Effect of lactic acid bacteria starter culture, nisin, hydrogen peroxide, or potassium sorbate on Listeria monocytogenes, Staphylococcus aureus, and Salmonella typhimurium in white pickled cheese made from pasteurized milk with 4% salt and preserved in 4% brine solution at 4°C for 60 d was studied. The starter culture inhibited all three pathogens while antimicrobials did not. Beyond day 50 in curd and day 30 in brine solution, L. monocytogenes was not detected by direct plating in cheese with added starter culture. S. aureus was not detected after day 30 in curd and day 20 in brine solution in the same cheese. S. typhimurium was not detected after day 30 in cheese curd and was not detected in brine solution at any time with lactic acid bacteria starter culture added. The pH of brine solution of starter treatment dropped below 4.7 in all experiments, while antimicrobial treatments all had a pH >5.5.
1Present address: Institute of Animal Production, The University of Khartoum, Khartoum North, Sudan.
2Present address: Dept. of Food Science and Toxicology, Food Research Center, University of Idaho, Moscow, ID 83844-1053.