Efficacy of disinfectants to reduce Listeria monocytogenes on precut iceberg lettuce.
The efficacy of water, chlorinated water (100 ppm), peracetic acid solution (0.05%), and commercial citric acid-based produce wash (0.25%) to reduce the population of Listeria monocytogenes on precut lettuce was tested. Samples were inoculated with a mixture of equal amounts of five L. monocytogenes strains at a level of 4.7 log CFU/g, and analyzed on the day of washing and after 3 and 6 days of storage at 6 degrees C. Sanitizer reduced the number of L. monocytogenes at maximum 1.7 log CFU/g and number of L. monocytogenes reached the inoculation level during 6 days of storage. Thus, disinfectants do not eliminate L. monocytogenes on precut lettuce and cannot be solely relied on in producing precut lettuce safely. The inoculated L. monocytogenes strains were recovered at different rates after 6 days of storage; one of these strains was not recovered at all. Thus, strain-specific differences exist in the ability of L. monocytogenes to survive the washing treatments of the lettuce.
Hellström
Sanna
S
Department of Food and Environmental Hygiene, Faculty of Veterinary Medicine, University of Helsinki, Finland. sanna.hellstrom@helsinki.fi
Kervinen
Riitta
R
Lyly
Marika
M
Ahvenainen-Rantala
Raija
R
Korkeala
Hannu
H
D002713:Chlorine / Q000494:pharmacology; D019343:Citric Acid / Q000494:pharmacology; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D004202:Disinfectants / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005511:Food Handling / Q000379:methods*; D005516:Food Microbiology; D006801:Humans; D018545:Lactuca / Q000382:microbiology*; D008089:Listeria monocytogenes / Q000187:drug effects* / Q000254:growth & development; D010463:Peracetic Acid / Q000494:pharmacology; D013696:Temperature; D013997:Time Factors
D004202:Disinfectants; D019343:Citric Acid; D002713:Chlorine; D010463:Peracetic Acid