Food Expiration Dates: What Do They Really Mean?


food-expiration-datesAre you one of those people who pour the milk down the drain on the expiration date? Expiration dates on food products can protect consumer health, but those dates are really more about quality than safety, and if not properly understood, they can also encourage consumers to discard food that is perfectly safe to eat.A recent poll of more than 2,000 adults showed that most of us discard food we believe is unsafe to eat, which is a good thing, of course, but it is important that we understand what food expiration dates mean before we dump our food — and our money — down the drain or into the garbage. On average, in the U.S. we waste about 14% of the food we buy each year. The average American family of four throws out around $600 worth of groceries every year.

Which five foods are most often feared as being unsafe after the printed date? According to, we are most wary of milk, cottage cheese, mayonnaise, yogurt, and eggs, and the site offers these helpful explanations:

•Milk: If properly refrigerated, milk will remain safe, nutritious, and tasty for about a week after the sell-by date and will probably be safe to drink longer than that, though there’s a decline in nutritional value and taste.

•Cottage cheese: Pasteurized cottage cheese lasts for 10-14 days after the date on the carton.

•Mayonnaise: Unopened, refrigerated Kraft mayonnaise can be kept for 30 days after its expiration date or 3-4 months after opening, the company told ShelfLifeAdvice.

•Yogurt: Yogurt will remain good 7-10 days after its sell-by date.

•Eggs: Properly refrigerated eggs should last at least 3-5 weeks after the sell-by date, according to Professor Joe Regenstein, a food scientist at Cornell University. Note: Use of either a sell-by or expiration (EXP) date is not federally required, but may be state required, as defined by the egg laws in the state where the eggs are marketed.

The “Use-By” Date

The “use-by” or “best if used-by” date indicates the last day that the item is at its best quality as far as taste, texture, appearance, odor, and nutritional value. The decline after that is gradual. The use-by date refers to product that has not yet been opened.

The “Sell By” Date

The “sell by” date is not really a matter of food safety, but a notice to stores that the product should be taken off the shelf because it will begin to decline in quality after that date.

The Law

From the U.S. Department of Agriculture (USDA): “Product dating is not generally required by federal regulations. However, if a calendar date is used, it must express both the month and day of the month (and the year, in the case of shelf-stable and frozen products). If a calendar date is shown, immediately adjacent to the date must be a phrase explaining the meaning of that date such as “sell-by” or “use before.”

There is no uniform or universally accepted system used for food dating in the United States. Although dating of some foods is required by more than 20 states, there are areas of the country where much of the food supply has some type of open date and other areas where almost no food is dated.”

Food-Borne Illness

Cross-contamination and unsanitary conditions are a primary cause of food-related illnesses, whether it occurs in the home or in a restaurant, and this is independent of any expiration date. The leading culprits are:

•Improper hand-washing prior to food preparation.

•Storing food at the wrong temperature.

•Cooking food to an inadequate temperature.

•Cross-contamination (raw meats that come into contact with salads, for instance).

•Improper washing of fresh produce.

The Yuck Factor: Common Sense Approach to Food Safety

Aside from any expiration date or lack thereof, if a food item is moldy or if it smells and looks spoiled, err on the side of caution. If it makes you say, “yuck,” throw it away.



  1. I was once lectured sternly by a friend, (a Teimani who grew up in the poverty of early state EY) that “there is no such think as spoiled milk!”
    He them rattled of a recipe for some pancake with eggs, spoiled milk, and hot peppers.
    Milk will start curdling on the way to becoming cottage cheese, ideally in a controlled environment at 90F. In spoilage, only the particular bacterial culture is a suspect of being unsafe or unpalatable. The safety is remedied by cooking, and the taste is fixed by the additions. The proteins remain the same, and in places and times where protein is scarce and expensive, “there is no such thing as spoiled milk”

  2. It seems that some heimish brands just started putting “sell by” dates. Many of them use mysterious codes. They should all put real dates so that we don’t buy old spoiled food.

  3. I’m not sure how well researched this article is, and I am sure there are opposing opinions to the few authorities cited. Please be careful everyone.