella has the ability to modify its genetic content with help of mobile genetic elements such as plasmids. Incompatibiltiy group 1 (IncI1) plasmids are commonly reported in Salmonella. This study evaluates role on IncI1 plasmids in antimicrobial resistance and virulence in Salmonella. Genetic determinants of resistance and virulence are noted among our IncI1-containing Salmonella isolates. These genetic elements are also transferable and reported to carry respective …

Isolation, Detection, And Prevention Of Foodborne Bacteria In Irrigation Water And Dairy Food, Mohammed Saleemallah Alhejaili

LSU Doctoral Dissertations

Foodborne microorganisms can be beneficial to humans or cause disease. Salmonella is one of the most causative foodborne disease outbreaks in the U.S.A. Salmonella has been detected in surface water used in irrigation, and can survive for weeks to years in water. The purpose of the study was to detect low levels of Salmonella spp. by comparing surfactant modified zeolite (SMZ) filtration and Activated Carbon (AC) filtration with the Environmental Protection Agency (EPA) method 1200. Also, to determine the generic E.coli counts and if there was a direct correlation of Salmonella to generic E. coli in irrigation water. The EPA …