Acidic conditions encountered during the digestive process may not be enough to inactivate some harmful bacteria in fermented dry sausages say Canadian researchers. Their findings appear in the November 2004 issue of the journal Applied and Environmental Microbiology.
Escherichia coli O157:H7 is one of the leading causes of foodborne diseases and can result in severe complications in humans ranging from hemorrhagic colitis to death. Previous outbreaks have been primarily associated with ground beef and raw milk, but a recent increase in cases involving highly acidic foods such as fermented dry sausages, mayonnaise, and apple cider have raised new concerns.
In the study fermented dry sausages were inoculated with E. coli O157:H7 and exposed to synthetic saliva for 1 minute, synthetic gastric juice for 120 minutes, and synthetic pancreatic juice for 250 minutes. Results showed that not only did existing E. coli O157:H7 cells remain viable after exposure to both synthetic saliva and gastric juice, they began to grow at a significant rate when exposed to the pancreatic juice.
"From a food safety point of view, this implies that the industrial processes used to manufacture dry sausages must be designed in such a way that no viable E. coli O157:H7 cell can ever be found in an average portion of sausage for human consumption, because no additional protection will be afforded by the subsequent digestive process," say the researchers. "This new information will be very valuable in refining our assessment of the risk associated with the manufacture of fermented dry sausages with regard to E. coli O157:H7."
(F. Naim, S. Messier, L. Saucier, G. Piette. 2004. Postprocessing in vitro digestion challenge to evaluate survival of Escherichia coli O157:H7 in fermented dry sausages. Applied and Environmental Microbiology, 70. 11: 6637-6642.)