Can kefir go bad?

In this article, we will answer the question “Can kefir go bad?”, and how to tell If kefir has gone bad?

Can kefir go bad?

Yes, kefir can go bad. Because kefir is a fermented product, sometimes it might be hard to tell If it has gone bad. 

How to tell If kefir has gone bad?

Kefir is a fermented product and contains living bacterial cultures. If the kefir from two different producers differs in taste and texture, it does not mean the product is spoiled.

  1. If you notice any mold growth near the lid or on the surface of kefir, it is a clear sign of spoilage. Mold growth might be present in the form of fuzziness on the top of the bottle or pink/orange spots in the kefir.
  2. If kefir gives off a rancid or sour smell, it has gone bad. Do not confuse it with the natural fermented or vinegary smell of kefir. If it has gone bad, the smell will be too pungent.
  3. If kefir develops a clumpy texture instead of a smooth creamy texture, toss it in the bin.
  4. If the fluid has separated from kefir and is floating on the top, it has gone bad.

How to store kefir?

  1. Like other dairy products, kefir should be refrigerated at all times. Do not keep it in the door of the fridge because that area experiences most of the temperature fluctuations.
  2. Once opened, the bottle of kefir should be sealed tightly and placed in the fridge. Keeping it in the fridge slows down the fermentation process.
  3. If the original container of kefir is not resealable, pour the content into an air-tight mason jar and seal it tight before refrigerating. If you do not have any sealable container at hand, try using a makeshift seal by covering the mouth of the container with aluminum foil or plastic wrap and secure it with rubber bands.

Can you freeze kefir?

Yes, you can freeze kefir but at a cost. The texture and consistency won’t be the same after thawing. Like buttermilk and yogurt, the solids in frozen kefir will separate leaving behind fluid. It can be stirred back in by blending it in a food processor but the consistency will not be smooth and creamy.

It is recommended to use frozen kefir for smoothies and cooked dishes only where the altered texture of the kefir won’t be a big deal. You can pour the kefir in an ice cube or muffin tray or store it in an air-tight bottle or container in the freezer.

Note that freezing is not advised if your main purpose of drinking kefir is nutrition. Because the jury is still debating whether or not the culture in the kefir dies or becomes during freezing.

The shelf-life of kefir

The following table shows the estimated shelf-life of different types of kefir under varying storage conditions.

Unopened/Opened  Counter Refrigerator Freezer 
Bottled kefir milk2 hours 2-3 weeks past the printed date 2-3 months 
Homemad kefir milk1-2 days 2-3 weeks 2-3 months
Kefir grains Indefinitely Indefinitely Indefinitely
Kefir starter powder2-7 uses 2-7 uses 2-3 months

How to make kefir?

Supplies for making milk kefir

Most of the supplies listed below will be available in a milk kefir starter kit.

  • A glass jar
  • A non-metal stirring utensil
  • A breathable cover for the jar (tight-weave towel, butter muslin, paper towel, or paper coffee filter)
  • Rubber bands to secure the cover to the jar (canning jar-ring can also be used)
  • A fine mesh plastic strainer for removing the kefir grains from the finished kefir

Ingredients for making milk kefir 


  1. In a jar, pour 4 cups of milk followed by kefir grains.
  2. Cover the jar with butter muslin or coffee filter. Secure it with rubber bands or canning jar-ring.
  3. To allow the bacteria to grow, place the jar in a warm environment maintained at 68°-85°F temperature.
  4. Culture only until the milk develops a creamy and thick consistency and gives off a pleasant aroma. This can take 24 hours or less depending upon the temperature of the surroundings.
  5. When the culturing is complete, filter the kefir grains from the real product. This can be done using your fingers or by a plastic Mesh Strainer or stainless steel sieve.
  6. Store and use the kefir grains for another batch of milk.
  7. Keep the finished kefir in the refrigerator.


In this article, we answered the question “Can kefir go bad?”, and how to tell If kefir has gone bad?


Hi, I am Charlotte, I love cooking and in my previous life, I was a chef. I bring some of my experience to the recipes on this hub and answer your food questions.