Food preservation

Can Kefir Go Bad?

Kefir is a popular dairy product that is lauded for its numerous health benefits. Most people drink kefir because it has probiotic properties that regulate digestive functions and enhance their immune system.

Manufacturers make kefir by fermenting milk with kefir grains. Kefir grains are live creatures that advance the development of probiotics and healthy bacteria.

Can kefir go bad? The answer is yes. Kefir eventually goes bad because of the presence of bacteria. 

Since kefir is a fermented product, it may be difficult to tell if it has gone bad. That is where this article comes in.

We will discuss all the relevant information about kefir, including its shelf life, signs of spoilage, what happens if you consume old kefir, and how to store it properly. Additionally, we will discuss freezing kefir and how to make homemade kefir.

How Long Does Frozen Milk Last After Thawed? Click to Read.

Can it go bad?

Although kefir is a fermented product, it can, and will, eventually go bad.

Kefir’s shelf life significantly depends on various factors, including; whether it is homemade or store-bought and how it is stored.

If you are doubtful about it being safe to consume, check for signs of spoilage.


Kefir Shelf Life

Like most fermented products, kefir has a relatively long shelf life because of its natural, healthy bacteria. With time, these bacteria may cause kefir to spoil.

Usually, kefir comes with a best-by date on the container. It will last for up to seven days past the best-by date regardless of whether or not you have opened the container. 

Note that the flavor of kefir becomes stronger as it gets closer to the best by date. Typically, its taste would be too strong a week past the date since fermented products evolve before they spoil. Homemade kefir will last for three weeks if you store it properly.

If you intend to consume kefir that is past its best by date, ensure you check for signs of spoilage beforehand. Consuming spoiled kefir can make you sick.

Note that the periods above are estimates. Your kefir can go bad sooner or later than the estimated period.


Signs that kefir has gone bad

If you are doubtful about whether or not your kefir has gone bad, check for the following signs;

  1. Rancid smell- kefir shouldn’t smell rotten or sour. If it does, the chances are that it has gone bad.
  2. Mold- check the surface of your container for any mold growth or orange spots. If it’s there, discard the kefir as it is not safe for consumption.
  3. Heavy separation- if your kefir has a layer of liquid at the top, it is highly likely that it has gone bad.
  4. Overly sour taste- naturally, kefir has a slightly sour taste, but if the sour taste becomes too potent, it may be a sign of spoilage. Discard it if you find it too overwhelming.

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Can you safely consume old kefir?


There is a high chance that kefir which is a few days past its best by date, won’t harm you as long as it is still in good condition and doesn’t exhibit any signs of spoilage.

It would be best if you examined the kefir before consuming it. Ensure that it doesn’t have any mold because mold can make you sick.

Note that old kefir may taste somewhat sour.

Also, Check out : A list of Suitable Whole Milk Substitutes. Here.

How to properly store kefir


Since kefir is a dairy product, you should store it in the fridge. Keeping kefir in the refrigerator ensures that it remains safe for consumption and slows down the fermentation process.

The kefir will continue fermenting slowly and steadily while in the fridge, hence the long shelf life.

When you open the container, ensure that you seal it tightly before putting it back in the fridge.


If the kefir you bought came in a non-resealable container, transfer the kefir to a mason jar before storing it in your fridge. This way, the kefir will retain its quality.

Note that you shouldn’t leave kefir at room temperature for an extended time. It will quickly turn unpleasantly sour and may no longer be safe to consume if you do.

I recommend placing kefir at the farthest corner of your fridge, where the temperature is stable. Fluctuating temperature tends to interfere with its quality and shelf life.

How Long Does Milk Last? Click to Read.

Can you freeze kefir?


If you want to extend kefir’s shelf life, you may wonder whether freezing is an option. You can freeze kefir. However, most manufacturers advise against it because kefir doesn’t freeze well.

Freezing kefir alters its quality and consistency. Like most dairy products, the liquids and solids in kefir tend to separate when you freeze and thaw it. Therefore, the texture of thawed kefir won’t be the same as that of regular kefir.

The change in texture is inconsequential if you plan to use it in baking or cooking, but if you consume it on its own, the kefir will be unpleasant.

You can try to fix the consistency by blending the kefir. Although it won’t be as creamy as before, it will be palatable.

I suggest freezing kefir in ice cube trays. This way, you can quickly thaw the amount you need when you need it. To defrost kefir, you should place it in your refrigerator overnight.

How to make homemade kefir


To make homemade kefir, you will need;

  • Four cups cow/goat milk.
  • Two teaspoons of active milk kefir grains
  • Glass jar
  • Stirring utensil (non-metal)
  • Coffee filter/butter muslin.
  • Rubber band.
  • Mesh strainer (plastic).


  1. Transfer your milk to the glass jar, then add the kefir grains.
  2. Use your coffee filter or butter muslin to cover the jar and secure it with a rubber band. You can use any other breathable cover in this step, including a paper towel, a tight-weave towel, or a paper coffee filter.
  3. Place the jar in a warm environment. The temperature should be between 68-85 degrees Fahrenheit. This will allow the bacteria to grow.
  4. Culture the mixture until its consistency turns creamy and its aroma pleasant. This process may take approximately 24 hours.
  5. Use a mesh strainer to filter the grains from the kefir.
  6. Store your finished product in the fridge.


Kefir is a nutritious dairy product that has numerous benefits. Like other dairy products, it eventually goes bad.

Usually, store-bought kefir lasts for up to seven days past the best by date. Check for any signs of spoilage if you are unsure of its quality.

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