How to know if yogurt is spoiled?

In this brief article, we will answer the question ‘’How to know if yogurt is spoiled’’. We will also discuss the health consequences of eating spoiled yogurt and  the proper way to handle your yogurt to avoid spoilage and prolong its shelf life.

How to know if yogurt is spoiled?

You will clearly know if your yogurt is spoiled when it tastes sour with a rancid smell and molds swimming in the watery part of yogurt. It is better to smell your yogurt if you are unsure because fresh yogurt has a creamy and fresh smell. 

You should never eat spoiled yogurt as consuming it increases the risk of getting a serious foodborne disease by harmful microorganisms and their toxins (1-5). If you are not sure if your yogurt is spoiled, you can check the following sings:

  1. Excess liquid in the container:If there is excess liquid oozing out of the yogurt then throw it away because chances are the yogurt is too old and has bacteria living in it.
  1. Moldy yogurt: Moldy yogurt is a very clear sign that you need to immediately throw away the yogurt.  Molds produce dangerous mycotoxins that can make you very sick (6), therefore, don’t consume it.

You might even see black mold on some parts of the yogurt but it is better to discard the whole pack away instead of only getting rid of the bad parts. 

  1. Sour taste:A sour taste means that the yogurt is spoiled. Fresh yogurt is creamy and tastes very plain, neither sweet nor salty. 
  1. Discoloration of the liquid in yogurt: If you find that the water oozing out of the yogurt is brown or turning yellow then the yogurt is probably spoiled. Refrain from using it at all. 

Does liquid on the surface mean that yogurt is spoiled?

No, it does not always mean that the yogurt is spoiled. Use your sense of smell and taste to check whether the liquid that is separated has brown color and a sour taste or not. If so, then it is spoiled. 

If you have store-bought yogurt then liquid on top means that the yogurt is old now.

Normal liquid which separates from yogurt is fine and you can still eat that yogurt. This is more common in homemade yogurts as compared to the store bought ones. If the liquid does not smell off or taste bad then mix it with the yogurt before eating it. 

How to tell if unopened yogurt has gone bad

If unopened yogurt is way past the expiry date, then chances are that it might be spoiled. In addition to this, if you see molds after you open it or find liquid heavily separated from yogurt with an off smell then the yogurt has probably gone bad. 

Can you get sick from eating spoiled yogurt?

Yes, consuming spoiled yogurt can present health hazards due to the existence of different harmful microorganisms and their toxins (1-5).

Here are some examples of the most common pathogens that can be found in spoiled yogurt and induce foodborne illnesses:

  1. Staphylococcus aureus: S. aureus is a common bacterium that can cause food poisoning when its toxins are present in food (1). Symptoms may swiftly arise, including nausea, vomiting, stomach cramps, and diarrhea. Ingesting yogurt contaminated with S. aureus and its toxins can lead to severe illness.
  1. Listeria monocytogenes: Listeria contamination is particularly concerning for vulnerable populations (2) and lead to symptoms like fever, muscle aches, nausea, diarrhea, and, in severe cases, can progress to meningitis or bloodstream infections.
  1. Specific strains of E. coli: E. coli O157:H7 can cause severe food poisoning, with symptoms including diarrhea (often bloody), abdominal pain, nausea, and vomiting (3). 
  1. Salmonella: This bacterium can lead to salmonellosis, manifesting as diarrhea, abdominal cramps, fever, and vomiting (4).

While yogurt is not a typical source of E. coli and Salmonella contamination, cross-contamination during handling or inadequate sanitation practices can result in their presence.

Iti is highly recommended to refrain from consuming spoiled yogurt to minimize the risk of foodborne illnesses. You should always check for the signs of spoilage previously described before consumption. 

What should you do if you suspect you have eaten spoiled yogurt?

If you suspect that consuming spoiled yogurt has made you ill, it is crucial to assess your symptoms, including nausea, vomiting, diarrhea, abdominal pain, fever, or discomfort (7). 

You should also stay hydrated by drinking fluids and rest while monitoring your condition, as most foodborne illness symptoms typically resolve within a few days (8). 

However, if symptoms worsen, persist, or become severe, it is important to seek guidance and treatment from a healthcare professional. 

Finally, it is important that you consider reporting the incident to local health authorities or food safety agencies to promote public safety. 

What is the shelf life of yogurt?

Check the date on the packet, it mostly lasts for 3 to 5 days after the best-by date but starts to get yellow or starts to leak water if you keep it for too long. 

Once opened, you can consume it fresh for a week while keeping it refrigerated.

Of course there are yogurts which have preservatives that increase the shelf life and so will last longer but it is much more healthier to buy the ones which don’t have preservatives.

How to store yogurt to avoid its spoilage?

Keep it inside your refrigerator at all times! This means that as soon as you bring it back from the supermarket, store it in your fridge to protect from any kind of bacteria or mold. 

Leftover yogurt should be shifted to an air-tight container with a seal before putting it inside the fridge.

You can keep it in the fridge door but make sure that you don’t open the door too often and especially when it is too hot. Yogurt that is not tightly sealed will have access to many harmful microorganisms even if you store it inside the refrigerator. 

Is it okay to freeze yogurt?

Yes you can freeze yogurt but keep in mind that the texture will not remain the same and there will be much more liquid than normal because of the freezing factor. 

If you use yogurt in salads then it is better not to freeze it but if you want to cook the yogurt then freezing will do the work for you.


In this brief article, we answered the question ‘’How to know if yogurt is spoiled’’. We also discussed the health consequences of eating spoiled yogurt and  the proper way to handle your yogurt to avoid spoilage and prolong its shelf life.


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