Can I Still Eat That?

Bailey’s Irish Cream is a dessert drink made of whiskey and heavy cream. Night after night it sits—unrefrigerated—on the shelves of bars and restaurants. Occasionally it gets poured into a thirsty Irishman’s glass. The question is: why doesn’t its milk spoil? The answer is: the alcohol acts as a natural preservative.

But that doesn’t mean you can always preserve milk with alcohol. A long time ago, the makers of Bailey’s happened to get the ratio and the combination process right, and they’re not telling what it is.

Preserving and maintaining food has been one of the human race’s biggest challenges. Imagine the feasts that must have happened back in our hunter-gatherer days, when one big buffalo kill meant available calories that had to be consumed very soon or harmful bacteria would come in.

You’ll still find the word “Preserves” or a variant on jars of jelly or jam today. That word is a reminder of one victory in long human struggle.

Drying, Smoking, Salting: We’ve Come a Long Way

Presumably after a few too many cases of food sickness (and the demands of travel), humans came up with some ingenious ways of preserving food. Most of these were drying, smoking, and salting. From a food safety perspective, most meats respond favorably to these treatments. Beef jerky, for example, does all three and can last for a mighty long time even without the vacuum seal.

But the vacuum seal is important, as is refrigeration, canning, and “chemicaling”. All of these methods represent more recents attempts to make our food last long past the kill (if meat is the subject) or the pick (if fruits or vegetables are the subject).

But few of these methods are perfect: food still goes bad. The trick is how to tell.

Sell By, Use by, Best By

We’re all used to seeing these codes on our grocery store purchases. But what do they mean? Are they reliable guides to what will make us sick and when?

The answer is no.

These codes typically have little to nothing to do with actual food safety. In fact, many of these codes have significant variance from state to state! So, a carton of eggs in California may have an “expiration date” of 2 weeks, while a carton of eggs in Arizona has an expiration date of 4 weeks, even though the eggs came from the same chicken.

Here’s a breakdown1 of what these codes actually mean:

  • Use by. This is a voluntary date placed by the manufacturer that has nothing to with safety and everything to do with the manufacturer’s idea of the quality—usually the taste—of the product in question. So, a package of heavily emulsified and preserved cookies may say “Use by December 2015.” This doesn’t mean it’ll make you sick in January, it means the manufacturer thinks it will taste best if used before January. Or, as the conspiracy theorists would claim, it means that if you haven’t used it by January, the manufacturer would like to sell you a new pack of cookies.
  • Best by. “Best by”, sometimes appearing alongside “use by,” means the same thing.
  • Sell by. This is a note from the manufacturer or provider of the product to the seller of a product.  It’s a handy gauge as to how long the perishable good will last, but “sell by” doesn’t mean “use by.” Foods will always keep in your refrigerator past that “sell by” date. If they don’t, the date was wrong. Cold comfort, huh?

Obviously, the most useful of all these is the “Sell by” date, but even this is voluntarily supplied by the manufacturer and won’t tell us how long our goods will last. In fact, the only consumable product the federal government mandates expiration dates for is baby formula. Now you know.

The USDA Product Dating Website

While the US government does not require the dating of consumable goods (except baby formula), the United States Department of Agriculture has a very handy guide to to some of the most volatile foods available. That website is available here: It’s not a bad idea to print it out and stick it on your fridge.

Tricks Of The Trade

Many ingenious folks over the years have found far more accurate ways of telling if a food is safe than looking at a nearly meaningless date. Smell, of course, is a good giveaway. But how else can we know? Well, it depends on the food.

Here’s a trick to know if your carton of eggs are really bad, even though they’re 2 weeks “past due”: fill up a large cup of water and place a questionable egg inside. If the eggs floats, throw it away. If it sinks, it’s fine. Why? As eggs age, the porousness of their shells allows air to leak in, causing spoilage. That air also causes the egg to float. If the egg does not float, that means it has not gotten to the spoiling point and it is safe to eat. Then again, some food scientists disagree with this method. Well, as our ancestors might have said, “It’s always worked for me.”

Are there other tricks you’ve heard about? Have you tested or disproved them? Do you care to share?


  1. United States Department of Agriculture. Food Product Dating.
  2. About Money. How to tell if your eggs are still good.

This article is for general educational purposes only and is not intended to be used as or substituted for medical advice.  Always seek the advice of your physician or qualified health care provider with any questions about your health or a medical condition.  Never disregard or delay seeking medical advice because of something you have read on the internet.