Should Kefir Taste Like Sour Milk?

One of the most beneficial beverages to can drink to improve your digestion and rebalance your gut flora is the fermented milk drink known as kefir. However, the taste might be something you’ll have to get used to first. You might wonder if you doing it right and if kefir should taste like sour milk?

Kefir should naturally have a slightly sour taste. It should taste similar to sour milk after several hours of fermentation. If your kefir taste too sour you may have let it sit for too long or at too high temperatures.

When I first started making kefir I was surprised at how sour the result actually was. At first I wondered if the milk had perhaps gone bad. But a sour milk taste is actually completely normal. Let’s look at some of the reasons why!

Why does kefir taste like sour milk?

The reason our taste sense perceives kefir as sour is because of something called butyric acid. This acid is a fatty acid frequently found in foods with very distinct tastes and smells, e.g. parmesan cheese.

It is produced during the fermentation process when lactose is broken down into lactic acid and live cultures digest the remaining sugars. The existence of this fatty acid in kefir is completely normal and even desirable.

Butyric acid has plenty of health benefits such as anti-inflammatory capabilities and digestive stimuli. Unfortunately, our bodies have been conditioned by our modern diets to value sugar and sweets over sour and bitter tastes.

What should kefir taste like?

Homemade natural kefir should taste slightly sour, similar to sour milk. When it tastes like milk that has just gone bad you know your kefir grains have completed their job: fermenting the milk.

However, there is no objective way that kefir should taste like. Every batch of kefir will taste slightly different depending on the time and room temperature it was exposed to during fermentation.

Generally, the longer the kefir ferments and the higher the temperature, the sourer it will taste. Some people (including me) also mature their finished kefir in a second fermentation to increase the vitamin content and reduce the lactose content. This will produce an even sourer taste.

Does kefir taste good?

The sour taste of kefir is something most people have to get used to. Personally, I think kefir tastes fantastic. I love it plain after my meals or before going to bed. But to be honest, it took some time to get used to the taste.

As modern humans we are conditioned to value sweet over sour and bitter when in fact all tastes can be indications of valuable nutrients our bodies may crave. The clue to finding your ideal kefir taste is to experiment with fermentation time and temperature until you find your sweet spot.

Mine is 24 hours at room temperature plus a second fermentation of 12 to 14 hours without the kefir grains.

How sour is kefir meant to be?

The sourness of kefir can vary from mild to extremely sour. Everything in this range is possible and usually also safe to drink. Even very sour, eye-pinching kefir, has usually not gone bad.

The wonderful live cultures that have been added to the drink during fermentation prevent the formation of any harmful bacteria and mold. Originally, kefir was invented as a way to preserve milk when fridges had not yet been invented.

How to make kefir taste less sour

But, if you find even mild kefir still too sour to consume or just want to try something different there are a lot of ways to make your kefir taste less sour. We can either tweak the fermentation process or we can add ingredients after the fermentation is finished. I’ll cover both methods right here!

The fermentation process

The easiest way to make kefir taste even better is to modify the fermentation process and make sure we are using high-quality ingredients.

  • Raw Organic Whole Milk: One of the best base products to use to make kefir is raw organic whole milk. Not only does it taste significantly better on its own but it also gives the kefir grains many more nutrients to digest and work with. It is generally recommended to boil or heat the raw milk before fermentation to kill any bad bacteria.
  • Healthy Kefir Grains: To produce the best quality kefir with the most natural flavor you’ll want to make sure that your kefir grains are healthy. Dark or black spots on the grains or a strange lumpy texture can be signs that the microorganisms are no longer suitable to use. Making kefir is a daily process and keeping your grains in the same milk or no milk for too long may make them unusable.
  • Time & Temperature: Modifying the time and temperature in your fermentation process is a simple way to make kefir taste more to your liking. As pointed out above a longer fermentation time usually correlates with a sourer taste. So, if you prefer your kefir less sour let it sit for only 12 hours at first and see if you like the taste.
  • Fermentation Hygiene: Bad fermentation hygiene and dirty jars or lids can negatively affect your kefir’s taste. Since used kefir jars can be a bit of a pain to clean it’s easier to just reuse them. However, this may compromise the taste. (It’s worth to point that some people actually recommend never cleaning your fermentation vessels. But do so at your own peril!)

What you can add

We can also add many different ingredients to make kefir taste less sour. Fruits are of course the first thing that comes to mind but there are many more options:

kefir smoothie
Kefir Smoothie
  • Add Fruits: Strawberries, blueberries, bananas are all great options to add to your kefir drink to make it taste less sour and sweeter. My personal favorite is kefir with strawberries. The incredible sweetness of the berries just blends perfectly with the tangy sourness of kefir. Try it out 😉
  • Add Honey: If you’re looking for natural ingredients that will make your kefir less sour look no further than honey. And if you are adding local honey you’ll get the added benefit of consuming local pollen to help boost your immune system and alleviate allergies.
  • Mix It To A Smoothie: Another way to make your kefir taste less sour is to blend everything into a smoothie. Simply replace the amount of milk you would typically use with kefir and you’ve got a healthy and nutrient-dense kefir milkshake. Feel free to add some nuts or seeds to make the smoothie even more nutritious.
  • Replace Your Milk In Cereal: Why not replace the milk in your cereal with kefir? Although the taste will be a little sourer you’ll have added so many probiotic benefits to your morning snack. Be careful not to use a metal spoon when eating your cereal though since this can destroy the live cultures in kefir. A plastic or wooden spoon will do just fine.


It is completely normal that kefir tastes kind of like sour milk. Don’t worry! In fact, the sour taste is an indication that your kefir has fermented correctly and is now packed with beneficial bacteria.

You can also tweak the fermentation process or add some fruits and other sweeteners to your kefir if your taste buds have not yet quite become accustomed to the taste.

So, next time you taste that delicious sourness just think of all the live cultures and vitamins that you are ingesting!


  • Hi, I'm Marvin! In early 2019 I started fermenting sauerkraut, kefir, and kombucha and noticed the incredible health benefits that came with it. I was less irritated, had fewer allergies and my skin got better. I started this blog to share how fermented foods have helped me and how simple they are to prepare! Look around and see what speaks to you and all the best on your fermentation journey!

1 thought on “Should Kefir Taste Like Sour Milk?”

  1. Thanks for posting this information! I’m new to raw kefir and I wasn’t sure if it had turned because maybe it goes bad sooner than pasteurized kefir? I didn’t want to throw it out if that was how it’s supposed to taste! I’m not brave enough yet to make my own, so I pay about $7-8 for a quart. I believe the probiotics that occur naturally will be the most beneficial for my allergies and haven’t felt success w bottled versions. I will continue to learn more from ur website!


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