Here’s a good problem to have: Let’s say the barbecue you’d planned fell through and you’ve got a couple of crates of beer on your hands that now will take nearly forever to drink. How long will it keep? The short answer is: longer than you may think. Although beer, in contrast to wine or spirits, is one of the few alcoholic beverages requiring a best-before date on the bottle or can, you don’t have to pour it down the drain as soon as it’s expired, says Daniele Krehl, a nutrition expert for the consumer advice centre in Bavaria, Germany. “The best-before date is simply the brewer’s guarantee …