Comparative survival of Salmonella typhimurium DT 104, Listeria monocytogenes, and Escherichia coli O157:H7 in preservative-free apple cider and simulated gastric fluid.
This study compared the survival of three-strain mixtures (ca. 10(7) CFU ml(-1) each) of Salmonella typhimurium DT104, Listeria monocytogenes, and Escherichia coli O157:H7 in pasteurized and unpasteurized preservative-free apple cider (pH 3.3-3.5) during storage at 4 and 10 degrees C for up to 21 days. S. typhimurium DT104 populations decreased by <4.5 log10 CFU ml(-1) during 14 days storage at 4 and 10 degrees C in pasteurized cider, and by > or =5.5 log10 CFU ml(-1) during 14 days in unpasteurized cider stored at these temperatures. However, after 7 days at 4 degrees C, the S. typhimurium DT104 populations had decreased by only about 2.5 log10 CFU ml(-1) in both pasteurized and unpasteurized cider. Listeria monocytogenes populations decreased below the plating detection limit (10 CFU ml(-1)) within 2 days under all conditions tested. Survival of E. coli O157:H7 was similar to that of S. typhimurium DT104 in pasteurized cider at both 4 and 10 degrees C over the 21-days storage period, but E. coli O157:H7 survived better (ca. 5.0 log10 CFU ml(-1) decrease) than S. typhimurium DT104 (> 7.0 log10 CFU ml(-1) decrease) after 14 days at 4 degrees C in unpasteurized cider. In related experiments, when incubated in simulated gastric fluid (pH 1.5) at 37 degrees C, S. typhimurium DT104 and L. monocytogenes were eliminated (5.5-6.0 log10 CFU ml(-1) decrease) within 5 and 30 min, respectively, whereas E. coli O157:H7 concentrations decreased only 1.60-2.80 log10 CFU ml(-1) within 2 h.
Roering
A M
AM
Department of Food Microbiology and Toxicology, Food Research Institute, University of Wisconsin-Madison, 53706-1565, USA.
Luchansky
J B
JB
Ihnot
A M
AM
Ansay
S E
SE
Kaspar
C W
CW
Ingham
S C
SC
D001628:Beverages / Q000382:microbiology*; D015169:Colony Count, Microbial; D019453:Escherichia coli O157 / Q000254:growth & development*; D005516:Food Microbiology; D005520:Food Preservatives; D005750:Gastric Juice / Q000382:microbiology; D006863:Hydrogen-Ion Concentration; D008089:Listeria monocytogenes / Q000254:growth & development*; D012034:Refrigeration; D019685:Rosales / Q000382:microbiology; D012486:Salmonella typhimurium / Q000254:growth & development*
D005520:Food Preservatives