As an expert sommelier and brewer, I can provide you with a detailed answer to the question of whether you can leave a keg tapped.
When it comes to kegs, it is generally recommended to consume the beer within a certain timeframe after tapping. The reason for this is that once a keg is tapped, it is exposed to oxygen. Unlike carbon dioxide, which is used in traditional kegs to dispense beer, oxygen can cause the beer to go flat and spoil quickly.
The exact length of time that a tapped keg will last depends on various factors, including the type of beer and how much oxygen was pumped into it during the tapping process. Generally, a tapped keg will last anywhere from 12 to 24 hours before the beer starts to lose its carbonation and freshness.
It's important to note that not all beers are created equal in terms of their shelf life once tapped. Certain beer styles, such as hop-forward IPAs, tend to degrade more quickly when exposed to oxygen compared to more robust and malt-forward styles like stouts or porters. Additionally, higher alcohol content beers tend to have a longer shelf life once tapped.
Personal experiences have taught me the importance of finishing a keg within the recommended timeframe. On one occasion, I left a tapped keg untouched for about 48 hours, thinking that it would still be drinkable. However, when I finally poured a glass, I was disappointed to find that the beer had lost its carbonation and had a stale, oxidized taste. It was a valuable lesson in the importance of consuming beer promptly after tapping.
If you find yourself unable to finish a tapped keg within the recommended timeframe, there are a few steps you can take to try and extend its shelf life. Firstly, keeping the keg refrigerated at a consistent temperature can help slow down the oxidation process and preserve the beer for a little longer. Additionally, using a kegging system that replaces the oxygen with carbon dioxide can also help mitigate the effects of oxidation.
While it is technically possible to leave a keg tapped, it is not recommended due to the potential for the beer to go flat and spoil quickly. To ensure the best quality and freshness, it is advisable to consume the beer within 12-24 hours of tapping. However, if necessary, taking steps such as refrigeration and using a carbon dioxide-based kegging system can help prolong the shelf life of a tapped keg.