Enjoy it now!

When you shop for beer, do you check each can or bottle for a date indicating when it was made, or when it will be past its prime? If not, you probably should.

According to many beer aficionados, freshness is so important to many beers that undated bottles—especially dusty ones—or those with best-by dates that have expired, should be left on the shelf. If a bottle or can is undated, how can you tell? You really can’t.

It’s an issue that has been gaining attention for a few years, and today, in fact, most breweries print a date on their packaged beer. It’s the breweries that still don’t that irk some in the industry. “Undated and outdated beer is the undiagnosed high blood pressure of craft beer,” says Marty Jones, a publicist for the equipment lender Brewery Finance.

While many beer styles, especially those higher in alcohol, can get better with time, freshness is especially important for beers characterized primarily by their hops. The aromas of hops fade and, eventually, disappear relatively quickly. An IPA, for instance, that has spent a year or more unopened is liable to taste like a malty brown ale, with the IPA’s signature fruit and flower notes lost.

Off-flavors can even develop from the deteriorated hop compounds—most notoriously the flavor of dank cardboard. (Funny, isn’t it, how we compare flavors to things that few sane people have ever eaten?)

“A hoppy beer loses its wow factor when it gets older,” says Novato homebrewer Kevin McMahon. “A fresh, hoppy brew—there’s not much like it.”

He says that a reliable rule of thumb calls for drinking high-alcohol beers after a few months or more, and consuming hoppy beers fresh.

But it isn’t necessarily that simple. Aromatics are the first component to fade from an aging beer, and among IPAs, McMahon explains, some can tolerate the passage of time more gracefully. New England-style, or hazy, IPAs—which contain less bitterness but more potent aromas—are more susceptible to the wear and tear of time. West Coast-style IPAs—famed for their bold hop flavors—are hardier. McMahon says he will drink West Coast IPAs as old as six months.

Still, the younger the better, and the call for fresh IPAs prompted Stone Brewing Co., in 2012, to launch an IPA series called Enjoy By. These recurring releases are packaged and stamped with a drink-by deadline (the date is actually part of the beer’s name) of just a few weeks, and they are shipped within about a day of being brewed.

“We feel that it respects the consumer, and our beers, for people to be fully informed,” says Greg Koch, the founder of Stone. When the date is clearly printed on the bottle, it allows the consumer “to select the freshness level that they want.”

Brewers are hardly required to date their beer—probably because there are no significant health risks associated with consuming “expired” beer. Still, the Brewers Association, the Colorado trade group representing United States breweries, recommended in February that they do it.

“[I]t is in the best interest of craft brewers, distributors, importers, and consumers that all beer from small and independent craft brewers be identifiable by some form of a date or lot code,” the BA says on its website.

This has the added benefit of helping distributors identify beer that, for example, has been recalled for safety reasons, like the time in 2008 when the Boston Beer Co. recalled thousands of 12-ounce bottles of Samuel Adams that the brewery determined to be at risk of shattering.

For the most part, drinking beer is a relatively risk-free activity, and batch dates are most useful for making sure we don’t pay money for a fresh IPA and wind up with a malt bomb.