title: Recovery and Growth Potential of Listeria monocytogenes in Temperature Abused Milkshakes Prepared from Naturally Contaminated Ice Cream Linked to a Listeriosis Outbreak.
abstract: The recovery and growth potential of Listeria monocytogenes was evaluated in three flavors of milkshakes (vanilla, strawberry, and chocolate) that were prepared from naturally contaminated ice cream linked to a listeriosis outbreak in the U.S. in 2015, and were subsequently held at room temperature for 14 h. The average lag phase duration of L. monocytogenes was 9.05 h; the average generation time was 1.67 h; and the average population level increase per sample at 14 h was 1.14 log CFU/g. Milkshake flavors did not significantly affect these parameters. The average lag phase duration of L. monocytogenes in milkshakes with initial contamination levels ≤ 3 CFU/g (9.50 h) was significantly longer (P < 0.01) than that with initial contamination levels > 3 CFU/g (8.60 h). The results highlight the value of using samples that are contaminated with very low levels of L. monocytogenes for recovery and growth evaluations. The behavior of L. monocytogenes populations in milkshakes prepared from naturally contaminated ice cream linked to the listeriosis outbreak should be taken into account when performing risk based analysis using this outbreak as a case study.
authors.affiliation: Office of Regulatory Science, Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park MD, USA.
authors.forename: Yi
authors.initials: Y
authors.lastname: Chen
authors.affiliation: College of Life Sciences and Agriculture, University of New Hampshire, Durham NH, USA.
authors.forename: Emma
authors.initials: E
authors.lastname: Allard
authors.affiliation: Joint Institute for Food Safety and Applied Nutrition, University of Maryland, College Park MD, USA.
authors.forename: Anna
authors.initials: A
authors.lastname: Wooten
authors.affiliation: Department of Food Science, Gachon University Seoul, South Korea.
authors.forename: Minji
authors.initials: M
authors.lastname: Hur
authors.affiliation: Office of Regulatory Science, Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park MD, USA.
authors.forename: Ishani
authors.initials: I
authors.lastname: Sheth
authors.affiliation: Office of Regulatory Science, Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park MD, USA.
authors.forename: Anna
authors.initials: A
authors.lastname: Laasri
authors.affiliation: Office of Regulatory Science, Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park MD, USA.
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Hammack
authors.affiliation: Office of Regulatory Science, Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park MD, USA.
authors.forename: Dumitru
authors.initials: D
authors.lastname: Macarisin
keywords: L. monocytogenes; growth potential; ice cream; milkshake; outbreak; temperature abuse