The minimum inhibitory concentration and mode of action of decanol against Listeria monocytogenes and its antilisterial effects in ready-to-eat meat products

The Minimum Inhibitory Concentration (MIC) of decanol was determined for six strains of Listeria monocytogenes (LM). The antibacterial effect of decanol in Muller Hinton Broth was determined spectrophotometrically following incubation for 60 hours. Generally, greater than or equal to 20-ppm decanol concentrations significantly inhibited the growth of all LM strains compared to control samples (P < 0.05). To evaluate the ability of decanol to affect the antilisterial activity of nisin in broth cultures, nisin concentrations of ≥ 400 IU in combination with 20-ppm decanol showed significant population reductions of LM following 24 hrs of incubation compared to a control sample (P < 0.05). Treatments containing decanol concentrations of ≤20-ppm and 50 IU nisin were also examined, and the results showed a significant inhibitory effect on total LM population for most of LM tested (P < 0.05).; The stress response of LM Scott A to decanol was examined with LIVE/DEAD BacLight fluorescence confocal microscopy. Red dyed cells were abundant following a one hour inoculation and represented the severely injured and dead cells. Also, SDS-PAGE was performed to examine the protein profile of LM Scott A exposed to decanol. Bands with molecular weight ≤ 45 showed differences between treatments and the control following 12 hours of exposure to decanol.; The antilisterial effectiveness of decanol was determined for two bologna types and sliced country ham stored at 4°C or 10°C for up to eighty days. Decanol concentration of 5% was effective at reducing the Listeria monocytogenes population three log units (P < 0.05). The synergistic effect of decanol and curing agents in commercial bologna had a significant effect on the LM population compared to the control sample (5 log reduction) (P < 0.05). The combination of decanol and sodium salt in country ham inhibited the LM population and resulting in two log reduction These results indicate that decanol is effective in reducing LM populations in broth cultures and also if combined with other treatments to control LM in meat products.