Americans waste a lot of food, either 40 percent or 25 percent of that which we come in contact with, depending on the source. Some experts, such as Maria Corradini, a food scientist at the University of Guelph, blame, in part, a confusing food packaging system (Sell By, Best By, Use By) that prompts people to throw out food that’s still safe to eat.

“In general, none of these labels is directly related to food safety,” she says.

Even the Use By labels applied to perishable dairy products are estimates and can’t take into account whether a half-gallon of milk spent time sitting in a warm stock room before you bought it. On the other hand, the same jug may have sat in a very cold refrigerator (first in the store and then at home) and so could last up to two weeks beyond its Use By date.

Instead of relying exclusively on a label, experts say to give the milk and other perishable products a good old fashioned whiff and feel for slimy textures and other signs.

Dry goods often come with a Best By label, after which they may have less flavor or nutritional value but are typically still safe to eat, according to Corradini.

“In most cases, they are not going to harm you,” she says. “There is no need to waste them.”

This video originally appeared in Knowable Magazine, an independent journalistic endeavor from Annual Reviews. You can view the original here.