TABLE 4

Log reduction of L. monocytogenes Scott A treated with EOCs mixed via an end-to-end shaker or an ethanol stock solution in skim milk at 21°C

CompoundOverall concnLog reductiona
End-to-end shaker95% (vol/vol) ethanol
0 h24 h0 h24 h
Thymol5 g/liter>5.3 ± 0.2 a>5.3 ± 0.2 a>5.3 ± 0.2 a>5.3 ± 0.2 a
2.5 g/liter0.3 ± 0.5 b>5.3 ± 0.2 a>5.3 ± 0.2 a>5.3 ± 0.2 a
Carvacrol5 g/liter>5.3 ± 0.2 a>5.3 ± 0.2 a>5.3 ± 0.2 a>5.3 ± 0.2 a
2.5 g/liter>5.3 ± 0.2 a>5.3 ± 0.2 a>5.3 ± 0.2 a>5.3 ± 0.2 a
trans-Cinnamaldehyde9 g/liter0.2 ± 0.3 c1.3 ± 0.5 b0.4 ± 0.5 c>5.3 ± 0.2 a
4.5 g/liter0.1 ± 0.2 c0.8 ± 0.2 b0.1 ± 0.4 b5.0 ± 0.7 a
Eugenol7 g/liter>5.3 ± 0.2 a4.2 ± 0.8 b>5.3 ± 0.2 a>5.3 ± 0.2 a
3.5 g/liter0.3 ± 0.3 c2.8 ± 0.4 b4.7 ± 1.3 a>5.3 ± 0.2 a
Controls
    Negative control (no antimicrobial)−2.1 ± 0.1 C
    Ethanol4.75% (vol/vol)0.1 ± 0.2 b−1.2 ± 0.1 a A
3.5% (vol/vol)0.1 ± 0.2 b−1.6 ± 0.2 a B
  • a The log reduction is the difference between the population of L. monocytogenes in the negative control at time zero and that after mixing with EOCs using an end-to-end shaker for 30 min or a stock solution in 95% ethanol using brief vortexing before (0 h) or after incubation at 21°C for 24 h. The population of L. monocytogenes in the negative control at 0 h was 6.2 ± 0.5 log CFU/ml. The numbers are means ± standard errors (n = 3). The detection limit was 1 log CFU/ml. Different lowercase letters next to the numbers in the same row and uppercase letters next to the controls in the same column represent significant differences (P < 0.05).