Monique Keiran: Don’t risk health with five-second rule

Nature Boy faced a dilemma recently. As the person tasked with the weekly grocery run, he had splurged on tenderloin steaks.

As anyone who has emptied their wallets at the supermarket this summer knows, buying high-end grilling meats almost requires pre-approval from a bank manager. According to Statistics Canada, retail prices for grilling steaks and ground beef increased by about 11 and 12 per cent respectively since this time last year. That’s six times Canada’s overall inflation rate for the same period.

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“Couldn’t we use that money for a vacation instead?” I asked. But Nature Boy pointed out that grilling season was upon us and, besides, the temperature outside simply required use of the barbecue.

“Hmmm, OK. Just this once.”

The dilemma came in the evening. Nature Boy had seasoned and grilled the steaks — rare to medium rare … perfect. He deftly removed them from the heat and placed them on a clean plate. After turning the barbecue off, he took the plate and turned toward the door.

And tripped.

Through an impressive combination of flailing, twisting and flexibility, he saved himself and the plate.

The steaks, however, went flying.

The year’s big vacation landed on the patio paving stones. The juice ran down the sliding doors.

The meat barely had time to settle on the ground, when Nature Boy scooped them back up onto the plate. Phew! He had beaten the five-second rule.

Then, the quandary. Should he brush off the steaks and proceed with dinner as if nothing had happened? Or should he toss them out?

The five-second rule states that food that hits the floor and is rescued within five seconds remains safe to eat. Many people practise it, believing that glancing contact with a surface limits the number of germs food picks up.

An informal study out of the U.K.’s University of Aston suggests a small amount of truth exists in the old wive’s tale.

In the study, biology students monitored the transfer of common, illness-causing bacteria E. coli and Staphylococcus aureus from a variety of floor surfaces onto food over periods of time lasting from three to 30 seconds. They tested toast, cooked pasta, cookies and sticky sweets on carpet, laminate and tile.

The students found that more time on the floor does indeed lead to more bacteria transferring from surface to food. Of course, a food’s wetness or stickiness is crucial — more bacteria transferred to wet or sticky foods. And type of flooring makes a difference, as well, with fewer bacteria transferring from carpeted surfaces and more bacteria transferring from laminate or tiled surfaces to moist foods making contact for more than five seconds.

Carpet’s relative safety may lie in how dropped food — particularly dropped dry food — rests on the carpet’s fibres. This limits the amount of contact area between the food and the surface, and the surface’s bacteria.

However, the study’s leader acknowledges that the primary risk factor for germ transfer in the five-second rule is a surface’s dirtiness. A just-sterilized countertop will present fewer bacteria to cling to dropped food. Outdoor-patio paving stones, on the other hand, are home to vastly greater quantities of bacteria.

Any contact, no matter how brief, between food and a contaminated surface — whether a paving stone, a sidewalk, a dirty kitchen floor or a sink that recently contained raw chicken or pork — will lead to bacteria on the food.

Numerous other studies have shown that enough salmonella and E. coli bacteria will transfer in even one second to sicken a person who eats food that touched a contaminated surface.

So, what did Nature Boy do? He rinsed the steaks off, then put them back on the grill for a few minutes of high-heat sterilization. Cooking at high temperatures destroys E. coli, S. aureus, salmonella and many other bacteria.

The steaks were no longer cooked to perfection. However, we escaped food-poisoning-by-paving-stone, and look forward to next year’s vacation in perfect health.

keiran_monique@rocketmail.com

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