Maturation and storage
Once you have bottled or kegged your beer, treat it well and you'll be rewarded with a beer that remains at or near its peak for many months.
After the beer is bottled it needs to be put somewhere for a week or so to allow secondary fermentation, which carbonates the beer. During secondary fermentation the yeast will consume the priming sugar and turn it into a small amount of alchol and carbon dioxide. Because the CO2 cannot escape from the sealed bottle it dissolves into the beer, carbonating it.
Ideally, secondary fermentation will be at the same teperature as primary fermentation, but in the 18C to 20C range works OK. If it's too cool for the yeast secondary fermentation won't occur and your beer will be flat when you drink it.
While brewers who keg their beers usually force carbonate it is possible, not to mention traditional, to prime the keg and allow natural carbonation to occur. Either way, once the beer is carbonated it's ready to drink.
Beer that has only recently finished fermentation is said to be "green". It will not be well-rounded, possibly have some harsh tastes and probably not taste all that great. However, after a few weeks in the bottle or after being force-carbonated in a keg it will taste much better. Some of the undesirable flavours will have dissipated and hopefully it will be very drinkable. There's nothing wrong with tasting beer in the first few weeks after bottling, and for new brewers it's a good way to learn how flavours develop and improve with maturation.
Most beers are best drunk when fresh. Over time, hop aroma and flavour will be lost, and the malt flavour diminishes. That's not to say you need to drink all your beer within weeks of bottling or kegging, but if left for months on end the beer will not be at its prime, particularly if not stored properly. Drinking old beer won't make you sick; it just won't taste as good as intended and as good as it would have when fresh.
The exception to the "drink when fresh" rule is for beers such as strong ales and imperial stouts that are very malty, highly hopped and high in alcohol, which are at their peak after several years and will keep changing over the years. For example, Thomas Hardy's Ale (12.5 per cent ABV), formerly brewed by Shepherd Neame in the UK, was reported to have still been fantastic after 20 years.
Heat and light are the enemies of beer once it's bottled. And while kegs or a cupboard will protect beer from light, heat can still do plenty of damage.
Heat encourages chemical reactions to occur at a greater rate, meaning beer will lose its hop aroma and flavour, among other things, at higher temperatures than at lower temperatures. In basic terms, heat speeds up the ageing process.
Likewise, light is very bad for beer. When hop bittering compounds in beer are exposed to sunlight a nasty compound called 3-methyl-2-butene-1-thiol begins to form. The taste of this lightstruck beer is described as skunky. This reaction begins the instant light hits the beer and the reason brown bottles, which help protect the beer from light, are preferable to clear or green bottles.
Store bottles upright — it's not wine! But, like wine, storing beer in a cool, dark place will ensure that it remains at its peak for as long as possible. If you have a dry cellar, this is the ideal place to store your beer. Unfortunately most of us don't have a cellar, so find a cool, dry and dark place somewhere in your house. A cupboard in an unheated spare room or under the stairs are places that may be coolest in your house. Conversely, sheds aren't ideal places to store beer if you live in a warm climate because they're likely to get very hot in summer months, particularly if the sun beats down on them.