Your favourite cookies and cracker sandwiches could harbour harmful bacteria such as salmonella for as long as six months, scientists have found.
The study was prompted by an increased number of outbreaks of foodborne diseases linked to low-water-activity, or dry foods, researchers said.
"There have been an increased number of outbreaks of diseases associated with consumption of contaminated dry foods. We wouldn't expect salmonella to grow in foods that have a very dry environment," said Larry Beuchat, a researcher in the University of Georgia's College of Agricultural and Environmental Sciences, who led the study.
Beuchat and study co-author David Mann, found that not only can harmful bacteria survive in dry foods, like cookie and cracker sandwiches, but they can also live for long periods of time.
For the study, researchers used five different serotypes of salmonella that had been isolated from foods involved in previous foodborne outbreaks.
"Isolates were from foods with very low moisture content," Beuchat said.
Focusing on cookie and cracker sandwiches, the researchers put the salmonella into four types of fillings found in cookies or crackers and placed them into storage.
The researchers used cheese and peanut butter fillings for the cracker sandwiches and chocolate and vanilla fillings for the cookie sandwiches.
After storing, scientists determined how long salmonella was able to survive in each filling. There was survival in all types, Beuchat said, but salmonella survived longer in some types of the fillings than in others.
"The salmonella didn't survive as well in the cracker sandwiches as it did in the cookie sandwiches," Beuchat said.
In some cases, the pathogen was able to survive for at least to six months in the sandwiches.
As researchers learn about salmonella and other foodborne pathogens, they are "becoming aware that they can survive for unusual lengths of time in dry foods," Beuchat said.
The ability of pathogens to survive in some remarkable settings has researchers considering the next steps for preventing contamination and outbreaks they may cause.
"The next steps would be to test all ingredients that are used in these foods," Beuchat said.
If there is a possibility that foodborne pathogens are present in specific ingredients, then the next step would be to stop the use of those ingredients.
The study was published in the Journal of Food Protection.
