Greek yogurt has become a staple in many households thanks to its thick, creamy texture and high protein content. But like any dairy product, Greek yogurt does eventually spoil. Knowing how to tell if Greek yogurt is bad.

One of the most obvious signs of spoilage is a change in color. Greek yogurt should be a pale white or off-white color. If the yogurt has turned yellow, brown, or gray, it is no longer safe to eat.

Signs Your Greek Yogurt Has Gone Bad

Here are the main signs that indicate your Greek yogurt is past its prime and should be discarded:

Mold Growth

The most obvious indicator is mold growing on the yogurt. This generally starts off as small dots or patches of furry mold. The mold may be white, green, black, or blue. If you see any mold on the yogurt, throw the entire container out.

Mold can root deeply into foods, so spoilage may be present even if you can’t see it. Don’t take chances by scraping off the mold and eating the rest. Discard the whole container.

Sour Smell

Fresh Greek yogurt has a tangy, mildly sour smell from the active yogurt cultures. However, a strongly sour or rotten odor indicates the yogurt has spoiled. A rancid or yeasty smell is also a bad sign.

Trust your nose on this one. If your Greek yogurt smells bad, don’t taste it. The sour odor means it’s past safe eating.

Change in texture

The hallmark of Greek yogurt is its ultra-thick, creamy texture. However, over time, separation can occur when water seeps out of the yogurt. You’ll notice the liquid whey pooling on top. The yogurt itself may become runny, thin, and watery.

While the nutritional value remains the same, the change in texture is a cue that the yogurt is older and closer to spoiling. At this stage, it’s still safe to eat if thoroughly stirred to reincorporate the whey. But be sure to finish it soon.

Change in Color

Fresh Greek yogurt is glossy white. As it starts to spoil, it may develop a yellowish tinge or grayish cast. Dark spots or a dull, faded color can also indicate the yogurt is past its prime.


The proteins in dairy products can start breaking down over time, causing a slimy texture. If your yogurt develops a ropy, mucus-like consistency or seems abnormally viscous, it has likely gone bad.

Off Taste

Your taste buds pick up on spoilage that your eyes and nose can’t detect. Sour, bitter, rancid, or fermented flavors point to yogurt that should be discarded. If it simply tastes bland rather than tangy and fresh, that’s another sign it’s time to let it go.

Trust your senses. If the yogurt smells funky, looks weird, or tastes off, don’t eat it.

How to Store Greek Yogurt to Maximize Freshness

How to Store Greek Yogurt to Maximize Freshness

Proper storage is key to keeping Greek yogurt fresh and extending its shelf life. Here are some storage tips:

  • Check the expiration date. This gives you an idea of how long the yogurt will stay fresh, and unopened. Avoid buying yogurt that’s close to expiring.
  • Refrigerate promptly after purchase. Don’t leave yogurt sitting out for extended periods of time. Refrigerate it as soon as possible, preferably within an hour of buying it.
  • Keep it cold. Yogurt needs to be stored at 40°F or below. Keep it in the back of the fridge, away from the door where temperatures fluctuate.
  • Allow air circulation. Don’t cram the fridge too full. Airflow helps maintain a consistent cold temperature.
  • Use by expiration date. For best quality and safety, use Greek yogurt by the sell-by or use-by date on the container. These dates account for proper refrigerated storage.
  • Check for damage. Don’t purchase yogurt containers with cracks or dents that could allow air inside. Avoid swollen packages that may indicate yeast or mold.
  • Store yogurt properly after opening. Close the lid tightly and return it to the fridge right after use. Do not store open containers on the counter or at the door.
  • Use within 5-7 days. Consume opened Greek yogurt within a week for the best flavor and texture. Discard leftovers after this point.
  • Don’t double-dip. Use a clean spoon each time you scoop out yogurt to avoid introducing bacteria.

By promptly refrigerating and using opened yogurt within a week, you can maximize its shelf life. But keep in mind that expiration dates are simply guidelines. Yogurt that’s been temperature-abused may spoil before the date on the container. Rely on your senses to determine if it’s gone bad.

How long does Greek yogurt last?

The shelf life of Greek yogurt depends largely on storage conditions.

  • Unopened yogurt: About 2–3 weeks from the manufacture date when stored properly in the fridge.
  • After-sell-by date: Can be safe for another 1-2 weeks past the sell-by date if continuously refrigerated. But quality slowly declines. Consume soon for the best flavor and texture.
  • After opening: about 5-7 days if stored in the refrigerator. Keep the lid sealed, and don’t introduce any double-dipping bacteria.
  • Freezer: You can keep yogurt safe for 2-3 months in a freezer set at 0°F. Thaw in the refrigerator before using.

Always inspect yogurt for signs of spoilage before eating, even if it falls within the date guidelines. Your nose and taste buds will let you know if it’s gone bad. When in doubt, throw it out.

Can you freeze Greek yogurt?

Yes, you can safely freeze Greek yogurt if you take a few precautions:

  • Choose plain Greek yogurt. Flavored varieties don’t freeze well. The fruit and sugars can deteriorate.
  • Make sure the yogurt hasn’t expired and shows no signs of spoilage. Only freeze yogurt that’s still fresh.
  • Store in airtight freezer containers or bags. This prevents freezer burns.
  • Portion into practical amounts for your recipes. Avoid freezing a large tub.
  • Leave about 1/2 inch of headspace to allow for expansion.
  • Apply labels with the date and type of yogurt. This avoids mystery tubs.
  • Freeze for up to 2–3 months at 0°F or below.

To use frozen yogurt, thaw it overnight in the fridge. The texture may be a bit thinner after thawing, but it is still fine to use in smoothies, baking, or savory dishes. Avoid refreezing thawed yogurt.

Freezing does slow down the activity of the live cultures. But studies show plenty of probiotics remain when yogurt is properly frozen and thawed. The nutritious protein content also stays stable. So go ahead and stock up on Greek yogurt when it’s on sale. Just be sure to freeze it immediately in well-sealed containers.

What Happens If You Eat Bad Yogurt?

What Happens If You Eat Bad Yogurt?

Eating expired yogurt that’s only mildly spoiled probably won’t make you sick. But yogurt that’s gone significantly bad can cause gastrointestinal issues like nausea, vomiting, diarrhea, and cramps.

The degree of illness depends on:

  • Microbial levels: How much bacteria grew in the yogurt as it spoiled? Consuming high microbial loads is more likely to cause illness.
  • Types of bacteria: Yogurt may harbor foodborne pathogens like Salmonella, Listeria, E. coli, and Campylobacter if cross-contamination occurs. These can all cause serious illnesses.
  • Individual sensitivity: Those with compromised immunity may become sick from lower levels of bacteria than healthy adults.
  • The amount consumed: Eating a whole container is riskier than a small taste.

In healthy adults, a small amount of mildly spoiled yogurt may cause minimal effects, like a temporary digestive upset. But err on the side of caution and discard yogurt at the first signs of spoilage. The longer it’s left out, the greater the health risks from uncontrolled bacterial growth. Don’t eat yogurt that’s slimy, moldy, smells rotten, or tastes rancid.

How to Salvage Separated Greek Yogurt

Sometimes whey separates out, leaving a watery liquid on top of the yogurt. This alone doesn’t mean it’s gone bad. Gently stir it back together, and the yogurt should be fine to eat for up to a week after opening.

But if you notice other signs of spoilage, like an off smell, mold, or slimy texture, don’t try salvaging it. The yogurt has likely spoiled. Toss it.

For future reference, here are some tips to help prevent separation:

  • Avoid temperature fluctuations. Don’t let yogurt sit out on the counter for extended periods before or after use. Keep it chilled at 40°F.
  • Check ingredients. Yogurts thickened with ingredients like gelatin, starches, or gums are more prone to separating. Go for varieties stabilized with pectin or natural ingredients.
  • Don’t overload on probiotics. Too many live cultures may cause the proteins and water to break down. Choose yogurts with six or fewer strains.
  • Give it a stir. Gently fold in any whey that accumulates to redistribute it back into the yogurt.
  • Consume within a week. Separated yogurt is still safe to eat for about 5-7 more days if stirred together. Just make sure you finish it within a week after opening.

As long as it smells and tastes okay, separated Greek yogurt can be stirred back to an even, creamy texture. But discard it at the first sign of mold or spoilage.


How to Tell if Greek Yogurt is Bad

While it’s fine to eat yogurt that’s up to a week or two past the sell-by date, it’s important to check for signs of spoilage first. Yogurt that develops mold, smells rancid, or tastes off should always be discarded. Storing yogurt properly in the fridge helps maximize freshness. But remember to rely on your senses, not just the date on the container, to determine if your Greek yogurt has gone bad.


Can you eat yogurt after the expiration date?

It’s generally not recommended. The expiration date is an estimate of when the yogurt will start deteriorating in quality and safety. Eating yogurt more than 1-2 weeks past this date is risky.

Can I scoop mold off yogurt?

No, the mold roots can penetrate deep into the yogurt, so scraping off the surface mold doesn’t make it safe. Even a tiny amount of mold signals that bacteria have multiplied and toxins may be present. Discard the entire container.

Does boiling spoiled yogurt make it safe?

No, boiling won’t destroy the bacterial toxins produced as the yogurt spoils. These toxins can still make you sick. Always throw out yogurt once it’s gone bad.

Why does yogurt get slimy when it spoils?

The healthy bacteria and proteins start breaking down as the yogurt ages. This causes a slimy, viscous texture from the decomposing components. Slimy yogurt should never be consumed.

Can I substitute spoiled yogurt for sour milk in baking?

It’s generally not recommended because of food safety concerns. Spoiled yogurt contains uncontrolled levels of bacteria that could grow during baking. Use fresh yogurt or commercial buttermilk instead.

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Roger Walker

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