Death of Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes in Shelf-Stable, Dairy-Based, Pourable Salad Dressings

摘要: The objectives of this study were to determine the death rates Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes in three commercially manufactured full-fat ranch salad dressings, reduced-fat two blue cheese dressings affirm expectation that these do not support growth pathogens. respective initial pH values four types shelf-stable, dairy-based, pourable 2.87 3.72, 2.82 3.19, 3.08 3.87, 2.83 3.49, respectively. Dressings inoculated with low (2.4 2.5 log CFU/g) high (5.3 5.9 populations separate five-strain mixtures each pathogen stored at 25 degrees C for up 15 days. Regardless inoculum population, all test pathogens rapidly died dressings. Salmonella was undetectable by enrichment (<1 CFU/25-ml sample replicate trials) within 1 day, E. O157:H7 L. reduced levels between 8 days 2 days, detected 4 10 or more 9 6 after inoculation. 3 but only one dressing, enrichment, indicating it had highest tolerance among acidic environment imposed Overall, type dressing (i.e., versus cheese) level fat did have a marked effect on rate inactivation Total counts lactic acid bacteria yeasts molds remained (<1.0 CFU/ml) throughout 15-day storage period. Based observations, companies should be considered as potentially hazardous foods (time-temperature control safety foods) defined U.S. Food Drug Administration Code.