- Have you ever taken some milk from the fridge and you notice it's past its sell by date?

It looks okay, the sniff test suggests it smells okay, but is it?

(graphics crinkling) I'm Sheril Kirshenbaum, and on this episode of "Serving Up Science," we're taking a closer look at the dates on our food labels.

(graphics crinkling) Before we get into the nitty gritty, let's talk microorganisms and food.

Microorganisms are present in nature, and are actually an important part of some of our favorite foods like yogurt, beer, and cheese.

- [Speaker] Mmmm!

- However, certain types of microorganisms can lead to real problems.

Pathogenic bacteria causes serious outbreaks of foodborne illness, and it's typically found in what we might call high-risk items like chicken, milk, cold cuts, and sliced vegetables.

These outbreaks often make the news, from E. coli to listeria.

Then there's spoilage bacteria, which causes food to go bad and develop unappetizing characteristics, like a funky taste or odor.

But don't worry, the good news is that spoiled food won't usually kill you, although it might make you feel like you're dying.

So with all that in mind, let's talk about the purpose of food labels.

First up, we have the "Best by" date.

(graphic whooshing) This is when the products will have the best flavor or quality, but it's not an expiration date.

So if your cereal tastes a little stale, it's not the end of the world.

- He likes it.

Hey, Mikey.

- Next we have the "Sell by" date.

(graphic whooshing) This is when the store should stop selling the product, but it's not necessarily related to food safety.

So if your milk says sell by yesterday, it's probably still just fine today, unless of course, it's sour milk, and that's just utterly gross.

(person slurping) Finally, we have the most confusing date of them all, the "Use by" date.

(graphic whooshing) This is when the manufacturer recommends using the product before the quality starts to decline.

But again, it's not typically related to food safety.

If your mayonnaise says "Use by" last week, you're probably safe.

But if it's turned into a science experiment, then it's time to toss it.

- [Speaker] Eww!

- So what's the problem with these dates?

Well, for starters, they're not regulated by the government, except for infant formula.

In fact, some companies use dates just for marketing purposes.

And many folks have come to interpret all of these dates as an expiration date, meaning it's time to toss your plant-based burger, jar of pickles, or wild salmon.

(water splashing) But not so fast.

Molecular epidemiologists have found that these dates have little to do with when a food actually becomes less safe to eat.

So perhaps it's the best bet to take the more scientific approach to food safety and labeling.

Microbiologists are able to measure bacteria growth over time, and study how long microbes take to grow to dangerous levels once in contact with food.

Like drinking milk straight from the carton and putting it back in the fridge.

That can speed up the spoilage process.

And that could create a more accurate dating system that would cut down on food waste, while saving all of us money.

- Expired, expired.

Expired.

- You see, we throw away a lot of perfectly okay products that don't pose a real health risk.

With that in mind, consider the average American household currently spends over 10% of its income on food.

(cash register dinging) And wasting food means we're wasting money, water, energy, and other resources that went into producing the items.

Food production requires fertilizer and produces a lot of greenhouse gas emissions.

In addition, food waste comprises the single largest component of municipal landfills in the US and globally.

We waste about one third of the food we produce.

And over a quarter, 28% of the world's agricultural area is used annually to produce food waste.

If food waste were a country, it would rank number three in CO2 emissions, just behind the US and China.

And one reason we're tossing so much still edible food is?

An unscientific approach to dates on food packaging.

The US Food and Drug Administration reports that our current food labeling system is so confusing, it's to blame for around 20% of the food wasted in the home, and costs us consumers an estimated- (cash register dinging) $161 billion per year.

The United States isn't unique.

This is a global challenge taking place all around the world in many different forms.

The truth is, expiration dates don't always tell us much about the safety of a product, but they could.

Taking a more scientific approach to food safety and labeling could cut down tremendously on food waste while saving all of us money.

(cash register chiming) So what can we do?

Well, one thing is to be more skeptical of those dates and pay close attention to the language on the label.

For Best By and Sell By dates especially, use your senses.

Don't eat the fuzzy raspberries, and be suspicious of a mushy salad kit that emits a noxious odor.

- [SFX] Eww!

And don't drink the milk straight from the carton.

(upbeat music)