Browsing by Author "Eifert, Joseph D."

Now showing 1 - 20 of 118
  • Thumbnail Image
    The Affects of Explosively and Electrically Generated Hydrodynamic Shock Waves on the Bacterial Flora of Beef and Poultry
    Lorca, Tatiana Andrea (Virginia Tech, 2002-07-19)
    The affects of hydrodynamic shock wave treatment on the bacterial flora of raw beef and poultry were evaluated. Hydrodynamic shock waves were generated in an aqueous treatment medium by either the detonation of two types of explosive charges (explosively-generated hydrodynamic shock waves [EHSW]) (a binary or a molecular explosive) or by electrical discharge (high voltage arc discharge Hydrodyne (TM [HVADH; Hydrodyne, Inc.]). A variety of sample types (whole steaks, ground beef, a water and ground beef slurry) were used to determine the lethality affects of EHSW on cells of the marker microorganism Listeria innocua suspended in a simple broth medium. These sample types were used in order to evaluate the affects of the process not only on the surface, but throughout the bulk of the samples in order to determine whether EHSW could also be used as a non-thermal alternative to reduce the bacterial flora of non-intact or ground meats. The levels of psychrotrophic, lactic, and coliform populations on the surface of whole eye of round steaks submitted to EHSW processing did not differ (P> 0.05) from those of untreated whole eye of round steaks. Parameters expected to influence the nature, magnitude, and propagation of the hydrodynamic shock wave were also varied and evaluated in order to determine which individual parameter or combination of parameters affected the bactericidal potential of EHSW or HVADH processing. Treatment with EHSW failed (P > 0.05) to produce lethality effects on the psychrotrophic, lactic, and coliform populations of ground beef, regardless of the composition and mass of explosive used, the number of successive EHSW treatments used, the relative distance between the explosive charge and the top surface of the sample, or the temperature of the water used in the treatment chamber. EHSW processing did not change (P >0.05) the bacterial population of treated ground beef samples when compared to untreated controls during a five day refrigerated storage study. No lethality effects were observed (P >0.05) in ground beef samples treated by HVADH when samples were subjected to one, two, or three successive HVADH treatments. Minimal penetration of surface inoculated bacteria was observed for both beef steaks and boneless skinless chicken breasts subjected to EHSW and HVADH, respectively. In EHSW-treated beef eye of round steaks, marker bacteria were detected within the first 300 um of tissue below the inoculated surface, 50-100 um beyond the depth of untreated surface inoculated steaks. In HVADH-treated boneless skinless chicken breasts, marker bacteria were detected within the first 200 um below the inoculated surface, 50-100 um beyond the depth of untreated surface inoculated boneless skinless chicken breasts. This suggests that although no difference in the bacteriological populations was observed between EHSW treated, HVADH treated, and untreated control samples of whole steaks (and ground beef treated with both HVADH and EHSW), HVADH and EHSW treatments affect the movement of surface bacteria. United States Department of Agriculture (USDA) guidelines suggest intact beef steaks be cooked to achieve a cooked color appearance on the surface and raw poultry be cooked to an internal temperature of 77° C to inactivate the pathogens Escherichia coli O157:H7 and salmonellae which are of concern in beef and poultry, respectively. By following these guidelines during proper cooking, consumers achieve thermal inactivation of these pathogens. Since the movement of the marker bacterium observed in treated steaks and boneless skinless chicken breasts was minimal, proper cooking of the products would be expected to inactivate vegetative bacterial cells at this depth. Therefore, EHSW and HVADH treated whole beef steaks and boneless skinless chicken breasts would not be expected to pose a bacterial hazard if the products were properly cooked.
  • Thumbnail Image
    Airborne Campylobacter in a Poultry Processing Plant
    Johnson, Anjeanette Christina (Virginia Tech, 2010-05-29)
    Campylobacter is a foodborne pathogen commonly found in live poultry and raw poultry products. Identifying areas of contamination or modes of transmission during commercial processing can lead to strategies to reduce the level of Campylobacter on finished products. Monitoring levels of airborne Campylobacter may be useful for identifying the presence or relative concentration of the pathogen in a processing plant environment. In this study, air sampling was used to detect and quantify Campylobacter in a commercial chicken processing plant by location within the plant and collection time during the day. Air was sampled from evisceration and post-chill areas in a poultry processing plant on four days and at 4 hour intervals onto Campy-Cefex agar plates or gelatin filters that were subsequently transferred to Campy-Cefex agar plates. Additionally, pre-evisceration and post-chill carcass rinses were analyzed quantitatively for Campylobacter. The mean level of airborne Campylobacter was 5 CFU/1000L of air sampled (10% samples positive) in comparison with 413 CFU/mL from carcass rinses (70% samples positive). Higher concentrations were found in carcass rinse samples from pre-evisceration. Airborne Campylobacter was detected from the evisceration area more frequently than from the post-chill carcass area of the plant (P < 0.05). This study shows that airborne Campylobacter can be quantified with a selective agar and with gelatin filter collection. Further research is needed to prove the utility of airborne detection of Campylobacter for estimating the relative contamination level of live poultry flocks and the processing plant environment and the potential for cross-contamination.
  • Thumbnail Image
    Allyl isothiocyanate reduces Salmonella enterica Michigan and Listeria monocytogenes on the surface of whole cantaloupe (Cucumis melo L.)
    Duckson, Margaret Anne (Virginia Tech, 2014-04-24)
    Since 2006 there have been four Salmonella enterica and one Listeria monocytogenes foodborne outbreaks linked to whole cantaloupe fruit. No post-harvest intervention to reduce potential contamination on cantaloupe currently exists. The complex surface topography of netted cantaloupes aids bacterial attachment. This research evaluates the use of allyl isothiocyanate (AITC; a natural antimicrobial) to reduce populations of S. enterica Michigan and L. monocytogenes on the surface of cantaloupe. Fifty μl of S. Michigan or L. monocytogenes was inoculated onto whole ‗Athena‘ or ‗Hales Best Jumbo‘ (‗HBJ‘) cantaloupe fruit in 22 mm diameter circles and allowed to dry for 90 min. resulting in 6.60 log CFU/g. Cantaloupe received either AITC liquid or vapor, sterile deionized water, 200 ppm sodium hypochlorite per circle, or no treatment. All cantaloupes were stored in separate sealed glass desiccators for 1 or 24 h at 25°C or 35°C. To enumerate the bacteria following treatment, 22 mm sections of the rind were removed, homogenized and plated onto appropriate agar. Headspace analysis using Gas Chromatography-Mass Spectrometry (GC-MS) quantified the concentration of each AITC vapor treatment. The texture quality of the pericarp tissue of whole cantaloupes was evaluated after 24 h treatments, followed by two weeks of storage at 4°C. The concentration of vapor ranged from 3.4 to 19.6 μl AITC/L inside the desiccators. The liquid treatment reduced (P < 0.05) S. Michigan populations on ‗Athena‘ (3 log CFU/g) and L. monocytogenes on ‗HBJ‘ (2.6 log CFU/g). The longer exposure time to the AITC vapor (24 h versus 1 h) resulted in a greater reduction of both S. Michigan and L. monocytogenes on ‗Athena‘ and treatments at 35°C reduced microbial populations up to 4.5 times greater (P < 0.05). The highest vapor concentration reduced (P < 0.05) both pathogens at least 3.0 log CFU/g on ‗Athena‘ at 25°C. Generally, bacterial pathogens from the surface of ‗Athena‘ cantaloupe were reduced more than pathogens inoculated on the surface of ‗HBJ.‘ The application of AITC liquid or vapor is a natural alternative post-harvest treatment to 200 ppm free chlorine to reduce the level of bacterial contamination on cantaloupe surfaces for certified organic production.
  • Thumbnail Image
    Antibacterial Activity of Hydrogen Peroxide Against Escherichia Coli O157:H7 and Salmonella Spp. in Fruit Juices, Both Alone and in Combination With Organic Acids
    Schurman, John Jackson (Virginia Tech, 2001-07-18)
    The antibacterial efficacy of hydrogen peroxide treatments in four fruit juices was determined. Preservative free apple cider, white grape, and purple grape juice were inoculated with ~ 6.4 log CFU/ml of a five strain, acid adapted, nalidixic acid resistant E. coli O157:H7 cocktail. Orange juice was inoculated with a comparable Salmonella spp. cocktail. In the first study, 0.017% and 0.012% H₂O₂ was added in combination with 0.1% and 0.3% of the dominant organic acid (OA) to 4°C and 25°C juices, with samples taken each day for 21 days. H₂O₂ was a significant factor in all juices (p < 0.05) except white grape (lack of data), and both 0.017% H₂O₂ treatments reduced counts in apple cider, orange juice, and white grape to undetectable numbers within 48 hrs as cultured on tryptone soy agar + 0.05% nalidixic acid (TSAN). Treatments in purple grape juice were less effective overall, and more dependent on OA concentration (p < 0.001) than H₂O₂. There were instances where bacterial survival in apple cider, purple grape, and orange juice continued for 21 days after treatment, and sometimes outlasted the control. These occurrences were dependent on temperature (25°C) and H₂O₂ (0.012%), but not on OA. However, OA concentration was a significant factor (p < 0.05) overall in apple cider and purple grape juice, but not in orange juice. In the second study, 0.015% and 0.03% H₂O₂ was added to 10, 25, and 40°C apple cider and orange juice inoculated with 6.4 log CFU/ml E. coli O157:H7 and Salmonella spp. respectively. Only 0.03% H₂O₂ was effective in reducing counts to undetectable numbers in both juices. However, both temperature and H₂O₂ were significant factors (p < 0.0001) in bacterial destruction, with 0.03% H₂O₂ at 40°C giving undetectable numbers at ≤ 3 and ≤ 6 hours in orange juice and apple cider respectively. It has been demonstrated that at ~ ≥ 0.017%, H₂O₂ can provide a 5 log reduction of these pathogens in fruit juice. Increasing temperature and organic acid concentration can improve its rate of effectiveness in certain juices. However, sensory concerns may negate its use in some products.
  • Thumbnail Image
    Application of Bacteriophage in Food Manufacturing Facilities for the Control of Listeria monocytogenes and Listeria sp
    Reinhard, Robert Gordon (Virginia Tech, 2020-02-05)
    The purpose of this research was to determine if bacteriophage (phage) could be used to treat and reduce the incidence of Listeria in food manufacturing facilities, and thereby reduce the risk of food products being cross-contaminated with Listeria monocytogenes. Listeria incidence in food manufacturing ready-to-eat environments was surveyed at 31 ready-to-eat (RTE) food plants. A total 4,829 samples were collected from all locations. Nine (29%) facilities had zero samples positive for Listeria spp., whereas 22 (71%) had one or more samples positive. The total incidence of Listeria spp. in all RTE food plants was 4.5%. The effectiveness of phage against Listeria was determined when applied to stainless steel, polyurethane thermoplastic, and epoxy. Each material was inoculated with a cocktail containing L. monocytogenes and L. innocua (4 to 5-log10 CFU/cm2) and treated with two different concentrations of phage (2x10^7 and 1x10^8 PFU/cm2). Treated samples were held at 4 or 20°C for 1 and 3h. After treatment with phage, Listeria reductions ranged from 1.27–3.33 log10 CFU/cm2 on stainless steel, 1.17–2.76 log10 CFU/cm2 on polyurethane thermoplastic, and 1.19–1.76 log10 CFU/cm2 on epoxy. Listeria reduction occurred on all materials tested, under all conditions. Higher phage concentration, longer time, and higher environmental temperatures led to significantly (P<0.05) greater reduction of Listeria on stainless-steel and polyurethane thermoplastic. The effectiveness of a phage against Listeria spp. was evaluated in two food manufacturing facilities, operating at either 4°C or 20°C. First, a moderate application of a 2x10^7 PFU/mL phage was applied once per day over three days and samples were collected and analyzed for Listeria at 0, 24, 48 and 72 h. This phage treatment led to a decrease in the incidence of Listeria by 67%. A second application method was studied with phage being applied in the food manufacturing environment in an intensified manner (3 times in 18 hours) at a higher concentration of phage (1x10^8 pfu/mL). This intensified application led to a 32% overall reduction in the incidence of Listeria in the production environment. Applications of Listeria specific phage can be an additional intervention strategy for controlling pathogenic Listeria organisms in food production facilities.
  • Thumbnail Image
    Assessment of Educational Needs and Current Practices of Front-line Grocery Employees in the Deli and Bakery
    Robertson, Lynn Ann (Virginia Tech, 2010-06-11)
    Grocery store associates in the deli-bakery departments serve and prepare an increasing amount of ready-to-eat foods. This increases the need for a detailed, effective food safety training program in retail grocery establishments to prevent food borne illness. This research examines food safety knowledge, training preferences, needs, and current practices of grocery stores deli-bakery employees in Southwest and Southern Virginia. This research had two phases. Phase I: employees completed a thirty-four question needs assessment survey concerning background, food safety training needs, preferences and knowledge. Phase 2: 15 employees (from phase 1 locations) food behaviors were observed for approximately six hours each (89.05 hours total). Observational data collection focused on glove use, cross-contamination, and hand washing. The results showed that most grocery food handlers desired hands-on, interactive and one-on-one training that occurs frequently, but is short: less than two hours in length. Overall, most grocery food handlers had general safe food handling knowledge; however, the observational behavior data indicates behaviors do not reflect their knowledge. Greater than 95% understanding was found on the subjects of hand washing and glove use; however, these items were observed practiced incorrectly the most with bare hand contact with ready-to-eat foods and lack of hand washing prior to glove use. The creation of short, hands-on or interactive trainings for retail grocery food handlers that focuses on changing food handling and preparation behaviors may be more effective than current training.
  • Thumbnail Image
    Association of Campylobacter spp. Levels between Chicken Grow-Out Environmental Samples and Processed Carcasses
    Schroeder, Matthew William (Virginia Tech, 2012-04-20)
    Campylobacter spp. have been isolated from live poultry, production environment, processing facility, and raw poultry products. The detection of Campylobacter using both quantitative and qualitative techniques would provide a more accurate assessment of pre- or post harvest contamination. Environmental sampling in a poultry grow-out house, combined with carcass rinse sampling from the same flock may provide a relative assessment of Campylobacter contamination and transmission. Air samples, fecal/litter samples, and feed pan/drink line samples were collected from four commercial chicken grow-out houses. Birds from the sampled house were the first flock slaughtered the following day, and were sampled by post-chill carcass rinses. Quantitative (direct plating) and qualitative (direct plating after enrichment step) detection methods were used to determine Campylobacter contamination in each environmental sample and carcass rinse. Campylobacter, from post-enrichment samples, was detected from 27% (32/120) of house environmental samples and 37.5% (45/120) of carcass rinse samples. All sample types from each house included at least one positive sample except the house 2 air samples. Samples from house 1 and associated carcass rinses accounted for the highest total of Campylobacter positives (29/60). The fewest number of Campylobacter positives, based on both house environmental (4/30) and carcass rinse samples (8/30) were detected from flock B. Environmental sampling techniques provide a non-invasive and efficient way to test for foodborne pathogens. Correlating qualitative or quantitative Campylobacter levels from house and plant samples may enable the scheduled processing of flocks with lower pathogen incidence or concentrations, as a way to reduce post-slaughter pathogen transmission.
  • Thumbnail Image
    An awareness guideline on consumer food safety in Suriname
    Zweevel, Mayra C. (Virginia Tech, 2021-12-01)
    The Nationaal Instituut voor Voedselveiligheid Suriname (NIVS) which is established in the context of general food safety and protecting consumers from dangers associated with all foods sold in Suriname, gives the opportunity to develop food safety rules, regulation and raise awareness on topics regarding food safety. One opportunity of this Institute is to create awareness among the consumers who are part of the food supply chain (known as the farm to fork continuum). Historical data show that Suriname is not excluded from foodborne illness. The goal of this project and report was to educate consumers in Suriname on food safety best practices. To the authors knowledge, no reports were found on consumers food safety behavior and knowledge in Suriname. Therefore, these guidelines were developed to educate consumers on food safety behavior, and also food safety best practices based on different international prior studies. These food safety best practices are described under several different topics related to consumer behavior and food handling.
  • Thumbnail Image
    Beef Quality Assurance - Adding Value with E. coli Food Safety Focus
    Flowers, Charles Webb (Virginia Tech, 2011-12)
    “Doing the right thing” as recommended by cumulative results of successive National Beef Quality Audits 1990–2010 is demonstrating positive end product quality, wholesomeness and food safety progress. As producers continued to utilize BQA practices over a 10-20 year period during the 1990s and 2000s, and included additional value added practices, they began to realize premiums for BQA practices. The focus of this publication is the importance of minimizing opportunities for foodborne illness pathogen to occur throughout the life of beef cattle for young calves through harvest.
  • Thumbnail Image
    “Campus Cuisine: Reservations Anyone?”: Development of a Curriculum on Food Safety Best Practices for a University Dining Services Workforce
    Southerland, Anita M. (Virginia Tech, 2022-11-28)
    Food for thought, every year in the United States, foodborne illness accounts for notable losses of healthy life years. Given that food and water supplies are the basis for human survival, it seems likely that institutions of higher learning would be a logical place for a robust educational platform to be interjected. College students may not thrive securely as healthy, productive adults without foundational food safety skills and knowledge. Therefore, a short, interactive, engaging food safety curriculum was developed for college students working in Dining Services at Pensacola Christian College. The emphasis on collegiate dining services may exponentially mitigate the toll of foodborne illness as college campuses being one of the latter points of preparatory insertion of knowledge for building life skills and seeking advancement in education. The ultimate goal of this training is to provide a basis for food safety practices through strategic and cohesive training within the collegiate arena (in this case one university dining service team of 600-800 students).
  • Thumbnail Image
    Campylobacter jejuni and Salmonella spp. Detection in Chicken Grow Out Houses by Environmental Sampling Methods
    Kuntz, Thomas James (Virginia Tech, 2009-04-24)
    Campylobacter and Salmonella are foodborne pathogens commonly associated with raw poultry. Although there has been much research done on isolating these pathogens from poultry production environments using cloacal swabs, fecal samples, intestinal tract contents and dissection, research involving environmental sampling has been limited. New and/or improved environmental sampling methods may provide an easy, convenient, and less time-consuming way to collect samples. Coupling these sampling methods with PCR may provide a relatively simple, rapid, and robust means of testing for foodborne pathogens in a chicken house or flock prior to slaughter. Air, boot and sponge samples were collected from three commercial chicken grow-out houses located in southwestern Virginia when flocks were three, four, and five weeks old. Air samples were collected onto gelatin filters. Fecal/litter samples were collected from disposable booties worn over investigator's protective shoe coverings. Pre-moistened sponges were used to sample house feed pans and water dispensers on drink lines. A PCR method was used to qualitatively detect Campylobacter jejuni and Salmonella spp. Campylobacter jejuni was detected at each farm (house), across all three ages (3, 4, and 5 weeks), and from each sample type. Salmonella was not detected in any of the environmental samples. For all 270 samples, 41% (110/270) were positive for Campylobacter. Collectively, 28% (25/90) of air, 44% (40/90) of sponge, and 50% (45/90) of bootie samples were positive for Campylobacter. The methods used in this study are non-invasive to live animals, relatively rapid and specific, and could enable poultry processing facilities to coordinate scheduled processing of flocks with lower pathogen incidence, as a way to reduce post-slaughter pathogen transmission.
  • Thumbnail Image
    Cetylpyridinium chloride direct spray treatments reduce Salmonella on cantaloupe rough surfaces
    Saucedo-Alderete, Raúl O.; Eifert, Joseph D.; Boyer, Renee R.; Williams, Robert C.; Welbaum, Gregory E. (2018-08)
    Cetylpyridinium chloride (CPC) solutions (0, 0.5, or 1.0%) were applied to cantaloupe (Athena and Hale's Best Jumbo cultivars) rind plugs, either before or after inoculation with a broth culture of Salmonella Michigan (10(9) CFU/mL) and held at 37 degrees C for 1 or 24 hr. Rind plugs were diluted, shaken, and sonicated, and solutions were enumerated. Texture quality and color were evaluated over 14 days storage at 4 degrees C after 0 and 1% CPC spray applications. A 0.5 or 1.0% (vol/vol) application of CPC after Salmonella reduced the pathogen levels between 2.34 log CFU/mL and 5.16 log CFU/mL in comparison to the control (p<.01). No differences were observed in the firmness and color of 1% CPC treated cantaloupes. Salmonella concentrations on cantaloupes, treated with 1.0% CPC, were lower after 1 hr storage as compared to 24 hr. And, Salmonella on Athena surfaces were more susceptible to CPC spray treatments than on Hale's Best Jumbo. Practical applicationsCetylpyridinium chloride (CPC) is the active ingredient of some antiseptic oral mouth rinses, and has a broad antimicrobial spectrum with a rapid bactericidal effect on gram-positive pathogens. The spray application of CPC solutions to cantaloupe may reduce the level of Salmonella surface contamination during production from irrigation water and manure fertilizers and, during food processing by contaminated equipment and food handlers. Since the surfaces of cantaloupes are highly rough or irregular, bacteria can easily attach to these surfaces and become difficult to remove. Appropriate postharvest washing and sanitizing procedures are needed that can help control Salmonella and other pathogens on melons, especially on cantaloupes with nested surfaces. A direct surface spray application of CPC may be an alternative antimicrobial postharvest treatment to reduce pathogen contamination of cantaloupe melons, while providing an alternative to chlorine-based solutions.
  • Thumbnail Image
    Characterization of alpha-cyclodextrin inclusion complexes with trans-cinnamic acid in an acid-based beverage system
    Romano, Dina Lynn (Virginia Tech, 2008-04-11)
    In response to a need for a natural antimicrobial to replace sodium benzoate, cinnamic acid was chosen. Due to cinnamic acid's solubility issues, α-cyclodextrin was used as a host molecule to form an inclusion complex with the cinnamic acid molecule. The cinnamic acid: α-cyclodextrin inclusion complex was then characterized using phase solubility analysis, proton nuclear magnetic resonance (H-NMR), and solid inclusion. Phase solubility analysis verified the maximum amount of cinnamic acid that α-cyclodextrin was able to host. H-NMR was used to determine the complex association constant, determine the chemical shifts of available protons, and yield a stoichiometry for the complex. The solid inclusion complex allowed for a physical formation of the complex, yielding further information in support of the complex stoichiometry. Microbiological tests were also performed to quantify the antimicrobial abilities of the complex, the guest, and the host against the yeast Saccharomyces cerevisiae and mold Paecilomyces variotii. Results indicated that approximately 990.29 ppm in aqueous solution was the maximum amount of cinnamic acid in the complex. The 2:1 stoichiometry yields an association constant of 21.7 M-1. Results also indicated that the cinnamic acid readily conformed to fit within the α-cyclodextrin host molecule, which remained a rigid structure. An 8.9% weight to weight of cinnamic acid was calculated for the solid inclusion again reinforcing a 2:1 stoichiometry. Microbiological studies showed little to no inhibition power by the complex at varying concentrations against S. cerevisiae and P. variotii. Free cinnamic acid showed greater antimicrobial activity compared with free α-cyclodextrin and the complex.
  • Thumbnail Image
    Characterization of Campylobacter, Salmonella, and Diarrheagenic Escherichia Coli from Food, Food Waste and Water in the Chobe Region of Botswana
    Bywater, Auja L. (Virginia Tech, 2023-06-23)
    Introduction and Justification: Diarrheal disease is a leading cause of death in children in low- and moderate-income countries. Food, food waste, and water are all vehicles that can promote the spread of diarrheal disease-causing bacteria like Campylobacter, Salmonella enterica, and E. coli. Resistance to commonly used antibiotics is on the rise, making them difficult to manage. This study aimed to determine prevalence and antibiotic resistance profiles of Campylobacter, S. enterica, and E. coli isolated from food, food waste, and water samples obtained from the Chobe Region of Botswana. In addition, the survival of two common pathogens, E. coli and C. jejuni, on kale, a type of leafy green commonly consumed raw, was determined. Methods: Samples were collected from the Chobe region of Botswana in 2022 including water from the local river, food (produce, beef, pork, and poultry) from local vendors, and food scraps from the landfill. Food samples were enriched in the appropriate selective media: Brilliant Green Bile Broth for E. coli, Bolton Broth for Campylobacter, and Rappaport Vassiliadis Broth for S. enterica. Water samples were collected using modified USEPA methods1103.1 and 1604, E.coli isolation was performed by plating on RAPID E.coli2 agar and incubation at 37°C for 2h and 44°C for 16-22h. Campylobacter, S. enterica, and E. coli were isolated from meat, poultry, and water samples before being sent to Virginia Tech, while enriched bacterial pellets from the produce were shipped for screening and isolation at Virginia Tech. E.coli were confirmed by PCR detecting the phoA gene (all E. coli), and classified as pathogenic through screening for the eae (present in enterohemorrhagic and enteropathogenic E.coli), stx1 and stx2 (present in enterohemorrhagic E. coli) and est1b ( present in Enterotoxigenic E.coli) genes. Campylobacter isolates were confirmed using a genera-specific PCR while S. enterica isolates were confirmed using invA primers. These enrichment and primer sets were tested as part of a study to determine the survival of E. coli O157:H7 and C. jejuni on kale during a 21-day shelf life. E. coli and S. enterica isolates were subjected to antibiotic resistance testing using the Kirby-Bauer Disk Diffusion method. Results: Methods for detection of inoculated E. coli O157:H7 on kale indicated survival for the majority of the shelf-life (up to 19 d), in comparison, C. jejuni was undetectable by day 13 using enrichment and PCR or plating. From the Botswanan samples, E. coli was isolated from 20% of produce, 49% of meat, and 84.7% of water. Salmonella was only isolated from produce samples (2.4%, 7/294). Resistance was uncommon among the Salmonella isolates with only one isolate being resistant to chloramphenicol. No Campylobacter were isolated from the screened produce, meat, or food waste. E. coli resistant to 3 or more classes of antibiotics (MCR) were identified in 15.5% of produce, and 22.2% of meat isolates. Isolation of E. coli or Salmonella from meat was not associated with a particular food type. In contrast, isolation of E. coli was more common from certain types of vegetables and fruits. Antibiotic-resistant E. coli were isolated more commonly from beef, poultry, and pork than from produce. Multi-class resistant E. coli were isolated from fruits, greens, soil associated, and above ground associated vegetables, beef, and poultry. Water samples were collected from the same time period as the food samples. E. coli isolation, especially pathogens (based on eae presence) was more frequent from environmental water samples collected during the wet season compared to the dry season. Water samples collected during periods of increased rainfall were more likely to contain E. coli isolates, especially pathogens. S. enterica and Diarrheagenic E. coli isolates, especially MCR isolates, pose a significant risk of illness to consumers. Strategies to reduce the circulation of these pathogens in foods and water sources are needed.  
  • Thumbnail Image
    Characterization of Clinical and Commensal Escherichia coli Isolates from an Integrated Turkey Operation
    Altekruse, Sean Fitzgerald (Virginia Tech, 2001-10-26)
    Pathogenic E. coli infections cause approximately one quarter of disease losses in commercial turkey flocks. A small subgroup of E. coli causes most infections. Epidemiologic studies of this disease have been hindered by a lack of reliable markers to discriminate between pathogenic and fecal E. coli and by the diversity of poultry strains. Reliance on antimicrobials to control E. coli infections has caused widespread antimicrobial resistance. One hundred five clinical E. coli were obtained, and 1104 isolates were collected from fecal specimens of 20 flocks in an integrated turkey operation. Biochemical fingerprinting and antimicrobial susceptibility tests were performed on all isolates, and somatic antigen serologic testing and PCR for potential virulence genes were conducted on 299 strains including all clinical isolates and fecal isolates that had similar traits to clinical isolates. Most avian E. coli infections were caused by a few clonal strains that were uncommon in normal fecal flora. The potential virulence genes iss, K1 and tsh were detected more frequently among clinical than fecal isolates; however, the pattern of occurrence did not suggest that these genes were useful markers for identifying pathogenic strains. Syndromes consistent with colibacillosis were the most commonly reported illness and principal rationale for antimicrobial therapy in sampled flocks. Most clinical E. coli isolates were resistant to gentamicin, sulfamethoxazole and tetracycline. Although resistance to fluoroquinolones and β-lactam antibiotics occurred less frequently, the potential for resistance to emerge to these antimicrobials was evident. A Bayesian model to estimate sample size confirmed the diversity of avian fecal E. coli strains. Studies are needed to define risk factors for infection with and identify markers for avian pathogenic E. coli strains. These research priorities are complementary and may lead to the identification of new interventions to prevent this important infectious disease of poultry.
  • Thumbnail Image
    Clostridium botulinum toxin development in refrigerated reduced oxygen packaged Atlantic croaker (Micropogonias undulatus)
    Rheinhart, Courtney Elizabeth (Virginia Tech, 2007-04-30)
    The purpose of this study was to determine the effects of storage temperature and film oxygen transmission rate (OTR) on toxin development by Clostridium botulinum in refrigerated raw vacuum packaged croaker fillets, and to determine if toxin development precedes microbiological and/or organoleptic spoilage. Raw croaker fillets were vacuum packaged in oxygen-permeable films (OTR of 10,000 cc/m2/24hr or 3,000 cc/m2/24hr) and stored at either 4ºC or 10ºC. Type 83F, 17 Type B, Beluga, Minnesota, and Alaska nonproteolytic strains of C. botulinum were used to inoculate fish prior to vacuum packaging. At both temperatures, microbial spoilage preceded toxin production in fillets vacuum packaged in both film types. At 4ºC microbial spoilage occurred after approximately 7 days for fillets vacuum packaged in the 10,000 cc/m2/24hr OTR film and after 8 days for fillets vacuum packaged in the 3,000 cc/m2/24hr OTR film. However, toxin was not detected until day 8. At 10ºC microbial spoilage occurred after approximately 3 days for fillets vacuum packaged in the 10,000 cc/m2/24hr OTR film, while toxin production occurred on day 5. For fillets vacuum packaged in the 3,000 cc/m2/24hr OTR film microbial spoilage occurred after 4 days. However toxin production did not occur until day 6. In contrast, at both temperatures toxin production preceded or coincided with organoleptic spoilage in fillets vacuum packaged in both film types. At 4ºC organoleptic spoilage occurred after 10 days for fillets packaged in the 10,000 cc/m2/24hr OTR film and after 9 days in the 3,000 cc/m2/24hr OTR film, while toxin production occurred on day 8. At 10ºC organoleptic spoilage occurred after 6 days for fillets packaged in the 10,000 cc/m2/24hr OTR film, and toxin was detected on day 5. For fillets packaged in the 3,000 cc/m2/24hr OTR film and stored at 10ºC, organoleptic spoilage occurred after 6 days, while toxin production occurred on day 6. Although toxin production preceded or coincided with organoleptic spoilage in both film types, this may have been because samples were presented on ice, which could have masked potential odors. This study shows that there are not significant differences between these film types when it comes to microbial and organoleptic spoilage. Therefore lower OTR films, such as 3,000 cc/m2/24hr film, may be used to vacuum package Atlantic croaker.
  • Thumbnail Image
    Cold Chain Management at Farmers’ Markets
    Acosta, Ernesto L. (Virginia Tech, 2023-01-16)
    Small farms are exempt from the Food Safety Modernization Act. Thus, educational materials are necessary to remind small farmers about safe food handling practices. The cold chain (refrigeration) is an important part of the farm to fork process. A guide about cold chain management is a useful reminder that can help reduce the risk of foodborne illness.
  • Thumbnail Image
    Consumer Knowledge of Fresh Produce Safety and the Food Safety Modernization Act
    Schrier, Stevie (Virginia Tech, 2014-05)
    Between 1976 and 2012, there has been an increase in fresh fruit consumption from around 31 kg. (68 lbs.) of fruit per capita to around 136 kg. (300 lbs.) per capita and consumption of fresh vegetables has increased from around 45 kg. (100 lbs.) per capita to around 181 kg. (400 lbs.) per capita (Tables 2 and 3) (Cook, 2013). Most of the fresh produce is consumed raw. In the United States there are approximately 48 million cases of food borne illnesses reported every year resulting in 3,000 deaths (USDA- FSIS, 2013), and according to the Centers for Disease Control and Prevention (CDC) between the years of 1998 and 2008 almost half of the food borne illnesses were from consuming fresh produce (CDC, 2014a). This paper reviews current programs to prevent food borne illnesses in produce, including Good Agricultural Practices and the Food Safety Modernization Act. A consumer survey was also delivered to adults in Louisa County, Iowa, to determine the extent of their awareness of safe produce handling, common pathogens found on produce, and legislation affecting the safety of produce.
  • Thumbnail Image
    Cooling Oysters to Within the New 10 Hour Required Time Frame from the Environment to 50 Fahrenheit or Below in a Refrigerated Storage Area
    Lane, Robert (Virginia Tech, 2011-07)
    A first encounter with the ruling that required Virginia original dealers of shellstock oysters destined for the half shell market to reduce the internal temperature to below 50 ⁰F within 10 hour of harvest was in reviewing a thermal model of a pallet of oysters bound for shipment. (Figure 1) The model was of a pallet of oyster boxes 48 x 40 x 60 inches tall, wrapped in plastic, as is the practice in shipment and placed in a blast freezer at -40⁰F. The model provided for temperature probes placed within the boxes at different parts of the pallet stack showed that the oyster internal temperatures did not achieve temperature below 50 ⁰F within the 10 hour time frame. (Figure 2) The model was then broken down into 48x40 x12 inches or equivalent of 1layer on a pallet, wrapped in plastic and placed in a blast freezer at – 40 ⁰F. The model again provided for temperature probes placed within the boxes however oyster internal temperature again did not achieve temperature below 50 ⁰F within the 10 hour time frame (Figure 3) (Conversation with Mike Jahncke Ph.D. Virginia Seafood AREC Director, June 1, 2010). A data logging apparatus was employed to test the capabilities of three major seafood companies to meet the new standard.
  • Thumbnail Image
    Cyberbiosecurity Importance in Relation to Small Fermentation Businesses and How to Integrate it into Known Hazard Planning Tools
    Knapp, Jordan; Strawn, Laura K.; Wiersema, Brian D.; Eifert, Joseph D.; Hamilton, Alexis M. (Virginia Tech, 2024-08-07)
    Cyberbiosecurity threats are on the rise in many various industries (Drape et al., 2021). With attacks on water treatment plants, medical facilities and more, awareness for what cyberbiosecurity is, what it looks like, and how to implement countermeasures into known hazard planning tools is dire. This project set out to address these issues in the context of small fermentation businesses. A survey was conducted but, due to low response rate, there was no statistical nor quantitative analysis performed on the survey results. The information gleaned from the survey was used to better guide how a factsheet would be created and used to gauge, what the fermentation community in North Carolina and Virginia was aware of in relation to food safety, the Food Safety and Modernization Act, and cyberbiosecurity. A factsheet was designed to guide small fermentation businesses on how to identify cyberbiosecurity is, what hazards exist, how to implement control measures into known hazard planning tools, and what methods exist to better protect their businesses.