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Browsing by Author "Thompson, Tyler Warren, author"

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    A comprehensive study of Salmonella infections and microbial analysis of probiotics on beef cattle
    (Colorado State University. Libraries, 2023) Thompson, Tyler Warren, author; Nair, Mahesh Narayanan, advisor; Geornaras, Ifigenia, committee member; Belk, Keith, committee member; Noyes, Noelle, committee member; Morley, Paul, committee member
    Non-typhoidal Salmonella remains a significant concern for food safety in the United States, causing millions of infections, hospitalizations, and deaths yearly. The Healthy People 2030 initiative set forth by the U.S. Department of Health and Human Services aims to address this issue by establishing goals and objectives for national health promotion and disease prevention, including two objectives focused on Salmonella control in the food supply. The recent declaration of Salmonella as an adulterant in certain poultry products by the U.S. Department of Agriculture further highlights the urgency of this issue. To align with the Healthy People 2030 goals and achieve a 25% reduction in salmonellosis, the U.S. Department of Agriculture's Food Safety and Inspection Service (FSIS) implemented new performance standards for beef products. However, such policies must be supported by quantitative microbial risk assessments (QMRA) to determine their impact on Salmonella infections. Therefore, these analyses would benefit from a systematic review examining existing literature on Salmonella, considering factors such as illness rates, exposure, and bacterial loads. This review included 42 articles that provided data necessary for fitting a dose-response model to empirical data that describes how dose, virulence group, and food vector affect illness (attack) rates. Results from the mixed-effects logistic regression model showed significant impacts of log dose consumed, virulence group, and food vector on illness rates. Notably, Salmonella serogroups of "Higher" virulence were found to be associated with greater odds of illness than "Lower" virulence strains. The study highlights the need for improved data reporting and standardized outbreak investigations to enhance the fitting of models to outbreak data. By considering factors like serovar group and food vector in the modeling process, regulators can demonstrate what influences attack rate to frame more effective food safety policies. In conclusion, this systematic review provides valuable insights into Salmonella infection risk from food sources and emphasizes the importance of evidence-based policies to reduce the burden of Salmonella-related illnesses and improve food safety in the United States. Liver abscesses in beef cattle are a common problem associated with highly-fermentable carbohydrate diets during finishing, leading to decreased production efficiency and aggregate carcass value. Dietary antimicrobial supplementation, such as tylosin, helps to control liver abscesses but raises concerns about selection for antimicrobial resistance. This study examined the impact of a probiotic mixture of propionic and lactic acid bacteria on microbial communities and antimicrobial resistance genes (ARGs) in fecal and liver abscess samples from beef cattle alongside Salmonella populations of mesenteric lymphatic tissues. Treatment diets fed in this study included a probiotic mixture alone (DFM), inclusion of Tylosin (TYL), a combination of including both (DFM+TYL), and a control group diet that did not include any supplements (CON). Fecal samples were collected at the time that feeding started, and then 28 d before arriving at the abattoir, where liver abscesses and mesenteric lymph nodes were sampled. Fecal and liver abscess samples were subjected to 16S rRNA and targeted enriched shotgun metagenomics to evaluate microbial communities and resistance genes of bacteria present. A portion of the liver abscess and mesenteric lymph nodes were tested for presence of Salmonella using PCR with further analysis of enumeration and serotype classification for mesenteric lymph nodes. Results showed no differences (P > 0.05) between the fecal microbiomes of the different treatment groups, and the addition of tylosin or probiotic mixture did not impact the fecal resistome. Similarly, no differences (P > 0.05) were observed between the liver abscess microbiomes of the different (P > 0.05) treatment groups, with Fusobacteria and Bacteroidetes being the dominant phyla in liver abscesses. Results indicated that incorporating DFMs did not affect Salmonella prevalence in the cattle's mesenteric lymph nodes or liver abscesses. Presence of Salmonella was found at low levels in only 22% of samples (91 positive out of 503 samples), just below 1 log CFU/g, and was predominantly represented by the C1 serogroup in mesenteric lymph nodes. These findings suggest that while diet interventions may not have a substantial impact, Salmonella can colonize mesenteric lymphatic tissues in cattle at low frequencies and concentrations. Treatment groups tested had no impact (P > 0.05) on fecal and liver abscesses microbiomes and resistance gene presence, along with no impact on Salmonella prevalence in liver abscesses or mesenteric lymphatic tissues.
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    Quality and nutritional aspects of conventional and novel food proteins
    (Colorado State University. Libraries, 2020) Thompson, Tyler Warren, author; Nair, Mahesh Narayanan, advisor; Belk, Keith E., advisor; Geornaras, Ifigenia, committee member; Weir, Tiffany, committee member
    Cattle weights have increased during the last couple of decades and have not always been accompanied by improvements in facility capabilities and management. Alongside quality issues of color, tenderness, and water holding capacity, issues such as sour muscles and bone taints are now appearing with high frequency in the meat industry. Development of off-flavor/sourness in deep muscles such as knuckles (vastus femoris, vastus lateralis, vastus medialis, and rectus femoris) has been a long-standing issue in the beef industry, however, has not been well characterized. Therefore, the objective of this study was to investigate the potential cause and to characterize the sour odor associated with beef knuckles using microbial, odor panel, and gas chromatography-mass spectrometric (GC-MS) analyses. Knuckles (n = 10) identified as having no sour odor (control), slight sour odor (SLI-SO), or severe sour odor (SVR-SO) were collected from the fabrication line of a commercial beef processing plant. Upon collection of knuckles, synovial fluid and the femur surface were swabbed to determine psychrotrophic anaerobic sporeformer presence. The collected knuckles were transported on ice to the laboratory where they were aseptically separated into two halves, with one half destined for microbial, odor, and GC-MS analyses on the day of collection (day 0) and the other half for the same analyses (excluding GC-MS) after 35 days of vacuum packaged storage at 0 - 2°C (day 35). For microbial analysis, 15 g of tissue was excised from the muscle surface and was analyzed for aerobic plate counts (Petrifilm Aerobic Count plates) and lactic acid bacteria counts (Lactobacilli MRS agar). Samples (5 g) for GC-MS were held at -80°C until analysis. The remainder of the sample was diced and used for trained odor panels. Odor panelists identified differences (P < 0.05) for all tested attributes (off odor, oxidation, putrid, and sour notes) between control and sour knuckles (SLI-SO and SVR-SO) on day 0. Similarly, on day 35, differences (P < 0.05) were observed between control, SLI-SO, and SVR-SO knuckles for all attributes, with SVR-SO samples receiving the highest score for all categories. However, the microbiological analysis found no differences between aerobic plate counts and lactic acid bacteria counts of control, SLI-SO, and SVR-SO knuckles on day 0 or day 35. In addition, GC-MS analysis did not indicate a difference (P > 0.05) in the abundance of volatiles between the treatments (probably due to high variations within treatment groups). Overall, compounds such as acetic, acetoin, propionic, butyric, and isobutyric acid were trending towards having greater abundance in sour samples. Although animal proteins have been the primary source of protein in the human diet, plant-based proteins have gained popularity in recent years. While some studies have indicated lesser environmental impacts, the nutritional composition of plant-proteins has not been readily investigated. Therefore, the objectives were to evaluate the nutritional composition of Morning Star Farms spicy black bean burger (VB), Beyond Meat's Beyond Burger (BB), Impossible Food's Impossible Burger (IB), a boneless top loin pork chop (PC), and 80% lean 20% fat ground pork (GP). Six different cities were selected for product collection to give a representative view of the products (Seattle, WA; Peyton, CO; Memphis, TN; Newburgh, IN; Houston, TX; and Brooklyn, NY). Following collection, products were brought back to Colorado State University. Half of the products sampled from each city were cooked, and the remaining half were left in their raw state. All ground products were cooked to an internal temperature of 71°C while the PC was cooked to 63°C. Samples (both raw and cooked) were then homogenized individually and stored under vacuum-packaged conditions at -80°C until further analysis. Methodologies for proximate analysis, amino acids, fatty acids, minerals, vitamins, organic acids, and allergens were conducted following the Association of Official Analytical Chemist (AOAC) guidelines. Overall, the product state (raw or cooked) had little effect on the nutritional composition. Analysis indicated that the PC contained the highest (P < 0.05) amounts of protein, essential amino acids, and B-vitamins. Cholesterol was found highest (P < 0.05) in the pork products (PC and GP) with no cholesterol being identified in the plant-based products (VB, BB, and IB). However, when evaluating mineral make-up, the plant-based products contained the highest (P < 0.05) amounts, especially in sodium and iron levels. Sodium levels were about ten times higher, along with iron levels being 3 to 4 times higher in plant-based products. Overall, the pork products were found to contain the greatest amounts of amino acids, and B-vitamins needed in a diet. While the plant-based products were generally lower in nutrients, the IB was found at nutritional levels close to the GP and PC.