Frozen glasses and the harm they do to a good beer
In Indian heat, a mug straight from the freezer seems like the obvious answer. It numbs the beer's flavour, foams it, waters it down and can make it smell of the freezer. A cool glass works better.
Why frosted mugs are popular
On a 38 °C afternoon a frosted mug feels like relief. Many bars and restaurants keep a chest freezer of glasses for exactly this reason. Some customers ask for one. We understand the appeal. Nobody wants a warm beer.
The problem is that a frozen glass does several things to the beer at once. Nearly all of them are bad. The beer foams more, loses carbonation faster, tastes of less and can pick up smells it should not have. There are better ways to keep beer cold.
Ice crystals make the beer foam
A glass at minus 15 to minus 18 °C, the temperature of a typical freezer, gathers a layer of ice crystals the moment it meets warm air. Those crystals are rough. Rough surfaces give dissolved carbon dioxide somewhere to form bubbles, a process called nucleation.
Pour beer onto that surface and the gas leaves in a rush. You get a tall, loose head that collapses into a flatter beer. The bartender often has to pour slowly and top up, wasting beer. The carbonation that should carry aroma and add a light bite to each sip has gone into the foam instead of staying in the glass.
Too cold to taste
Most lagers are at their best around 3 to 7 °C. Pour a 4 °C lager into a frozen glass and the beer near the wall can drop below zero. Some can even freeze into slush, since a 5% beer begins to freeze only a degree or two below 0 °C.
At those temperatures your tongue is numbed and almost no aroma rises from the glass. A cheap lager may survive this, because there is little to lose. A craft lager, a wheat beer or a pale ale loses most of what the brewer worked for. Our guide to beer serving temperature gives the range for each style.
Melting ice waters the beer down
The frost on a frozen glass is water. As the beer goes in, that frost melts into it. With a heavy layer of frost, especially from a freezer that is opened often in a humid room, the dilution is enough to taste: thinner body and less flavour.
Glasses washed and put into the freezer wet are worse. The water film freezes into a solid layer that melts straight into the beer. This also makes the glass more likely to crack, since thick glass taken from minus 18 °C into warm liquid is under stress.
Freezer smells end up in your beer
Freezers hold more than glasses. Fish, onions, meat and ice cream all share the same air. Frost on a glass picks up those odours. When it melts into the beer, you can taste a faint fishy, oniony or stale freezer note. Foam carries aroma to your nose, so even a small amount is noticeable.
A dedicated glass freezer helps, but it does not fix the foaming or dilution. A fridge set to 2 to 4 °C, or a quick cold water rinse, gives you a cool glass without any of these problems.
Better ways to beat the heat
The real goal is a beer that stays cold and fresh from the first sip to the last. A frozen glass is a poor tool for that because it chills the beer in the wrong way. These work better:
- Keep the beer itself at the right temperature, around 3 to 5 °C for most lagers, in a fridge that is not opened every minute.
- Pour smaller measures. A 300 ml glass finished in ten minutes stays colder than a 500 ml mug left on the table.
- Choose a thicker glass or a stemmed one, so your hand warms the beer less.
- Sit in the shade. A glass in direct afternoon sun warms several degrees in a few minutes.
None of these fight the beer's flavour. They simply keep the beer in the range where it tastes the way it should, which a frozen mug cannot do.
What a good cold glass looks like
- Clean and beer clean, with no grease or detergent film.
- Cool, not frozen: from a fridge at 2 to 4 °C, or rinsed under cold water just before the pour.
- Wet on the inside, so the beer slides down and forms a steady head of about two fingers.
- Held by the base or the stem so your hand does not warm it.
Keep the beer cold instead of the glass. A beer stored at the right temperature in a properly set fridge does far more for freshness than any frosted mug.
Next time, ask for a normal glass
Next time a bar offers a frosted mug, ask for a regular glass and compare it with a friend who takes the frozen one. Smell both, then taste. If you have a glass freezer at home, move the glasses to the fridge for a week and see whether you miss the frost.
Common questions
Is a frozen glass good for beer?
Not really. Ice crystals make the beer foam and lose carbonation. The frost dilutes the beer and the cold numbs its flavour.
What temperature should a beer glass be?
Cool rather than frozen. A glass from the fridge at 2 to 4 °C, or rinsed in cold water just before pouring, works well.
Can beer freeze in a frozen glass?
Yes, beer near the wall of a very cold glass can turn to slush because most beers freeze only a degree or two below 0 °C.
Why does beer from a frosted mug taste strange?
Frost can carry odours from other food in the freezer. It melts into the beer as you drink.
