Title page for ETD etd-05272004-181730


Type of Document Master's Thesis
Author Meadows, Bridget Archibald
Author's Email Address barchiba@vt.edu
URN etd-05272004-181730
Title Survival of Listeria monocytogenes, Listeria innocua, and Lactic acid bacteria species in chill brine
Degree Master of Science
Department Food Science and Technology
Advisory Committee
Advisor Name Title
Sumner, Susan S. Committee Chair
Eifert, Joseph D. Committee Member
Williams, Robert C. Committee Member
Keywords
  • Listeria monocytogenes
  • Listeria innocua
  • lactic acid bacteria
  • brine
Date of Defense 2004-05-11
Availability unrestricted
Abstract
SURVIVAL OF LISTERIA MONOCYTOGENES, LISTERIA INNOCUA,

AND LACTIC ACID BACTERIA SPECIES IN CHILL BRINES

Bridget Archibald Meadows

(ABSTRACT)

Listeria monocytogenes is the major pathogen in ready-to-eat meat products such as deli meats and frankfurters. Contamination can occur via the salt brines that are used to cool thermally processed meats. Both L. monocytogenes and lactic acid bacteria can grow and thrive under these brine conditions, and may become competitive with each other for available nutrients. The objective of this study was to determine the effect of a three strain cocktail of lactic acid bacteria Enterococcus faecalis, Carnobacterium gallinarum, and Lactobacillus plantarum on the survival of Listeria monocytogenes and Listeria innocua in brines stored under low temperatures up to 10 days. Three brine concentrations (0%, 7.9%, and 13.2% NaCl) were inoculated with ~7.0 log10 cfu/ml of one of five cocktails (L. monocytogenes, L. innocua, lactic acid bacteria (LAB), L. monocytogenes + LAB, or L. innocua + LAB) and stored for 10 days at either 4°C or 12°C. Three replications of each brine/cocktail/temperature combination were performed. No reductions of L. monocytogenes were seen in 7.9 or 13.2% NaCl with LAB; however, reductions of L. monocytogenes were seen in the 0% NaCl with LAB (1.43 log at 4°C and 3.02 log at 12°C). Listeria innocua was significantly less resilient to environmental stresses than L. monocytogenes, both with and without LAB present (p<0.05). This research indicates these strains of lactic acid bacteria are not effective at reducing L. monocytogenes in brines at low temperatures. Furthermore, the use of L. innocua as a model for L. monocytogenes is not appropriate under these environmental conditions.

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 28.8 Modem   56K Modem   ISDN (64 Kb)   ISDN (128 Kb)   Higher-speed Access 
  APPENDICES.pdf 65.94 Kb 00:00:18 00:00:09 00:00:08 00:00:04 < 00:00:01
  coverpages2.pdf 20.64 Kb 00:00:05 00:00:02 00:00:02 00:00:01 < 00:00:01
  p.1-49.pdf 287.25 Kb 00:01:19 00:00:41 00:00:35 00:00:17 00:00:01
  RESULTS.pdf 109.09 Kb 00:00:30 00:00:15 00:00:13 00:00:06 < 00:00:01

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