As a sommelier and brewer, I can assure you that it is generally safe to drink flat beer. However, it is important to note that the flavor of a beer will degrade over time, especially when exposed to light, oxygen, and heat. These factors can cause the organic compounds in beer to break down, resulting in a less desirable taste and aroma.
When beer goes flat, it means that it has lost its carbonation. This can happen naturally over time or due to improper storage conditions. Carbonation is what gives beer its characteristic fizz and can contribute to its overall mouthfeel. So, while flat beer may not be as enjoyable to drink as a properly carbonated one, it is still safe for consumption.
It is worth mentioning that some beer styles, such as certain traditional Belgian ales or English cask ales, are intentionally served with lower carbonation levels or even completely flat. These styles are appreciated for their unique flavors and aromas, which are not dependent on carbonation. So, in the case of these specific beer styles, drinking flat beer is not only acceptable but can even enhance the drinking experience.
When it comes to the degradation of flavor in beer, it is important to understand that it is a gradual process. The rate at which a beer's flavor deteriorates will depend on various factors, including the beer style, storage conditions, and the presence of light, oxygen, and heat. Generally, lighter and more delicate beer styles, such as pilsners or wheat beers, will show signs of flavor degradation sooner than stronger and more robust styles like stouts or barleywines.
To slow down the degradation process, it is crucial to store beer properly. This means keeping it away from direct light, as UV rays can cause skunking, a phenomenon that imparts an unpleasant aroma and taste to the beer. Oxygen exposure should also be minimized by sealing the beer tightly and storing it in a cool place. Heat can accelerate the breakdown of organic compounds, so storing beer in a cool environment is essential to preserve its flavor.
While the flavor of a flat beer may not be as vibrant or fresh as when it was first carbonated, it is still safe to drink as long as it has been stored properly and is not past its expiration date. However, if you notice any off flavors or unpleasant aromas, it is best to exercise caution and consider discarding the beer.
Drinking flat beer is generally safe, although the flavor may have degraded over time. Proper storage and handling can help slow down the degradation process, but eventually, all beers will lose some of their desirable qualities. So, while it may not provide the same sensory experience as a freshly carbonated beer, there is no harm in enjoying a flat beer, especially if it is a style that is traditionally served without carbonation.