title: Behavior of Escherichia coli O157:H7 and Listeria monocytogenes during fermentation and storage of camel yogurt.
abstract: In addition to its nutritional and therapeutic properties, camel milk has the ability to suppress the growth of a wide range of foodborne pathogens, but there is a lack of information regarding the behavior of these pathogens in products such as yogurt produced from camel milk. The objective of the current study was to investigate the behavior of Listeria monocytogenes and Escherichia coli O157:H7 during manufacture and storage of camel yogurt. Camel milk inoculated with L. monocytogenes and E. coli O157:H7 was fermented at 43° C for 5h using freeze-dried lactic acid bacteria (LAB) starter cultures (Streptococcus thermophilus and Lactobacillus bulgaricus) and stored at 4 or 10 °C for 14 d. Camel milk inoculated with L. monocytogenes and E. coli O157:H7 without starter culture was also prepared. During fermentation, the numbers of L. monocytogenes and E. coli O157:H7 increased 0.3 and 1.6 log cfu/mL, respectively, in the presence of LAB, and by 0.3 and 2.7 log cfu/mL in the absence of LAB. During storage at 4 or 10 °C, L. monocytogenes increased 0.8 to 1.2 log cfu/mL by 14 d in camel milk without LAB, but in the presence of LAB, the numbers of L. monocytogenes were reduced by 1.2 to 1.7 log cfu/mL by 14 d. Further, E. coli O157:H7 numbers in camel milk were reduced by 3.4 to 3.5 log cfu/mL in the absence of LAB, but E. coli O157:H7 was not detected (6.3 log cfu/mL reduction) by 7d in camel yogurt made with LAB and stored at either temperature. Although camel milk contains high concentrations of natural antimicrobials, L. monocytogenes was able to tolerate these compounds in camel yogurt stored at refrigerator temperatures. Therefore, appropriate care should be taken during production of yogurt from camel milk to minimize the potential for postprocess contamination by this and other foodborne pathogens.
authors.affiliation: Department of Nutrition and Food Technology, Jordan University of Science and Technology, Irbid 22110, Jordan. Electronic address: anas_nabulsi@just.edu.jo.
authors.forename: Anas A
authors.initials: AA
authors.lastname: Al-Nabulsi
authors.affiliation: Department of Clinical Nutrition and Dietetics, Hashemite University, Zarqa 13133, Jordan.
authors.forename: Amin N
authors.initials: AN
authors.lastname: Olaimat
authors.affiliation: Department of Nutrition and Food Technology, Jordan University of Science and Technology, Irbid 22110, Jordan.
authors.forename: Tareq M
authors.initials: TM
authors.lastname: Osaili
authors.affiliation: Department of Food Science, United Arab Emirates University, Al-Ain 15551, United Arab Emirates.
authors.forename: Mutamed M
authors.initials: MM
authors.lastname: Ayyash
authors.affiliation: Department of Food Science, United Arab Emirates University, Al-Ain 15551, United Arab Emirates.
authors.forename: Aisha
authors.initials: A
authors.lastname: Abushelaibi
authors.affiliation: Department of Biological and Genetic Engineering, Jordan University of Science and Technology, Irbid 22110, Jordan.
authors.forename: Ziad W
authors.initials: ZW
authors.lastname: Jaradat
authors.affiliation: Department of Clinical Nutrition and Dietetics, University of Sharjah, Sharjah 27272, United Arab Emirates.
authors.forename: Reyad
authors.initials: R
authors.lastname: Shaker
authors.affiliation: Department of Nutrition and Food Technology, Jordan University of Science and Technology, Irbid 22110, Jordan.
authors.forename: Mahmoud
authors.initials: M
authors.lastname: Al-Taani
authors.affiliation: Department of Food Science, University of Manitoba, Winnipeg, MB, R3T 2N2 Canada.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Holley
mesh_terms: D000818:Animals; D002162:Camelus; D019453:Escherichia coli O157 / Q000254:growth & development*; D005285:Fermentation; D005516:Food Microbiology; D007777:Lactobacillaceae; D007778:Lactobacillus / Q000254:growth & development; D008089:Listeria monocytogenes / Q000254:growth & development*; D008892:Milk / Q000382:microbiology; D015014:Yogurt / Q000382:microbiology*
keywords: Escherichia coli O157:H7; Listeria monocytogenes; camel milk; lactic acid bacteria; yogurt