The truth about food expiration dates:

How helpful are food expiration dates? Many of them are actually quite confusing...

The dates, for one, mean quite different things. For instance, "sell by" is more a guide for the store to know how long it can display a product for sale. The "best before" or "best if used by" date refers to a quality or flavor of the food. "Use by" works more like an expiration date, similar to that on medicines, and taking them after the date is not recommended.

Worse, some dates can actually be quite misleading. Few folks, for instance, know when they buy meat, that even if the sell-by date is five days away, the refrigerator at home usually isn't cool enough to keep the meat fresh for more than two days. Usually raw meat is kept around 30 degrees Fahrenheit, while the home refrigerator's temperature is set around 40 degrees to keep other things in the fridge (like vegetables) from freezing. So, food safety experts suggest that whether it's ground meat, or a pound of steak, or chicken, consumers either eat or freeze it within two days of buying.

Of course, even frozen meats don't last forever. Some, like ground beef, need to be consumed within three months of being frozen. "Ground meat spoils more quickly because there's more surface area for bacteria to grow on," says Tufts' Goldberg.

Many other foods, like potato chips or mayonnaise, that have oils or fat will go rancid and will taste bad before they can breed bacteria and hurt people. Surprisingly enough, eggs have a pretty long shelf life and can last as long as five weeks after the sell-by date if refrigerated properly.

Ultimately, most of these labels should be used more as a guide, rather than a hard and fast expiration date. And the confusion might even be a little deliberate on the part of the government.