The question: Does beer have an expiry date?
The answer: You bet, though a good Canadian should not be letting beer sit around long enough to warrant the question. A good rule of thumb is about four or five months.
Longevity depends on the style of beer and how it has been stored, but most will have certainly kicked the bucket before they're a year old. Like bread, that other glorious product of fermented grain, beer is perishable. Unlike bread, it contains alcohol and hops, both of which help in preservation. If you want to prolong its life, store it in a cool place, out of sunlight.
Many breweries supply either a bottling date or best-before date. These will be stamped either on the carton or bottle. Unfortunately, there's no standard format, and the codes can be harder to crack than the Pentagon's missile-command network. Some may employ letters denoting the month of production, as in A for January, B for February, and so on, with numbers representing the day and year. For example, B1412 would be February 14, 2012. But those codes are often strung together with lot-production numbers and the like, so it's a bit like finding Waldo. And you have to keep in mind that alphabetical-order codes often skip the "I" because the letter can be confused for the number 1. In fairness, some breweries do make things easy, carrying actual best-before dates in standard mm/dd/yyyy format. Just don't neglect to check the bottom of the carton; they're sometimes hiding there.
Although most beers are at their best when they leave the brewery, some styles can improve with age. Notably, this includes so-called bottle-conditioned beers, which contain active yeast that helps with preservation and continues to evolve the flavour, and some malty, sweet or dark beers weighing in at more than 8 per cent alcohol. The flavours can become softer over time, with less of the bitter hop aroma, while oxidation over time can yield nutty complexity.
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