Antibacterial Activity of the Lactoperoxidase System Against Salmonella typhimurium in Trypticase Soy Broth in the Presence and Absence of a Heat Treatment.

The antibacterial activity of the lactoperoxidase system (LP system) on the growth and survival of Salmonella typhimurium in tryptic soy broth (TSB) was determined. The LP system, consisting of lactoperoxidase (1 μg/ml), potassium thiocynante (KSCN) (5.9 mM) and HO (2.5 mM), was found to have both bacteriostatic and bactericidal activities against strains of S. typhimurium . The bactericidal activity was clearly dependent on the initial inoculum level. Levels of 10 - 10 CFU/ml were killed at 37°C as opposed to the bacteriostatic activity with inoculum levels of 10 - 10 CFU/ml, which exhibited a 25-h lag. The LP system also enhanced thermal inactivation of S. typhimurium . D-values were > 60 min (untreated broth) and 12 min (LP system activated); corresponding D-values were 20 min and 7.5 min; corresponding D-values were 14 min and 4 min; corresponding D -values were 5 min and 2.5 min and corresponding Devalues were .31 min and .20 min.