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Clabber Milk – What It Is, Why You Should Eat It, and How To Make It

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What is clabber milk?

Clabber milk is a naturally fermented milk product that can be eaten raw or used in recipes. It also has a little leavening power all on its own, so it’s great to add to baked goods.

A glass jar of clabber milk with text overlay.

Raw cow’s milk is full of naturally occurring beneficial lactic acid bacteria. When that bacteria is supported with a warm environment, it will ferment the milk and create something like a cross between yogurt and kefir. Eventually, if left to ferment long enough, the clabber milk will separate into curds and whey.

Fermenting or souring milk is VERY different than having milk spoil. Spoiled milk only occurs if the beneficial bacteria found in clean raw cow’s milk have been killed by pasteurization, thus allowing mold spores or other contaminants to flourish.

In a fermented milk product, the lactic acid bacteria have soured the milk with the lactic acids they produce while consuming lactose. The higher acidity keeps other microbes that can be harmful to humans from growing. It is very important that you use only high-quality raw milk from clean grass-fed cows when making clabber milk.

A bowl of clabber milk with honey and crackers.

Clabber milk with honey

Why Should I Eat Clabber Milk?

In Harold McGee’s book “On Food and Cooking, The Science and Lore of the Kitchen” he elaborates on “The Health Benefits of Fermented Milks,” stating:

The standard industrial yogurt and buttermilk bacteria are specialized to grow well in milk and can’t survive inside the human body. But other bacteria found in traditional, spontaneously fermented milk-Lactobacillus fermentum, L. casei, and L. brevis, for example-as well as L. planetarium from pickled vegetables, and the intestinal native L. acidophilus, do take up residence in us. articular strains of these bacteria vPariously adhere to and shield the intestinal wall, secrete antibacterial compounds, boost the body’s immune response to particular disease microbes, dismantle cholesterol and cholesterol-consuming bile acids, and reduce the production of potential carcinogens.

Mr. McGee makes a good case for eating a variety of fermented foods other than commercially produced products.

Making Clabber Milk

The process is very simple.

Start by sterilizing a glass jar and lid in boiling water. To do so, fill your jar with hot tap water to avoid shattering the glass with the heat difference. Add the lid directly to the pan of boiling water, empty the jar of the warm water and pour boiling water into the warmed jar, and let it sit for a few minutes. Empty the jar and air dry the lid and jar on a clean towel. Let the jar and lid cool completely before using.

Add the raw milk to the sterilized jar and secure the lid loosely.

Ferment the raw milk at room temperature until the milk sours and starts to separate. This can take between 1 to 5 days depending on the age of the milk, the temperature in your home, and the natural bacteria in the milk itself.

When the clabber has solidified it can then be skimmed off the clotted cream, used for baking, eaten like yogurt, or strained to separate the curds from the whey.

After straining the clabber, the whey can be used as a starter for any lacto-fermented project from veggies to grains, and is especially useful for starting a new batch of clabber milk. Using a tablespoon of clabber whey in the new batch of milk will speed the fermentation process along considerably. The curds will thicken and sweeten with straining and take on a cream cheese-like texture.


Thursday 17th of November 2022

What can happen if you just leave your regular carton of raw milk out on the counter with the lid on? Mine did clabber, but the taste of it ended up kind of bitter. I'm not sure if that's good or not, if clabber is normally supposed to be salted or something after it's done. Can anyone comment on this?

Butter For All

Monday 28th of November 2022

Hi Amy,

If it's pasteurized milk that you left out, it is not safe to consume. If it's raw milk, it should have a sweet and tangy flavor. It may take several batches, using some of the previous clabber, to achieve a nice balance.

It can be salted if you plan to drain the whey and make a quick cheese. Otherwise it's eaten like yogurt, used to soak seeds, or used in baking.

Hope this is helpful!



Sunday 6th of November 2022

I’ve tried to clabber milk twice now. The first time, I got a spot of mold. And this time, I’m on day 5 and it’s still not separating the way it should (it seemed to be working at first but now there’s some thick yellow spots on top and I still don’t have curds and whey). Any tips on what I could be doing wrong?!

Butter For All

Tuesday 8th of November 2022

Hi Lexi!

For the mold, make sure you sanitize your jars, lids and any equipment you use. How fresh is the milk? Because older raw milk clabbers faster than fresh. If the milk is very fresh it can take longer. You can also always help it along by sticking the jar in a warm water bath for a few hours everyday. I hope this helps!



Friday 28th of October 2022

Question... May I use previously refrigerated raw milk to start a clabber or is it best to use the raw milk immediately after milking that day? Thank you!

Butter For All

Monday 31st of October 2022

Hi Keelia,

Yes you can use refrigerated milk. The older it is, the faster it will clabber. Once it's clabbered you can use a little to inoculate a new batch of fresh milk if you choose.

Hope that helps!



Tuesday 23rd of August 2022

What if your raw milk spoiled in the fridge and started to separate? I just got rid of some about two weeks old.. new to raw milk.. is it no good if it’s separates and spoils in the fridge? How long can you actually keep raw milk before you can’t consume it anymore?

Butter For All

Tuesday 23rd of August 2022

Hi Leah,

Raw milk changes. It doesn't really spoil unless there are undesirable microbes in the milk or container. I often use my older raw milk that doesn't taste super great for drinking in sourdough bread dough and it's wonderful. As for how long you can keep it, I unfortunately can't advise, but let's just say your nose will know!

Just a note about raw milk in general tho. It should last at least two weeks under refrigeration without separating. You might make sure your source is super clean, and that your fridge is set to a very cold temp.

Hope this is helpful!


Sunday 7th of August 2022

I have accidentally left out a jar of milk pasturized (not ultra pasturized) for a day or two and came back to find it began to solidify. Not spoiled and if I tasted it, it just tasted like thick milk. Is it possible that it was clabbered? I live in San Francisco so I am wondering if the temperate climate and famous microbes were doing their thing. When I lived in other places, the milk just went sour.

Butter For All

Thursday 11th of August 2022

Hey Monica!

It is definitely possible it clabbered. Did you have it in a jar used for other cultures or ferments? Because of liability I can't recommend you use it, but it is very interesting!