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Title:Using model miniature ham as a high-throughput tool to screen antimicrobials targeting l. Monocytogenes
Author(s):Rezac, Shannon Deborah
Advisor(s):Miller, Michael J; Stasiewicz, Matthew J
Department / Program:Food Science & Human Nutrition
Discipline:Food Science & Human Nutrition
Degree Granting Institution:University of Illinois at Urbana-Champaign
L. monocytogenes
Response Surface Methodology
Deli Meat
Abstract:The foodborne pathogen Listeria monocytogenes can be transmitted through eating contaminated foods, with outbreaks associated with ready-to-eat (RTE) products, such as deli ham, turkey, and hot dogs. Luncheon meats are often formulated with antimicrobial agents to limit the growth of this pathogenic microorganism. The present work develops methods to improve the current screening of antimicrobials for L. monocytogenes in deli ham. A miniature ham model was developed to minimize ham and antimicrobial use while utilizing common laboratory equipment. Growth of L. monocytogenes in the miniature ham model was compared to the traditional screening method of whole ham slices with and without an antimicrobial treatment and was confirmed to be not statistically different. An advanced statistical design, response surface methodology, was combined with the miniature ham model to efficiently screen antimicrobial treatments and combinations. Multiple Listeria spp. were utilized to screen four antimicrobials: nisin, potassium lactate sodium diacetate, lauric arginate, and bacteriophage Listex™ P100. The statistical design reduced the required amount of runs compared to traditional screening while identifying effective antimicrobial levels and antimicrobial combinations for all tested strains. In this model, nisin was identified as the most effective, regardless of the Listeria spp. Lastly, the miniature ham system was combined with a luminescence-based assay as a rapid and non-destructive preliminary screening tool. A luminescent L. monocytogenes strain was utilized to observe a correlation between traditional plate counts and light-emission from the ham surface. This was implemented into a screening of numerous antimicrobials by light-emission to distinguish between treatments that allowed a large amount of growth and treatments that did not, with cells numbers showing significant differences. Each of these models can be used to efficiently screen novel antimicrobials or compare between multiple ham formulations.
Issue Date:2019-07-16
Rights Information:Copyright 2019 Shannon Rezac
Date Available in IDEALS:2019-11-26
Date Deposited:2019-08

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