We have completed maintenance on DiscoverMagazine.com and action may be required on your account. Learn More

Here's how much bacteria you spew on the cake while blowing out birthday candles.

Seriously, Science?
By Seriously Science
Aug 2, 2017 11:23 PMNov 19, 2019 8:55 PM


Sign up for our email newsletter for the latest science news

Photo: flickr/SuzetteIn today's germ-phobic world, many people probably don't want to hear about how much bacteria is in and on their food. But too bad, say these researchers! They did a study of how much salivary bacteria is transferred to the cake when someone blows out birthday candles. And they found that yes, "blowing out the candles over the icing surface resulted in 1400% more bacteria compared to icing not blown on." But hey, nothing says "Happy Birthday" like frosting-covered bacteria... mmm!Bacterial Transfer Associated with Blowing Out Candles on a Birthday Cake "This study examined the potential spread of bacteria when blowing out candles on a birthday cake. Preliminary tests of blowing on nutrient agar indicated that bioaerosols in human breath expelled from the mouth may be a source of bacteria transferred to cake surfaces. To test aerosol transfer to cake, icing was spread evenly over foil then birthday candles were placed through the foil into a Styrofoam™ base. After consuming pizza, test subjects were asked to extinguish the candles by blowing. Icing samples were sterilely recovered then surface plated, to determine the level of bacterial contamination.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." Related content: During every 10-second French kiss, 80 million bacteria are transferred.Washing your hands in cold water works just as well as hot!Microbiologists discover caffeine-adapted bacteria living in the sludge in their office coffee machine.

1 free article left
Want More? Get unlimited access for as low as $1.99/month

Already a subscriber?

Register or Log In

1 free articleSubscribe
Discover Magazine Logo
Want more?

Keep reading for as low as $1.99!


Already a subscriber?

Register or Log In

More From Discover
Recommendations From Our Store
Shop Now
Stay Curious
Our List

Sign up for our weekly science updates.

To The Magazine

Save up to 40% off the cover price when you subscribe to Discover magazine.

Copyright © 2024 Kalmbach Media Co.