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Nov 26, 2008 10:57 pm US/Central
Good Question: Does The '5-Second Rule' Work?
(WCCO)
Just about all of us have invoked the "five-second rule." It's the theory that you can drop a piece of food on the floor for up to five seconds before the food becomes too disgusting to eat. But does the five-second rule work?
"The answer is no," according to Francisco Diez, Ph.D., an Assistant Professor of Food Safety Microbiology at the University of Minnesota. "The five-second rule is pretty much an urban legend."
There hasn't been a large amount of research into this. In 2003, a high-school intern at the University of Illinois took the first step, finding that 70 percent of women she surveyed were familiar with the five-second rule.
In 2007, researchers at Clemson University tested floor-to-food contamination, using salmonella on tile, wood panels and carpeting. Then they dropped food on the bacteria.
The first step was finding out how long bacteria survives on those surfaces. Some survived for 28 days.
Next, they tested the five-second theory. They found that slices of bologna and bread left for five seconds gathered between 150 and 8,000 bacteria. After one minute, slices collected about 10 times more than that from the tile and carpet.
So picking it up quickly does mean you end up with fewer bacteria, but you can get sick by ingesting as few as 10 bacteria for some salmonella.
"If you drop a piece of food on the floor, there's a good chance of picking [bacteria] up instantaneously" depending on the food, said Diez.
Wet foods are more likely to pick up bacteria than dry foods. Flat foods absorb more bacteria than round foods. And dirty floors transmit more bacteria than clean floors. All of those different variables render the five-second rule virtually moot.
"The five-second rule is so general… it is meaningless," said Diez.
If you do drop a large amount of food on the floor, Diez suggested trying to put it back in the oven, as the heat will kill the bacteria.
"Washing it isn't going to do much," he said.
Just because food picks up bacteria doesn't mean that its harmful bacteria, said Diez. "Our body is typically fighting every day against infection," he said, and usually our body wins.
But because there's no way to know for sure what kinds of bacteria are on that hunk of turkey you just dropped, the best advice: "When in doubt, throw it out," said Diez.
(© MMIX, CBS Broadcasting Inc. All Rights Reserved.)
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