FireGryphon wrote:How do you know which beers will still taste good if you store them, and which will turn bad? I purchased 24 bottles of assorted beer from the Brooklyn Brewery here in Brooklyn, and when I got them home I discovered that there were expiration dates on at least some of them. They tasted great fresh, but the ones that got left around for a few months turned a bit bad. They were all kept in my fridge, which is colder than most, and the bottles were all brown. So what is it that makes beer last or not last, and how can you tell?
Strength is the big thing. More alcoholic/higher original gravity beers age better and take longer to develop. That's why people celler and age brew like barleywines, dubbels, etc. rather than weaker varieties. I'd imagine lagers or macrobrews would probably keep longer as well.
The amount of hops used also has a significant effect, as hops have natural anti-bacterial properties. So there's a correlation between how bitter a beer is, and how long it will keep.
Darker beers tend to contain more anti-oxidants, which protect the beer somewhat from oxidation. (Oxidation can impart stale, cardboardy flavors.)
For weaker and/or less hoppy beers shelf life depends a lot
on how good the brewer's quality control is. Most craft/micro brews aren't pasteurized; this means they are perishable, and will eventually start to develop "off" flavors as any trace contaminants start to grow and munch on the residual sugars in the beer. It is extremely unlikely that an "off" beer will make you sick (pathogenic bacteria can't survive in beer), but it can certainly taste funky.
Macro beers are usually pasteurized or sterile filtered, and are quite shelf stable.