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Nerdy Science in the Kitchen

How Long Does Yogurt Last Outside the Fridge?



That yogurt looks good. But is it? Know for sure.
That yogurt looks good. But is it? Know for sure.

With everyone’s busy lives, sometimes things get left out of the fridge. I know I’ve been guilty of this. Once I left for work in the middle of summer and I didn’t double check my kitchen counter. I came home that night to a butter dish covered in a liquid mess where the butter used to be.

Some foods are obviously ruined when left out. With others it can be harder to tell. Is it still safe? Is it okay to eat for now, but will go bad sooner because it was left out for a while?

Yogurt, one of my personal favorite breakfast foods, is one of those that sometimes it’s hard to tell.

Basic rules

Now, if you leave any kind of dairy out all day in the heat, I think pretty much everyone knows not to eat that. We all know dairy usually needs to be refrigerated, and leaving yogurt out on the counter all day definitely violates that rule.

But what if you run out to the grocery store to pick up more eggs and come back to find your yogurt sitting out. It hasn’t been too long… should you risk it?

The basic rule is “under two hours”. If your yogurt has been sitting out for two hours or less, you’re probably good to go. You can return it to the fridge and not worry too much.

Now, if it’s an especially hot day, over 90 degrees Fahrenheit (like the day with my butter mishap), that “safe time” goes down to only about an hour.

Heat helps bacteria multiply. The hotter it is, the less time it’ll take for your yogurt to go bad.

Not that you asked… but here’s the butter dish I love at Amazon.

Why does it matter?

Obviously no one wants to eat food that has gone bad.

But did you know that it’s actually surprisingly common? 100,000 Americans go to the hospital with food poisoning each year. That doesn’t even count all the people who just suffer through minor food poisoning at home.

In fact, even scarier is that 3,000 Americans die each year due to food-related illnesses– essentially from eating food that has gone bad. Now, while eating sour yogurt isn’t likely to send you to the hospital, it can actually carry some pretty nasty sicknesses.

E. coli, salmonella, and listeria can all grow in yogurt if it isn’t stored properly. Those are all illnesses you don’t want to mess around with!

Plus, a lot of the things that are likely to make you sick will be invisible. You won’t see mold or discoloration in the yogurt, but the bacteria will be growing. That’s why it’s important to toss out yogurt that has been left out too long, even if it looks or smells alright. You might be accidentally eating harmful bacteria.

Blueberries and yogurt. It gets no better.
Blueberries and yogurt. It gets no better.

Things to know

Here are a couple of other things to keep in mind:

  • Fruit and sugar are actually great for bacteria. They make it easier for it to grow and more likely for your yogurt to go bad more quickly.
  • Once yogurt has sat out for 1-2 hours and been returned to the fridge, even though it’s still good, it will probably be good for less time. You should plan on eating it sooner than the expected expiration date.
  • Opened yogurt stays good for 7-21 days, depending on the kind, how much sugar is added, the temperature in the fridge (it should stay around 40 degrees F), etc. Don’t try to stretch that shelf life just because it looks okay. Like I mentioned above, sometimes you can’t see what’s growing inside!
  • If you ever notice discoloration, mold, or changes in your yogurt’s texture (it gets runny or strangely solid) do yourself a favor and just throw that whole carton away. It isn’t worth the risk.

Ever think about making your own yogurt?
Here’s a pretty awesome machine at Amazon.

Tips for keeping yogurt good

I know all this might make it sound like yogurt is very easy to get sick from. And you might wonder if it’s even worth it. Don’t worry too much.

As long as you keep it in the fridge for the most part, and eat it within the given expiration date, you’re in good shape for a healthy, tasty snack! I love eating yogurt, especially with granola and fruit for breakfast. (Though sometimes I crave a good pancake or egg muffins)

Now you know some rules for when to throw it out and buy yourself a new carton. In this case, it’s better to be safe than sorry.

When you’re ready to make your own yogurt, get a good thermometer. Read my review of the best ones for making yogurt.

Kitchen Professor author
About the Author: Alexis DeAnda

Alexis DeAnda is a food fanatic, library card user, and cast iron hunter, in that order. She has been cooking for anyone that will taste it ever since her mom let her make doughnuts on Saturday mornings at the age of 7.

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