We’ve all been there: You open the fridge, reach for the milk, and notice the date on the carton says it expired yesterday. You gingerly sniff the carton, fully expecting to be overwhelmed by noxious fumes but instead all you can smell is . . . milk.
According to University of Minnesota food scientist Ted Labuza (who spoke to Slate), perishables like milk and meat have a three- to seven-day grace period after the expiration date, assuming you are a normal person and store said perishables in the fridge and not, say, the sauna. The fact is, the “sell by” date that appears on that questionable gallon of milk serves as a guideline for stores on when they should pull products from their shelves — not when you should indulge in a last sip. Rather than being an indicator of the product’s safety span, the date implies when a food’s quality — its taste, aroma and appearance — would be at peak conditions.
What’s even more confusing is the lack of consistency in “open dating” descriptors and regulations on labeling. In addition to “sell by,” certain products contain “best if used by (or before),” to indicate peak quality, “use by,” to establish a finite don’t-ingest-after-this-date or simply the jumble of numbers that is a “closed date,” for those long-living shelved goods.
The U.S. Food & Drug Administration requires that an expiration date appear on only infant formula, which must contain the quantity of nutrients described on its label. Milk — so widely known for its spoiling — is not uniformly regulated, but is handled on a state by state basis. Manufacturers perform stress tests on milk to determine an expiration date, ranging from 15 to 21 days post-pasteurization. Only certain states, indicated in the chart below, mandate a specific “sell by” date, with a handful falling short of that 15-day manufacturer-determined minimum.
New York City is notoriously the only city which contains its own regulation on milk dating; there are no requirements for the state at large. The debate rages as to whether this separate date is due to longer unloading times during delivery or improper store storage temperatures. But if you’ve ever tried to move into an apartment building in Manhattan at 4:30pm on a weekday like one of our Slashfood writers, you’d probably guess it’s the former.
With all this talk about milk, you’re probably wondering how to factor in expiration dates on all those other perishable foods you buy? Pay close attention to meat, which should be cooked or frozen within two days of purchase. If you freeze that ground beef or rack of lamb, be sure to cook them within 3 months or 12 months, respectively. Cold cuts, which can contain an organism called listeria, should be consumed by their use by dates.
Other foods offer some more wiggle room, though. You’ll get a few weeks out of hard cheeses — which is good to know, considering how stinky they can be outright. Interestingly, the United States Department of Agriculture found that eggs refrigerated at an optimal 27 degrees are safe for up to four to five weeks past their expiration. As you’d expect, you’ll have the most leeway with dry goods. Pasta and rice is fine for a year. Unopened packages of cookies are good for a few months (though we wonder who has packets of cookies that sit around unopened for months?) and canned goods are safe for at least five years: perfect if there’s a major catastrophe that keeps you housebound for . . . years. But beware of cans that are dented or rusted, as rust signifies tiny pin holes that can provide an entrance point for bacteria.
In the end, the best “use by” detector is planted firmly in the middle of your face. If it smells suspicious, it’s best to chuck it; if it smells okay then it’s usually fine.