“You can’t drink that milk! The date on it is yesterday!”

Who has heard that? Or was it you who said it?

The dates printed on milk jugs are probably some of the most misunderstood sets of numbers in the grocery store. One of the most common arguments people have at home is whether food should be thrown out because the date has passed. Date labels such as “Sell By,” “Use By” and “Best Before” are very confusing, contributing to about 130 billion pounds of food waste—more than $160 billion—every year. Think about how much money that is!

Aside from infant formula, product dating is not generally required by federal regulations. While dating of some foods is required by some states, there are areas where almost no food is dated.

A “Sell By” date is found on perishable foods like meats and milk. This tells the store how long it should be displayed. It is not an expiration date. Typically, one third of the product’s shelf life remains after this date if the product is kept refrigerated at home. That means milk—if it has been refrigerated at all times, has not left out on the counter and has not been drunk directly from the container—will usually be drinkable for about one week after the “Sell By” date.

Egg carton dates may have a “Pack Date” or a “Sell By” date. The “Sell By” date will not be greater than 45 days after packing. Refrigerated eggs—in their carton, and not in the door—can still be used for three to five weeks after that date.

A “Use By” or “Best By” date is a recommendation for best flavor or quality—it is not a safety issue. These are normally found on shelf-stable products such as canned or boxed goods or condiments. Foods age in different ways. For example, frozen meat will not become unsafe to eat if it is kept frozen, but that doesn’t mean it won’t change. Freezer burn will affect the quality and texture of the meat, and could make it unpalatable. Foods such as cookies and crackers will also be affected by time. The fat in the cookie will react with oxygen and become rancid, while crackers will absorb moisture from the air and become stale. They will taste “off,” but should not make you sick.

An “Expires On” date, however, is about safety. Only a small group of foods have expiration dates. Infant formula and some baby foods, for example, are required by federal regulations to have an expiration date. Other foods that should have an expiration date include ready-to-eat foods such as deli items and prepared sandwiches. These foods may contain harmful bacteria and are not cooked before they are eaten.

Expiration dates are about safety, while “Best By” dates are about taste, texture and appearance. To save money—and reduce waste at the grocery store and the curbside—your best bet in deciding if something is still good is to use your senses. Look at it, smell it, feel it, taste it. iBi

Lisa Strickland is owner and president of Daily Laboratories, a private, ISO-certified microbiology laboratory serving a variety of industries. For more information, visit dailylaboratories.com.