Why Does Beer Explode in the Freezer (And Is It Still Good?)

Have you ever brought home a case of room-temperature beer and thrown one in the freezer to cool it down fast? If so, you may have also walked away for a while and came back to a sticky mess. What is it that causes beer to explode in the freezer?

Beer is 90-95% water and it will expand when frozen, bursting open the bottle or can. Freezing beer can cause issues with carbonation and flavor, and the risk of broken glass or metal fragments means it is unsafe to drink a beer that exploded in the freezer. It is safe to drink if the beer is still slushy and hasn’t broken the container’s seal.

Read on to find out more about frozen beer, its drinkability, and some bonus tips on making beer slushies (on purpose).

What makes beer explode in the freezer?

If you’ve ever brewed beer, you’re familiar with the large amounts of water that go into each recipe. Most homebrewers know the feeling of standing impatiently over the kitchen sink, waiting for a 5-gallon brew kettle to fill. All of that water makes up upwards of 90% of the finished beer. But what is it about water that makes it freeze and expand in the first place?

The molecules in water float around sort of randomly, forming and breaking loose hydrogen bonds. As water’s temperature lowers, those molecules slowly stop moving, eventually forming strong bonds that remain firmly in place. These bonds form in a more spread out yet orderly hexagonal formation, allowing as many bonds as possible to form in the given water sample.

Because of this, water expands 9-10% when it is frozen. This is also why ice cubes float: because ice is less dense than liquid water.

The alcohol in beer freezes at a much lower temperature. Pure ethanol (alcohol) freezes at -173°F. Because home freezers or even porches in the winter won’t reach anywhere near that temperature, the alcohol in the beer will almost always remain a liquid even once the water has frozen. 

It’s the pressure of the expanding, frozen water which causes cans and bottles to burst, allowing the still-liquid alcohol and slushy watery areas around it to seep out, sometimes all over the bottom of your freezer.

How long does it take for beer to explode in the freezer?

Many factors contribute to the time it takes a beer to go from optimal drinking temperature to frozen mess.

The alcohol content, size of the container, and temperature of the environment are all contributing factors. Higher-alcohol beers will take longer to freeze than others. A 40oz bottle will, of course, take longer to freeze than a 12oz can.

In general, a standard 12oz beer will freeze in a freezer set at 0°F in about 90 minutes. To be safe, it’s good to set a timer for 30 minutes after placing a room temperature beer in the freezer to chill and check it regularly from that point on. 

How do you stop a frozen beer can from exploding

You can’t fight science, so there’s no foolproof way to stop a can or bottle from rupturing in the freezer besides taking it out before it gets to that point.

A better, more worry-free way to quickly chill a beer is to place it in a bucket, pot, or cooler of salted ice water. The salt lowers the freezing point of the water, allowing it to get even colder than 32°F.

This will allow your beer to cool down even faster than it would in the freezer, without fear of a pesky beersplosion.

Is beer still good if it freezes?

If frozen beer has ruptured the can or bottle it’s in, it’s almost definitely not salvageable. The rupturing of the vessel will cause the CO2 to escape, rendering your beer totally flat. Furthermore, a ruptured bottle means dangerous shards of broken glass. Never drink beer from a broken bottle, even if it seems like it’s broken in one piece. 

If your beer is still sort of slushy and has not ruptured the seal of the container it’s in, you may still find it drinkable. In cans, for example, the top ‘lid’ portion may swell up and protrude above the top of the can before actually breaking the seal.

Ultimately, like so many things about beer, the best way to test it is to taste it.

Follow these steps to determine if a frozen beer is salvageable:

  1. Remove it from the frozen environment immediately. Whether it’s your freezer door, the trunk of your car, or a snowy porch, get any frozen or partially-frozen beer out of frozen temperatures immediately.
  2. Place it in a refrigerator to thaw before opening or drinking. If you open the beer right away, you may be lulled into a false sense of security by liquid that may seem like it ‘hasn’t frozen yet.’ This is, of course, pretty much pure alcohol! Not only will it knock you out, it won’t necessarily be super tasty to drink. Patience is the key here! Let that puppy thaw.
  3. Carefully crack it open and give it a try. Once thawed back to its liquid form, taste it! Freezing beer can have majorly negative effects on quality and taste. Depending on how frozen it was, though, it may still taste pretty close to how it should. 

Does frozen beer lose alcohol?

Frozen beer doesn’t lose alcohol.

The different freezing points of water and alcohol will naturally cause the alcohol to separate from the rest of the beer.

It is not recommended to drink this alcohol, but rather to thaw the beer and let it reincorporate before consuming. 

Does freezing a beer make it stronger?

Some people think freezing beer is a way to make it stronger. However, freezing beer doesn’t add any alcohol to the beer itself.

Because freezing separates the alcohol, it is, theoretically, a way to extract concentrated ethanol. Though this may sound like a fun way to get drunk as quickly as possible, the taste and general experience of drinking this liquid are not fun and not recommended.

If you’re looking for a high-ABV party, switch to spirits or a high-gravity beer!

Can you make frozen beer slushies?

If you want to make a frozen beer slushie, it’s as long as you follow the right steps – that is, don’t just throw your beer in the freezer; you follow the right steps.

While making any beer slushie, here are a few guidelines to follow for the most success:

  • Freeze beer in a shallow, freezer safe container with room to expand – By now you understand how much water expands once frozen, so you’ll want to allow room for that. Freezing in a shallow container also means more surface area for crystals to form, rather than large blocks of solid ice.
  • Incorporate other liquids or flavorings – A little bit of juice and/or simple syrup will go a long way to balance out the bitterness and booziness of frozen beer. Juice also adds some nice acidity to balance things out.
  • Blend it – Though some beer slushie recipes may instruct you to scrape frozen beer right out of a tray and into a glass, blending it for just a little bit ensures a smooth texture that’s super fun to drink!

If you’re planning on trying out a frozen beer slushie, I recommend this Chili Mango Beer Slushie recipe from Kip Barnes of Los Angeles Ale Works.