Inhibition and Inactivation of Listeria monocytogenes by Sorbic Acid

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Abstract
Inhibition and inactivation of Listeria monocytogenes by sorbic acid were studied using tryptose broth supplemented with 0, 0.05, 0.1, 0.15, 0.2, 0.25 or 0.3% potassium sorbate; adjusted to pH 5.6 or 5.0; and incubated at 4, 13, 21 or 35°C. The bacterium grew in sorbate-free controls under all conditions except at 4°C and pH 5.0. At pH 5.6 and 4°C, the bacterium was inactivated by 0.25 or 0.3% of potassium sorbate after 66 and 60 d. Other concentrations permitted slight growth followed by decreases in populations. At 4°C and pH 5.0, concentrations of 0.15 to 0.3% potassium sorbate completely inactivated the pathogen in 60 to 36 d, whereas the other concentrations caused a gradual decrease in populations during the incubation period. At 13°C and pH 5.6, L. monocytogenes grew at all test concentrations of potassium sorbate, but the maximum populations were directly related to the concentration of potassium sorbate added to the medium - the higher the concentration, the lower the ultimate maximum population....