When Beer Goes Flat Does It Lose Its Alcohol?

Few things in this world are worse than accidentally drinking a flat beer. Imagine spotting a refreshing cold beer that was left out on the patio for a few hours. You pick it up and take a giant gulp, only to find out that the beer is not only warm but also flat. A warm beer is unpleasant to drink, but what about the alcohol content? When beer goes flat, does it lose its alcohol?

Ultimately, beer does lose some of its alcohol content within the first 12 hours of going flat IF it is continuously exposed to air. But the alcohol in the beer can be preserved if the bottle or can is sealed and protected from the air. Ethanol Alcohol does not break down; it will evaporate into the air. The carbonation cannot be preserved for long after opening. It is not a good idea to drink an open can of beer that has been sitting out for days. But you can still get drunk from a beer that has been open for a month if it is resealed.

If you would like to know why does beer go flat, wow fast does alcohol break down, can you still drink a beer if it has been sitting out in the sun, and two reasons why you shouldn’t drink a flat beer, then continue reading to find out!


What Happens When a Can or Bottle of Beer Goes Flat?

Accidentally drinking a bottle of flat beer or soda is so disappointing. And the worst part is that once a can or bottle of beer is opened, it cannot be resealed again. All of the carbon dioxide that gave the beer its fizziness has escaped.

There is no way to add the carbonation back into the drink. But if beer or soda can sit for months in the back of a warehouse without compromising its carbonation, then why does a can or bottle of beer go flat in a few hours?

Beer goes flat in a few hours after it is opened because of the loss of carbon dioxide. When a beer is brewed, the brewing process includes a step called fermentation. During the fermentation step, the yeast inside the beer is converted to carbon dioxide and ethanol alcohol. So, the fermentation process is what gives beer its alcohol content and its own natural carbonation.

Once the fermentation process is over, the beer must then be bottled and canned. After the containers of beer are filled, a machine will seal the opening of the beer can or bottle with an airtight seal. The airtight seal prevents the carbon dioxide from escaping.

On average, the carbon dioxide inside of a beer or a soda can last about six months before it begins to break down and lose its fizz. But when a can or bottle of beer is opened, most carbon dioxide will escape into the air. The rest of the carbonation will leak out of the beer in a few hours.

Other Types of Fermented Drinks

Another type of fermented drink that develops carbon dioxide due to the fermentation process is kombucha drinks. Some natural healthy sodas don’t contain much sugar and get their carbon dioxide and fizz from their special fermentation process. But these fermented drinks are usually found in health stores and not at your local Wal-Mart.

Why Does the Alcohol Inside a Beer Break Down?

It’s time to learn some chemistry. In a nutshell, alcohol has a much lower boiling point than water. So, it is much easier for alcohol to evaporate in normal weather and especially on a hot day. Water will not evaporate at such a low point.

Alcohol doesn’t break down. It just evaporates into the air. But even on the hottest summer days, the rate of evaporation is very low. On average, a can of beer will lose 30% of its alcohol by evaporation in around 12 hours.

Be sure to protect your wine, beer, or hard liquor from being exposed to the open air, or else the alcohol will evaporate at a slow but steady pace. If your liquor is left out for an hour or so, there’s no need to worry.

This means if the beer bottle or can is sealed and not left to sit out in the open air, the alcohol content will stay at the same level for a year or more. So, if you open a beer but let’s save it for later, be sure to seal it back up and put it in the fridge. The beer will go stale, but the alcohol will evaporate away.

What if I Cook with Beer?

What if I cook with beer? Does it lose alcohol?

There are plenty of recipes out there that Acquire a glass of wine or a pint of Guinness. But do these recipes contain the same amount of alcohol as the drinks themselves? Well, the answer is: it depends on how long the food is cooked. Alcohol evaporates at 172 degrees Fahrenheit, so the food must first reach this temperature for it to evaporate thoroughly.

If a person adds beer to a hot pan and allows it to reach 172F, it will still have 35% of its original alcohol content after 30 minutes of cooking. In order for the meal to drop to 5% of the original alcohol content, it must be cooked for 2.5 hours. So, the higher the alcohol content, the longer it must cook, so it won’t affect anyone who eats the food.

As a side note, for a cup of wine to lose 70% of its alcohol content, it must be simmered or boiled for at least 45 minutes on a hot stove.

The average beer is only 5% alcohol. If it cooks for 30 minutes, the alcohol content of the food will only be 1.75%.

Is There a Way to Stop a Beer From Going Flat?

Sadly, no. Once a can or bottle of beer is opened, it is only a matter of time before it goes completely flat. But there is a way to preserve the carbonation in a beer and make it last longer. The carbonation in an opened can or bottle will not last weeks, but it can last a day or two. To preserve the carbonation in a beer, it must be quickly sealed after it is opened.

The cover or seal must be completely airtight, so it will not allow carbon dioxide out or any oxygen inside. The airtight seal will keep the carbon dioxide inside of the beer, and the drink’s fizziness will last a day or two. In the event you or someone else opens a beer but doesn’t want to drink it, its flavor and carbonation can be preserved for another day.

Can I Drink Flat Beer?

Yes, you can drink a flat beer that has been opened, and all of its carbonation is gone. Some people whose stomachs cannot handle a lot of carbonation are used to drinking flat beer and soda, so it is perfectly safe. But the taste will be lackluster, especially if the beer is cheap.

If you are drinking a premium or expensive beer, the carbonation may last longer. Premium beers are also known to still have a good flavor, even after all of the carbonation is gone.

If a can of beer is found opened, but no one wants to drink it, place it in the fridge. Someone can drink it in a few hours, or they can drink it tomorrow.

When Should a Person Not Drink Flat Beer?

When Should a Person Not Drink Flat Beer?

If a closed can of beer is opened, and there is no sound of carbon dioxide escaping, then the drink is completely flat. The beer has gone bad during the brewing or shipping process, and no one should drink it.

It could be severely contaminated and have toxic bacteria that could make you extremely sick.

What about Rotted Beer?

Old, rotted beer that has been opened and sitting out for weeks can contain all of its alcohol as long as it was sealed. The rotted beer can turn a drinker tipsy if they consume it. But the drinker will become sick from the rotted yeast.

The alcohol content from an old flat beer is not worth vomiting all night. There is a choice between drinking rotted beer and getting dressed and walking to the liquor store, and the drinker should always choose the liquor store.

Final Thoughts – Does Flat Beer Lose Its Alcohol Content?

Yes, flat beer does lose its alcohol content, albeit at a very slow rate. The alcohol will evaporate into the air since it has a low boiling point. But if an open bottle of beer is resealed, the alcohol will not evaporate into the air; the beer will still be flat, though.

A person who drinks a beer sitting in the fridge for five days will still be affected by the alcohol inside, but their stomach may not like the 5-day old ingredients inside the beer. Cooking beer will not instantly cause the alcohol to evaporate away. A meal with alcohol as an ingredient will have to simmer without a lid for 2.5 hours to finally get down to 5% of its original alcohol content.

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