Sell by, use by, best by: Do you know the difference between expiration date codes?

WASHINGTON — You probably check the use-by, sell-by and best-by dates on foods before you buy them, and when you’re deciding whether to toss them. But you might not know what they mean — or that they don’t mean the same thing at all.

Bob Brackett, the director of the Institute for Food Safety and Health at the Illinois Institute of Technology, says that the sell-by date is the least-important one — it’s really for the seller, to let them know when the food in question has reached the two-thirds point of its shelf life.

The best-by date is the day on which the quality of the food starts declining, Brackett says — noting that quality and safety are not the same thing.

And the use-by date is, in fact, the date by which you should eat the food. Again, it’s a question of quality, not safety, unless the label or stamp is followed by the words “for safety.” Brackett does say, though, that after the use-by date, quality goes down so quickly that safety could soon be a problem. If you’ve opened the package, Brackett tells Women’s Health, that makes things a little less precise because of the chance that the food has been contaminated.

Brackett adds that smell, color and texture aren’t the only indicators of whether something has gone bad: The organisms that cause disease are invisible, and they don’t cause the kind of spoilage you can detect.

So why can’t all food have one date or the other, for consistency’s sake? That’s a good question, Brackett tells Women’s Health. Some people are pushing for a standard requirement, but there’s no rule on which date to label for, so manufacturers can do what they want.

This content was republished with permission from CNN.

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