Blowing out cake candles boosts frosting bacteria by 1,400 percent

Calling all party poopers, this one's for you! But for the most part, it’s not the end of the world for birthday cake eaters.

I’m not a germaphobe at heart, but sometimes things that one can't unsee give a little nudge in that direction. Like the time I witnessed a sneezing-hacking-oozing boy wipe his wetted-with-body-fluids hand on the subway pole, and ever since I have devised all kinds of interesting ways to avoid ever touching a subway pole with my bare hands again.

Now that I’ve read a study titled “Bacterial Transfer Associated with Blowing Out Candles on a Birthday Cake,” will I become a frosting scraper-offer? And what kind of Scrooge would come up with such a study? A Grinch, for sure, someone who does rain dances before parades, no doubt.

Writing in The Atlantic, Sarah Zhang wondered the same thing. “So I called up Paul Dawson, a professor of food safety at Clemson University and one of the authors of this study,” Zhang writes, “to ask why someone would want to ruin birthday parties.”

The study in question looked at the potential spread of bacteria when blowing out candles on a birthday cake. The conclusion:

Blowing out the candles over the icing surface resulted in 1400% more bacteria compared to icing not blown on. Due to the transfer of oral bacteria to icing by blowing out birthday candles, the transfer of bacteria and other microorganisms from the respiratory tract of a person blowing out candles to food consumed by others is likely.

As Zhang explains, Dawson said the idea for the study came from his teenage daughter. “But he’s also conducted a whole set of studies around common questions in food safety with his undergraduate students, as a way of engaging them in original scientific research," she writes. Things like the five-second rule and double-dipping.

Dawson told Zhang that the bacteria itself wasn’t that surprising, but how much it varied from blow to blow was. “Some people blow on the cake and they don’t transfer any bacteria. Whereas you have one or two people who really for whatever reason ... transfer a lot of bacteria.”

But even so, it’s probably not much cause for alarm. “It’s not a big health concern in my perspective,” Dawson says. “In reality if you did this 100,000 times, then the chance of getting sick would probably be very minimal.” Adding that he would likely avoid the cake if the celebrant were obviously sick.

So now that the image is cemented in your brain, you can go easy knowing that a mist of saliva on your slice of cake probably isn’t going to hurt you. But if the birthday girl has the flu, you may want to avoid that frosting...

The reserach was published in the Journal of Food Research.

Tags: Diseases | Food Safety | Health

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