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 5 h 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 7 d 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