Milk. It’s great on cereal, with cookies, and in your mouth when you’ve eaten too many peppers, but horrible when you pour some and chunks fall into your glass. It’s easy tell when milk is obviously expired—when it looks more like yogurt than liquid—but what about before that? How do you know if you’re throwing away milk too early—or too late?

You may think you can tell if a milk is still good by the sniff test, or by a quick taste test, but unless your superpower is a heightened sense of smell, the smell test isn’t all that accurate until quite a bit of time after milk has gone bad. All milk cartons have a sell-by or expiration date stamped on them, and because we all hate throwing away food, we treat these as more of a suggestion than a rule. But is that right?

We asked some food safety experts whether or not it’s safe to drink milk after the printed expiration date. And if so, for how long? Here’s what they said.

The sell-by date and the expiration date

Peter Bonet of the Lincoln Culinary Institute says the sell-by date is the date in which your supermarket needs to stop selling that particular carton of milk. The expiration date is the date you should, technically, throw that milk away, provided you stored the milk correctly. So it’s actually a good guideline to go with, despite what your cheap parents may have had you believe.

Drew Harris, chair of the New Jersey Public Health Institute, says that these dates aren’t actually standardized like you think they would be.

Fresh milk is regulated by each state and not the feds. So, there is no one standard for calculating “sell-by” dates. Some states ban the sale of raw milk completely, which is a much more likely to be contaminated. There’s a reason Dr. Pasteur invented his process for disinfecting milk.

He points to a paper from the Cornell University Milk Quality Improvement Program (it’s a thing) that says that shelf-life is determined by refrigerating milk at marginal refrigeration temperatures—about 45º F—seeing how much bacteria is in the milk after X amount of days. Bonet recommends at least setting your refrigerator to 38º F or below.

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