How do you cool down a hot drink? Do you toss in an ice cube? Blow across the top? Leave a spoon in it? Stir? There are many ideas on what cools a hot beverage down the fastest, but not to worry, we can always count on Science to tell us which one is best!
Over the holidays we found ourselves doing a little light reading and in this case, it was Molecular Gastronomy, Exploring The Science of Flavor. Think of it as the French to English translation of all the fantastic science-y bits of Alton Brown's Good Eats. They obviously had a ball testing theory after theory for their publication and we're here to share a little bit of their findings.
To start, they tested the effects of leaving a teaspoon in a drink vs. adding milk to a hot drink. They tested both methods on a beverage that had been boiled in identical cups, in identical amounts. The teaspoon barely registered an increased rate of temperature loss, while the milk was an improvement — but not as much so as the next two options.
Up next was stirring and blowing. Their stirred beverage lost 6 degrees per minute. Then the same test was performed while blowing across the surface of the liquid. This resulted in a loss of 11 degrees per minute, almost twice the previous test.
Though you might look silly doing it, the combination of blowing while stirring your extra-hot beverage will allow you to drink it fastest! This will maximize the surface area of contact between the air and the liquid giving you a loss of 20 degrees per minute. Winner!
So no more burned lips and tongue. In just one minute of your time you can reduce the temperature of your drink back down to something palatable instead of mouth-scalding!
• Related: Definitely Try This! Tea-Infused Hot Chocolate
(via: Molecular Gastronomy, Exploring The Science of Flavor)
(Image: Flickr member Marco Arment, licensed for use by Creative Commons)

Comments (13)
Probably could have done this at home... but I'm a bit lazy. I like my tea piping hot if possible. My wife on the other hand will be happy to learn this information. She likes soup and tea at room temperature before drinking/eating.
Put it in a very cold container.
i lived in india for a year and we would buy hot tea on the street twice a day. They cool it by pouring from one cup to another with a lot of space in between the cups. the exposure to the air cools it down. plus the process is very dramatic. see example herE: http://www.worldofstock.com/slides/PFO11338.jpg
@manjar, sounds like a good way to crack your teacups to me.
I could be wrong on this, but I always thought that other than the initial cooling of adding cold to hot, milk actually helps keep a drink hot - the fat in the milk helps trap the heat in.. or so I've been told.
luke,
I saw the Indian cup-to-cup technique in a documentary and was fascinated. Sadly, I've never had the nerve to use it anywhere indoors for fear of spillage. But it does work like a charm!
An ice cube?
Wait.
If I need to cool something quickly, I place it in a another container with cold water in it. Water has a high heat capacity & thermal conductivity and absorbs the heat quickly. It doesn't get diluted, as it would if you put an ice cube in it. And if you're reeeeally in a hurry you can also stir blow at the same time!
Slightly related: I love to drink coffee or tea from a wide, shallow bowl cup. The increased surface area actually lets the liquid cool quickly---which means, you can actually drink it while it is still very hot, but not hot enough to burn your mouth. My favorite cups are paper-thin bone china. Pretty and practical. I don't care for mugs at all.
I also used the Indian "pour-from-cup-to-cup"-technique for cooling boiled water down for my green tea - one step is said to lower the temperature by about 5°C, I think.
Definitely cup-to-cup! It's the way to go. Also, in India they pour tea out into the saucer and slurp from the saucer. Not ideal in public, but works great at home!
I live in the South where it can be extremely hot, but I do love me some chamomile tea before bed.
May I suggest a martini shaker with ice?
The key is a lot of ice and some quick shaking. I think this does the best job of cooling without diluting the beverage.