The antimicrobial effect of thyme essential oil, nisin, and their combination against Listeria monocytogenes in minced beef during refrigerated storage.
The antimicrobial effect of thyme essential oil (EO) at 0.3%, 0.6%, or 0.9%, nisin at 500 or 1000IU/g, and their combination against Listeria monocytogenes was examined in both tryptic soy broth (TSB) and minced beef meat. Thyme EO at 0.3% possessed a weak antibacterial activity against the pathogen in TSB, whereas at 0.9% showed unacceptable organoleptic properties in minced meat. Thus, only the level of 0.6% of EO was further examined against the pathogen in minced meat. Treatment of minced beef meat with nisin at 500 or 1000IU/g showed antibacterial activity against L. monocytogenes, which was dependent on the concentration level of nisin and the strains used. Treatment of minced beef meat with EO at 0.6% showed stronger inhibitory activity against L. monocytogenes than treatment with nisin at 500 or 1000IU/g. All treatments showed stronger inhibitory activity against the pathogens at 10 degrees C than at 4 degrees C. The combined addition of EO at 0.6% and nisin at 500 or 1000IU/g showed a synergistic activity against the pathogen. Most efficient among treatments was the combination of EO at 0.6% with nisin at 1000IU/g, which decreased the population of L. monocytogenes below the official limit of the European Union recently set at 2logcfu/g, during storage at 4 degrees C.
Solomakos
N
N
Laboratory of Hygiene of Foods of Animal Origin, Faculty of Veterinary Medicine, University of Thessaly, 224 Trikalon Street, 43100 Karditsa, Greece.
Govaris
A
A
Koidis
P
P
Botsoglou
N
N
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D015169:Colony Count, Microbial; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D005519:Food Preservation / Q000379:methods*; D008089:Listeria monocytogenes / Q000187:drug effects* / Q000254:growth & development; D008461:Meat Products / Q000382:microbiology*; D009561:Nisin / Q000494:pharmacology*; D009822:Oils, Volatile / Q000494:pharmacology*; D013649:Taste; D013696:Temperature; D046930:Thymus Plant / Q000737:chemistry*; D013997:Time Factors
D000900:Anti-Bacterial Agents; D009822:Oils, Volatile; D009561:Nisin