Drinking "Expired" Beer

Is it safe to drink beer six months past its “drink by” date? What about its flavor?

The simple answer is yes, the beer is still good insofar as it is safe to drink. Since most beer is either pasteurized or filtered to eliminate bacteria, it’s extremely resistant to spoiling. How the beer will taste is another matter. For a taste test, we met with Grant Wood, senior brewing manager of the Boston Beer Company, to sample fresh lager next to one that had seen its first anniversary. (Typically, the drink-by dates on beers are four to six months out; this is based on how long the brewer thinks the beer can retain fresh flavor.) The difference was dramatic. While the fresh lager presented bright hops flavor and refreshing bitterness, the year-old bottle was distinctly malty, sweet, and, according to most tasters, “flat.” The difference was even more pronounced when we repeated the tasting with a bottle that had been forgotten in a basement since 2004.

According to Wood, the explanation is twofold. First, all beer contains a minute amount of oxygen, and as the aroma and flavor compounds found in hops oxidize over time, those compounds dissipate. (Conversely, certain aromatic compounds increase with prolonged exposure to oxygen, resulting in sweet, sherry-like flavors.) Second, the speed of these reactions depends on the alcohol content of the beer and how it’s stored. Beers with more alcohol by volume have a longer shelf life, as do those that are refrigerated.

The lesson: To enjoy beer at its finest, buy it cold, store it in the fridge, and drink it before the date on the bottle.

Beer consumed after the "best by" date (often located on the side of the label) tastes flatter and more sweet.

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