Antibacterial activity of carvacrol, citral, and geraniol against Salmonella typhimurium in culture medium and on fish cubes

Carvacrol, citral and geraniol showed potent antibacterial activity against Salmonella typhimurium and its rifampicin-resistant (Rif(R)) strain as determined in tryptic soy broth and by zone of inhibition on agar-based medium. Carvacrol had the most potent bactericidal activity, with minimum inhibitory and bactericidal concentrations (MIC and MBC) of 250 mu g/mL for both tester strains. When tested at 0.5, 1.5 and 3.0% in 1% Tween 20 for bactericidal activity against Rif(R)-S. typhimurium inoculated on fish cubes, carvacrol at 3.0% completely killed the inoculated bacteria, while geraniol killed most of the bacteria, and citral killed the least. Carvacrol and geraniol showed potent antibacterial activity at 1.5%. Bactericidal activity became more evident as storage of fish cubes at 4 degrees C lengthened. The comparable inhibition of these strains of Salmonella and species of Gram-negative bacteria by carvacrol and geraniol support their application as potential antibacterial agents in food systems.