Beware! Cookies can kill
Researchers at the University of Georgia (UGA) were prompted to investigate salmonella in low-water-activity – or dry – foods because of an increased number of outbreaks of foodborne diseases.
Larry Beuchat, of the UGA College of Agricultural and Environmental Sciences, led a study to see how long bacteria that cause foodborne illness can survive in certain foods.
Salmonella is a bacteria that causes diarrhea, fever and abdominal cramps 12-72 hours after infection. Discovered by an American scientist, Dr. Salmon, it has been known to cause illness for over 125 years.
Salmonella infection usually passes after 4-7 days without treatment, but more serious cases can occur, involving severe diarrhea, a spread of infection from the intestines to the blood stream, and then to other body sites and sometimes death.
In severe cases, hospitalisation and prompt treatment with antibiotics are needed to bring the infection under control. The elderly, infants and those with impaired immune systems are more likely to be severely affected.
It was not expected that salmonella would grow in foods with a very dry environment.
Researchers used five different serotypes of salmonella that had been isolated from foods with very low moisture content, specifically cookie and cracker sandwiches that had been involved in previous foodborne outbreaks.
Alas! Salmonella survived at least 6 months in dry environment.
The investigators put the salmonella into four types of fillings found in cookies or crackers and placed them into storage.
They used cheese and peanut butter fillings for the cracker sandwiches and chocolate and vanilla fillings for the cookie sandwiches, to make the kind of product that is found in grocery stores or vending machines.
After storing, the scientists determined how long salmonella was able to survive in each filling.
The salmonella survived longer in some fillings than in others. The pathogen survived better in the cookie sandwiches than in the crackers, and in some cases, it survived for at least 6 months.
Beuchat and study co-author David Mann were surprised to find that the salmonella survived in the cookie environment and that it survived for so long.
The study adds to a growing body of evidence that salmonella and other foodborne pathogens can survive for unusual lengths of time in dry foods, say the researchers.
As a result of the findings, researchers are considering new measures for preventing contamination and outbreaks.
Beuchat says: “The next steps would be to test all ingredients that are used in these foods.”
He suggests that if there is a possibility of foodborne pathogens being present in specific ingredients, the use of those ingredients should be stopped. Measures should also be taken to ensure that contamination does not occur during manufacture.
Common sources of salmonella include food and water contaminated with small amounts of animal feces. Foods of animal origin, such as beef, poultry, milk, fish or eggs are most prone to contamination; but any food, including vegetables, fruits and processed foods can carry the bacteria.
Salmonella is estimated to cause one million cases of foodborne disease a year in the US; 19,000 hospitalisations occur due to salmonella each year and 380 Americans die each year from salmonella poisoning.
Contamination can occur in stores or in the kitchen, when drippings from raw meat or poultry contaminate surfaces and other foods in the refrigerator or in a shopping cart.
Using a cutting board and knife to prepare raw meat or poultry without washing them thoroughly between uses increases the risk. Contaminated foods usually look and smell normal.
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