Nitrite-induced injury of Listeria monocytogenes and the effect of selective versus nonselective recovery procedures on its isolation from frankfurters.
Sodium nitrite (NaNO2) is used as a curing agent in frankfurters. Although previous studies have documented the bacteriostatic abilities of NaNO2 toward Listeria monocytogenes, few if any studies have been conducted that consider the possibility of sublethal injury to L. monocytogenes by exposure to NaNO2. The goals of this study were to determine whether NaNO2 has the ability to injure L. monocytogenes, to determine whether nitrite injury is reversible, and to compare the recovery of L. monocytogenes from frankfurters containing nitrite with Listeria repair broth (LRB) and University of Vermont modified Listeria enrichment broth (UVM). NaNO2, when used at concentrations of 100 and 200 ppm, was found to injure L. monocytogenes. The injury was completely reversible, or growth of uninjured Listeria occurred in LRB when injury was between 98.5 and 98.7%. However, total recovery was not observed in LRB when injury exceeded 99%. UVM was unable to reverse the effects of nitrite-injured L. monocytogenes. With respect to time, inoculum, and meat type, LRB was found to be consistently superior to UVM at recovering L. monocytogenes from frankfurters. Nitrite injury might be a factor influencing detection and recovery of L. monocytogenes from frankfurters.
Ngutter
Crystal
C
Department of Nutrition and Food Sciences, University of Vermont, Burlington, Vermont 05405-0148, USA.
Donnelly
Catherine
C
D015169:Colony Count, Microbial; D003470:Culture Media / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D005516:Food Microbiology; D005519:Food Preservation / Q000379:methods; D005520:Food Preservatives / Q000494:pharmacology*; D008089:Listeria monocytogenes / Q000187:drug effects* / Q000254:growth & development; D008461:Meat Products / Q000382:microbiology*; D012977:Sodium Nitrite / Q000494:pharmacology*
D003470:Culture Media; D005520:Food Preservatives; D012977:Sodium Nitrite