How Long Does Beer Last Once Opened?

Whether you can drink an open beer depends on a few factors, including how long it's been open, how it's been stored, and what it tastes like. If a beer has been left open and unrefrigerated for a few hours or overnight, it's probably still safe to drink, but it might not taste very nice. Beer can go flat quite quickly once opened, losing its carbonation, bitterness, and sharpness. It's recommended that beer is consumed within 24 to 48 hours of being opened to avoid this, and to minimise the risk of spoilage.

An open beer is safe to drink for a few days but will taste bad

An open beer is generally safe to drink for a few days but it will taste bad.

Once a beer is exposed to oxygen, its flavour starts to deteriorate in a process called oxidation. This process happens faster when the beer is left in a warm place, so it's best to store it in the fridge. Even then, an open beer will only taste fresh for 1-2 days. After that, it will start to go flat and lose its flavour, aroma and complexity.

While it may be safe to drink an open beer left out overnight, it will likely be flat and have lost its flavour. Beer is best stored in a cool, dark place, like a pantry or cellar, and drunk within 24-48 hours of opening to enjoy its optimal taste and quality.

If you don't finish a beer, you can try to preserve its freshness by keeping it in the fridge and sealing the bottle or can tightly. This will slow down the oxidation process and help maintain its freshness for a little longer. However, even in cold temperatures, the beer will continue to be exposed to oxygen and its overall quality and taste may still be affected.

An open beer that has gone bad will likely be cloudy and darker in colour. It might also have particles or sediment floating in it. Off-smells, like vinegar or rotten eggs, and unusual flavours, like sourness or excessive bitterness, are also common in spoiled beer. If you notice any of these signs, it's best to avoid consuming the beer as they indicate spoilage or contamination.

Oxygen and UV light cause beer to lose flavour and go stale

Oxygen and UV light are two of the biggest culprits when it comes to causing beer to lose flavour and go stale.

Oxygen

Oxygen is a contaminant that can spoil the long-term stability of your beer's flavour and clarity. It can lead to a variety of off-flavours and a stale taste, even in small quantities. Oxygen interacts with polyphenols and tannins in the beer to create chill haze and eventually a permanent haze in the beer.

UV Light

UV light, particularly in the 350-550 nanometer range, can cause beer to "skunk". This is due to the interaction of UV light with isomerised hop compounds, creating 3-methylbut-2-ene-1-thiol (3-MBT). The presence of 3-MBT results in a distinct skunk character, also known as "lightstruck" beer. While sunlight is the biggest offender, LED and fluorescent lights can also contribute to skunking.

To prevent oxygen and UV light exposure, brewers should take precautions such as using opaque or amber-coloured bottles or fermenting and storing beer in stainless steel containers, which block out light and oxygen. Additionally, minimising beer transfers and avoiding splashing during bottling can help reduce oxygen intake.

Beer should be stored in a cool, dark place

Beer is best stored in a cool, dark place. This is because exposure to sunlight and heat can cause the beer to spoil. The sun's UV rays can cause a chemical reaction in the beer, breaking down its flavour components, until it smells and tastes like skunk spray. This is known as the beer being "skunked" or "lightstruck".

The ideal temperature for storing beer is between 45 and 55 degrees Fahrenheit, or 10-13°C. Beer can be stored in a refrigerator to extend its life by up to two years. Beer should also be stored upright to limit air contact.

If you are storing beer in a bottle, opt for darker bottles that block out UV rays. Green bottles are also recommended. Amber bottles offer better protection from light than clear bottles.

If you are storing beer in a keg, keep it in a cool, dry space, away from other foodstuffs. Avoid moving kegs around too much, as this can increase the amount of foam that spurts out when you tap the keg.

If you are storing beer in a growler, keep it upright in a cool, dark space. The airtight lid will keep the beer fresh for several days. Once opened, the beer will stay fresh for up to 36 hours.

If you are storing beer in a can or bottle, keep it just below room temperature or just above typical refrigerator temperatures. If you don't have a way of measuring the temperature, you can keep your unopened beer in the fridge, where it will remain at its best quality for up to eight months. You can also keep unopened cans or bottles at room temperature, where they will stay at their best quality for up to six months.

An open beer can be salvaged by using an airtight container

To prevent this, an airtight container is the best method. Oxygen is the main culprit when it comes to spoiling beer, as it causes the beer to oxidise and lose its malt and hop flavour, resulting in an unpleasant taste and smell. By using an airtight container, you can prevent oxygen from reaching the beer and slow down the oxidation process.

It is also important to keep the beer chilled. Lower temperatures slow down the oxidation process, extending the shelf life of the beer. Ideally, the beer should be chilled from the start and stored in a cool, dark place.

Beverage canisters, recycled plastic soda bottles, and vacuum-sealed bottles with rubber stoppers are all effective airtight containers for storing open beer. Additionally, a few drops of sterile beer salts can be added to the beer to create an environment where germs cannot thrive. This is especially beneficial for stronger alcoholic brews, which are more prone to oxidation.

It is important to note that even with proper storage, open beer will only last for about a week before it starts to lose flavour and quality. Therefore, it should be consumed promptly and monitored for any signs of spoilage, such as an unpleasant flavour, a musty smell, or visible mould.

Flat beer can be used for cooking, cleaning, or self-care

Cooking with Flat Beer

Beer can be used in cooking, adding flavour and texture to various dishes. It can be used to deglaze pans, added to braises, sauces, stocks, marinades, and more. For example, a traditional Belgian stew called Waterzooi uses local beer, and Carbonnade Flamande is the Belgian version of Boeuf Bourguignon that substitutes hearty Belgian beer for burgundy wine. When cooking with beer, it's important to understand the taste profile, as different beers will bring out different nuances in the dish. Wheat beers and lambics pair well with chicken and seafood, while stouts complement chocolate and other sweets with their nutty, molasses-like notes. The carbonation in beer also lightens the texture of batters, making them crisp and delicate.

Cleaning with Flat Beer

Flat beer has unexpected cleaning abilities. It can be used as a stain remover on carpets and other surfaces. Simply pour flat beer over tough coffee or tea stains, rub it in, and blot the area with a clean, dry cloth. Beer can also restore dull wood furniture by pouring it onto a cloth and rubbing it onto the surface before wiping it down with a dry cloth. Additionally, the carbonation in beer helps loosen rust from metal surfaces, bolts, and hardware.

Self-Care with Flat Beer

Flat beer can even be used for self-care routines. The vitamin B and sugars in beer can add shine and volume to hair. Applying beer to washed hair, waiting a few minutes, and then rinsing thoroughly with cold water can lead to gorgeous, voluminous locks.

Frequently asked questions