What to Do with Over-Fermented Kefir: 11 Easy Ways to Use it

A jar of milk kefir with a blue spoon on top that has kefir grains on it.

Fermenting milk kefir is not always easy. If left too long it will over-ferment, look weird, smell bad, and taste sour. The good news is that your kefir is not ruined, and there are still good uses for it.

As long as your kefir has not been over-fermenting too long, there is still hope. Most of the time kefir grains won’t go bad from just a couple of days of over-fermentation. An ounce of prevention is worth a pound of cure, so try to avoid over-fermentation as much as you can!

In this article, I will tell you about 11 different ways to use over-fermented kefir that will help you make good use of it so it won’t go to waste. I have also added some tips on how to prevent milk kefir from over-fermenting.

TIP: Read my article about water kefir vs milk kefir to find out exactly what the difference is and which is best!

11 Uses for Over-Fermented Kefir

Fermenting kefir properly depends a lot on the temperature. Hot temperatures speed up the process, and cold temperatures slow it down, so it’s easy to misjudge the timing and over-ferment kefir. Over-fermented kefir tastes very sour and can be hard to drink.

Over-fermented kefir doesn’t need to be thrown out, it can be used in other ways. Here are 11 uses for over-fermented kefir:

#1: Add More Kefir to Make It Mild

Over-fermented kefir can be added to a fresh batch of kefir to reduce the sourness. Whisk or blend the mix and you will get kefir that might not taste brand new but will be much better than it was. Whey or milk can also be mixed in to dilute the sour flavor

The main problem with over-fermented kefir is its taste and smell. If you want to lessen the sour flavor, blend it with other less sour or even sweet dairy products. This will make the flavor more tolerable and even enjoyable.

HOT TIP: Try out different blends to get the best results and find what you like best!

Milk kefir fermenting in various sizes of milk bottles, topped with cloth and tied with twine.
Starting kefir from scratch is an option to fix it

#2: Start from Scratch

When kefir gets over-fermented, it curdles and separates. The liquid whey will separate from thicker kefir. The good thing about this stage is that the kefir hasn’t gone bad yet and it is still usable.

You can visibly identify the mass of curds when they start separating from the whey portion of the kefir. Pour the entire batch into a bowl and fish out the grains with a slotted spoon like this one from Amazon, or use clean hands. The best way to do it is to strain them. If done properly, the kefir grains can be reused in the next batch.

#3: Over-Fermented Kefir for Baking

Kefir can be a baking ingredient that substitutes milk or buttermilk and brings variety to your baked goods. It adds both taste and texture to any baked goods. Although over-fermented kefir is quite sour, it still works great in baking.

You can use your overly sour kefir in baking recipes such as:

  • pancakes
  • muffins
  • biscuits

It will work as a great souring agent. You may want to mix in other dairy products if it’s too sour.

#4: Smoothies with Over-Fermented Kefir

You can use over-fermented kefir to make smoothies. They are just tasty and refreshing, plus are packed with all sorts of nutrients and probiotic benefits.

NOTE: Kefir has great probiotic benefits and it blends nicely with drinks.

Use a good mixture of frozen and fresh fruits, and if needed, use other dairy products to balance out the strong flavor of the kefir. All you have to do is blend the mixture until it’s smooth!

#5: Make Sour Ice Cream

There are a lot of sour flavor ice creams, put your over-fermented kefir to good use and make homemade ice cream. It will give any ice cream a sour undertone.

Kefir is a good alternative for sour cream in ice cream recipes. Use over-fermented kefir as the base of homemade ice cream. It’s a very good way to use extra kefir or in this case, over-fermented kefir. Sour kefir ice cream is delicious with:

  • vanilla
  • cocoa powder
  • strawberries
  • dark chocolate

#6: Sour Kefir Cheese

Making kefir cheese is a good way to use up extra kefir or over-fermented kefir. To make cheese with over-fermented kefir, strain and separate the kefir first.

To strain, pour the milk kefir into one of these types of cloth, (I’ve linked to the product on Amazon where available):

Drain off the whey, wrap the cheese in a storage cloth like this one, and place it in a colander. You can mix salt and other flavors into it at this stage. Kefir cheese is a little strong-flavored, so keep that in mind when pairing it with food.

#7: Kefir Salad Dressings

You can use kefir in any kind of salad dressing that calls for a sour kick. Mix other strongly flavored ingredients to mask the kefir taste if you don’t like the flavor. Make it with fresh ingredients and the kefir will add gut-friendly probiotics for a healthy dressing.

To make salad dressing, use over-fermented kefir to replace:

  • yogurt
  • sour cream
  • buttermilk

Use adequate amounts to your liking of:

  • lemon juice
  • salt
  • pepper
  • garlic
  • spices
  • herbs

Boom! Just like that, now you have a tasty salad dressing or dip for your favorite vegetables!

A metal bowl filled with ice keeping 2 homemade popsicles with berries cold, on a light and blue background with fresh mint surrounding.
Homemade popsicles are a great way to use over-fermented kefir

#8: Make Healthy Kefir Popsicles

Kefir is good for digestion and is a great addition to homemade popsicles, making them a healthy dessert alternative. This recipe is great for over-fermented kefir too.

Making healthy kefir popsicles is easy. First, blend these ingredients until smooth:

  • kefir
  • frozen fruit
  • honey

Pour the blend into popsicle molds, and freeze. It’s as simple as that! Try different amounts of kefir and honey to find a taste and balance best for you.

#9: Over-Fermented Kefir Parfait

Everyone loves a parfait. They are so tasty as well as:

  • smooth
  • creamy
  • fluffy

Use over-fermented kefir to make the creamy layer of a parfait with a combination of:

  • yogurt
  • sour cream
  • kefir

Complement the creamy layer with fresh delicious fruits.

  1. Add berries and bananas for sweetness with lower sugar content.
  2. Add a little fruit chutney to boost the flavors.

You can make different kinds of kefir parfaits, such as:

  • vanilla
  • strawberry
  • chocolate

#10: Use Kefir for Skin Care 

It may sound weird at first, but the good bacteria in kefir can actually help to heal your skin, and get rid of dead skin.

There are many different ways to make a face mask using over-fermented kefir. Try these ingredients:

  • cucumber juice
  • egg white
  • egg yolk
  • raw kefir

Simply apply it to your skin and rinse it off after 15-20 minutes.

#11: Use Over-Fermented Kefir in Everyday Dishes

Kefir isn’t only good for baking and desserts, it can be added to dishes you eat daily. Use it in mashed potatoes or your favorite soup, or try out the sour flavor of over-fermented kefir in a barbecue chicken dish.

Other ways to use over-fermented kefir in everyday cooking:

  • as a marinade
  • to tenderize and flavor meat
  • dip chicken in it to make fried chicken

Why Does Kefir Get Over-Fermented?

If the process of fermentation goes on for too long and there is too much culture then it is called over-fermentation. Most cultures have a recommended environment and time for fermentation. If they are not followed properly, the culture may get over-fermented.

Jars of milk kefir and a bowl in the background with milk kefir grains strained out.
There are several main things that cause kefir over-fermentation

Here are some of the main reasons why kefir gets over-fermented or separated:

  • Left to ferment too long: The recommended time to ferment milk kefir is a little more than 24 hours and 48 hours for water kefir. If left for longer, the kefir will start to separate. Place them in the fridge if you’ll be away for any length of time.
  • High temperature: Kefir cultures very quickly at a warmer temperatures. Anything above 77 degrees Fahrenheit is considered too warm. Depending on the temperature, milk kefir can start to separate as early as 12 hours. So, be sure to keep an eye on it.
  • Too many grains: Given the right condition, kefir grows very quickly. Kefir grains are extremely active and strong. They multiply quickly and before you know it, the grains will need more milk. You may think that your kefir is not done because it’s thin, but it’s the opposite. If you do not add enough milk, they will ferment the milk faster.
  • Don’t ferment too much at once: Only culture enough so that you can use it at the right time. Leave the rest in the fridge, or share them with your friends.

How to Tell If My Kefir Is Over-Fermented?

If it’s your first time fermenting kefir, you might be very concerned about the process and how to tell it’s overdone. It’s easy to tell if kefir is over-fermented, these are the main signs to look out for:

  • the whey is separated from the milk
  • a brownish liquid piled up on the bottom of the jar
  • the rest of the mix floating on top

One of the biggest changes in over-fermented kefir is the taste. The kefir will taste very sour if the brew has fully separated. Sometimes giving it a good stir to mix it back again can it from over-fermenting. Then, move the kefir to a colder place like the refrigerator to slow the fermentation down.

Water kefir doesn’t change much in appearance during fermentation. When water kefir is finished, it still tastes sweet but will become sour as it over-ferments. If left for a very long time it may become too sour to drink.

The smell of kefir also changes depending on the stage of fermentation. When over-fermented, it may smell like vinegar. Some people claim that over-fermented kefir smells like vomit.

Is Over-Fermentation Bad for Kefir?

As long as you haven’t been fermenting your kefir for too many days, it should still be okay. Over-fermented kefir doesn’t mean it’s rotten. As you’ve already read in this article, there are many uses for over-fermented kefir. Some may even like the taste of kefir fermented a little longer than usual.

If your kefir has started separating, you don’t need to throw it out in the trash yet. It’s still usable and the probiotic effects of the kefir are still there. Most of the time, you can:

  • give it a good whisk
  • add some more milk or water
  • then drink it normally

If kefir is over-fermented, it’s probably better to not serve it to guests. Not everyone likes the sour taste or smell of over-fermented kefir.

Although over-fermentation is not bad in the case of kefir, it can be problematic for other products. For example, over-fermented dough will:

  • taste too sour
  • lose its structure
  • be hard to bake with

How to Prevent Over-Fermentation?

As I’ve said earlier, there are some key reasons for over-fermentation. So, if you keep a close watch on these factors, you can prevent it from happening. Here are some tips to help you prevent over-fermenting your kefir:

#1: Pay Attention to The Temperature

The hotter the environment is, the faster the kefir ferments. Ensuring the right temperature is the most important part of fermentation. If the environment is warm enough, around 72 degrees Fahrenheit, the kefir will develop properly.  If it’s too cold, your kefir will stall and not ferment at the right time. Also, if the environment is too hot, the kefir will ferment too quickly and start separating.

Room temperature is fine depending on where you live. In hotter areas, you might need to place the kefir in a place with cooler air. Similarly, if your area is too cold, you should select a warmer spot to keep your fermented kefir.

Kefir grains in a strainer over a jar, with a spoonful of grains being taken out.
It may help to reduce the number of kefir grains in the ferment

#2: Reduce the Number of Grains Used

Using too much grain is one of the reasons for over-fermentation. Try reducing the number of grains to see if it changes the result. If you’re using too much grain but not enough milk, your kefir will ferment really fast. Kefir grains multiply very quickly, and the liquid may look thin at first sight, but it’s actually the other way around.

If too many grains have been added, you can add some milk to balance it. If the grains have increased and you have not added enough milk, they will ferment faster and you might not notice the kefir is ready and thick, leading to over-fermentation. So, make sure to use the proper amount of milk with the right amount of kefir grains.

#3: Observe How the Kefir Develops

Check the brew every once in a while, to monitor how it develops. Make sure it isn’t separating, and take a little taste to see how it is. It is often best to start fermentation at night before bed and check on them first thing in the morning.

#4: Keep Track of the Time

Make sure to keep track of the time when you’re fermenting kefir. If you have the proper environment, milk kefir will ferment in 24 hours and water kefir in 48 hours. If you are going away on vacation, I recommend keeping your kefir brew in the fridge.

But remember, the fermentation speed depends a lot on temperature. So, if you don’t have proper control over the temperature, pay closer attention to the condition of the brew. Even a temperature rise of 3-5 degrees can cause the kefir to ferment much faster.

Fermenting food properly is not easy. To do it smoothly, you need:

  • patience
  • dedication
  • to keep track of various factors

Follow all of the tips mentioned here and you’ll be a fermentation master in no time.

A strainer with kefir grains, and small jars with kefir topped with fruit and nuts, top view.
You’ll be a kefir master in no time!


Fermented kefir is a versatile and probiotic food that can be used in a lot of different recipes and makes them healthier. If you’re not experienced at fermenting, you may over-ferment your kefir mix. However, as seen in this article, over-fermented kefir can still be used in many different ways.

Kefir is very nutritious and rich in probiotics. Over-fermenting doesn’t make it lose its nutritional value. So, it’s safe to use over-fermented kefir in any kind of recipe. With proper care and practice, you can master the trick of fermenting kefir very fast. It’s not that complicated once you get the hang of it!

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