After a bit of a summer hiatus, I am back to blogging about my favourite pass-time: brewing beer.
A question that is often asked: how long does beer last before it spoils or takes on off-flavours? As you might have guessed, it really depends on a number of factors.
Factors Affecting the Shelf Life of Beer
The first question is how are you storing your beer? Is it still in a fermenter? Beer is more stable in a bottle or a keg because both have better insulation from the harmful effects of light; there is less head space and it’s not coming into contact with the trub. Leaving beer sitting on trub for any time that is longer than necessary is never a good idea. Yeast cells decay over time and as the cell membrane breaks, it releases compounds that produce off-flavours.
Clear beer is more stable than cloudy beer and it will keep longer. The chill-haze that you find in unfiltered or unrefined beer is actually cold-break material made of protein that will give you beer a stale taste over time.
Warm temperatures are another factor that can drastically affect the stability of beer. Beer stored at cellar temperatures are ideal. Very warm temperatures will have a detrimental affect on beer. Too cold is not good either because the prolonged exposure to cold temperatures tends to make some flavour producing compounds to clump together and fall out leaving a beer, leaving a more bland and less tasty than when first produced. This is not so important with Pilsners as they are meant to be light tasting, but it can be an issue with IPAs and other styles that rely on those flavour producing compounds to be there.
Sunlight and even fluorescent light is a beer killer and it will make your beer smell skunky fast. I had put some beer I was brewing in my kitchen once because I needed higher fermentation temperatures, and I was shocked by how fast the fluorescent lights brought on a skunky smell to my brew fermenting in a carboy. It doesn’t take long. If exposed to the sun, it can happen in an hour.
The gravity of your beer is also an important factor when considering how long your beer will last. As you already know, alcohol is a very effective disinfectant. So, the higher the alcohol content of your brew, the longer it’s shelf life. The hop content of the beer also plays a role. I think that IPAs are better young because that is when the hop characteristics will come out, but the beer will still be very tasty a year or more.
Regardless of how long beer lasts, as an organic product, it always changes over time. Many beer styles mellow out over time and are actually better once a few months have past, and this is especially true for those higher gravity concoctions, like barleywine and strong Scottish export styles. As usual, good sanitation, a good storing cellar, clear and properly packaged beer will last a year or more. Just be sure to consider some of the factors above and you can be drinking that Christmas homebrew in August.