Effect of Preservatives on Growth and Filamentation of Listeria monocytogenes on Ready-to-Eat Meats

• Author / Creator

  Willis, Devon B.

• Listeria monocytogenes is a foodborne pathogen known to contaminate RTE foods and grow at refrigeration temperatures. It is also known to form filaments when stressed, which may affect enumeration and compromise consumer safety. The objective of this study was to observe the growth and morphological changes in L. monocytogenes on RTE hams with multiple preservative treatments and stored at refrigeration temperatures.Two strains were inoculated onto hams formulated with sodium lactate (1.4% w/w) and sodium diacetate (0.1% w/w), chitosan (0.5% v/w added as a solution in 1% acetic acid), partially purified bacteriocins (25.6 activity units/g) from Carnobacterium maltaromaticum UAL307, and combinations of sodium lactate and sodium diacetate with chitosan or the partially purified bacteriocins. Inoculated hams were stored at 4°C for up to 120 d. Growth characteristics were determined by plating on PALCAM agar, while filamentation was assessed by imaging flow cytometry.A combination of sodium lactate and sodium diacetate with bacteriocins caused a significant decrease in the growth of L. monocytogenes on the hams compared to the other antimicrobial treatments. Imaging flow cytometry found that the proportion of the bacterial population that filamented was significantly lower on hams formulated with chitosan, either with or without bacteriocins present.These results show that different preservatives have different effects on the growth and cell morphology of L. monocytogenes, which may affect how these preservatives are applied and how this pathogen is regulated on RTE foods.

• Subjects / Keywords

  • preservative
  • ready-to-eat
  • chitosan
  • sodium lactate
  • filamentation
  • sodium dictate
  • ham
  • Listeria monocytogenes
  • bacteriocin

• Graduation date

  Fall 2020

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-7tvm-bh81

• License

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