Sour milk is a fermented, probiotic-rich cultured dairy food you can easily make with raw milk. A terrific technique to use up older and surplus raw milk, sour milk has many uses in recipes and beyond. And if you don't have raw milk, I will show you how to make sour milk from pasteurized milk too.
Traditionally made sour milk done in the old way from raw (unpasteurized) whole milk that has been left out somewhere warm to naturally turn is a healthful dairy product that has an incredible array of uses. It is also a powerful natural probiotic.
Using soured milk is an old way to leaven bread without the use of yeast, but you can also drink it straight for its pleasantly sour taste.
I have a recipe for traditional Irish soda bread that uses buttermilk (which can be replaced with soured milk).
You can also ferment the sour milk further until it thickens and separates into curds and whey and eat it as you would yogurt. If you have older raw milk kicking around — do not let it go to waste. Make sour milk instead.
You absolutely must use raw (unpasteurized) milk to make real and safe sour or "clabbered" milk.
Pasteurized milk will not contain the good bacteria that flourish at room temperature.
For pasteurized milk, we add an acid (lemon juice or apple cider vinegar) and let it sit for a few minutes.
Let's talk about the differences between some confusingly similar things: sour milk, spoiled milk, buttermilk, clabbered milk, and whey.
What is the difference between soured milk and spoiled milk?
Soured milk is raw milk that has been left out at room (or warmer) temperatures for a period of time until it becomes slightly thicker and takes on a sour taste.
The timeframe is usually around 24 hours for this process to occur.
Spoiled milk is milk that has gone bad and is not fit for consumption.
Spoiled milk can be quite dangerous as it's teeming with all sorts of bacteria, many of which are hostile to the human digestive tract. Milk that has spoiled will not have the pleasantly sour, fermented taste of soured or clabbered milk but will taste and smell absolutely disgusting.
Your nose will tell you that the milk is bad.
Please note that dangerous pathogens can flourish and multiply in any milk whether it smells or tastes "off" or not. This is true for unpasteurized and pasteurized milk alike.
Then there is also buttermilk which is the liquid leftover from the butter-making process. It can be made from sweet cream or cream that has been left to culture (i.e ferment) at room temperature for about 24 hours.
I describe this process in great detail here where I teach you how to make cultured butter or sweet cream butter.
Buttermilk is sometimes called whey as well.
Sweet & Acid Whey
And of course, there is also whey which is the liquid leftover from the cheesemaking process.
There are even two types of whey, the first is acid whey which results from making vegetarian cheese like in my paneer recipe.
The second is sweet whey which is leftover from renneted cheeses. Rennet is the enzyme found in a calf's stomach.
Whey is a protein-rich drink.
Clabbered Milk or "Bonny Clabber"
Clabbered milk or bonny clabber (Bainne Clábair) is a type of soured milk. Bonny clabber is, again, raw whole milk left out at room or warmer temperatures until it sours and then thickens up even more than simple soured milk. Clabbered Milk is the same as Curds & Whey as it will separate into thick sour curds leaving the whey at the bottom.
Clabbered milk can be considered a type of yogurt.
In my experience, this process to make clabbered milk can take as long as 72 hours but it depends on your kitchen and climate.
Soured milk does not ferment long enough for this separation to occur and that is its key difference from clabbered milk.
Sour Milk Substitute
This will work in a pinch but it is not even remotely close to true sour milk.
However, if you need some RIGHT NOW for a baking project — add 1 teaspoon of plain vinegar or lemon juice per 1 cup of milk and after letting that sit for 5-10 minutes you will have a facsimile that would work decently enough when needed.
You can use pasteurized or raw milk for this technique.
Recipes Using Sour Milk
- My historic recipe for Irish Soda Bread Using Einkorn Wheat depends on sour milk (or buttermilk) to leaven the bread.
- You can also use sour milk instead of kefir in my nutrient-dense Raw Kefir Smoothie.
(And if you're looking for more nourishing real milk recipes, my hot spiced milk is phenomenol.)
10 More Practical Uses For Sour Milk
There are many uses for soured milk. Here are just a few.
- Drink it on its own. Why buy expensive probiotic supplements if you have access to nourishing sour milk? It's teeming with beneficial gut bacteria.
- Use it to make your fermented chicken feed more nutritious.
- Or just feed it directly to your livestock.
- Remove the bitterness from liver. Soak your liver in soured milk for 4-8 hours, or even overnight. This will remove any bitterness and may win over liver haters.
- Tenderize meat. Soured milk will tenderize any tough cut of meat you have.
- Bake/cook anything. Any recipe calling for buttermilk can generally also be substituted with soured milk. You can even sub regular milk with sour often enough. There are a ton of recipes out there for fried buttermilk chicken, cookies, pancakes, scones, cake etc.
- Soak grains. Properly prepare your grains by soaking them in soured milk. This process will render many of the toxic anti-nutrients naturally found in grains inert or at least greatly diminish the effect.
- Gardening. Dilute the soured milk with plain water and use it as a nourishing source of calcium and other things in your vegetable gardens.
- Skincare. Lactic acid is a common and powerful ingredient used in skincare. It exfoliates the top layers of your skin leaving it refreshed and glowing. Try this once a week to start. Just rub some soured milk on your face and wash it off after about 20 minutes before applying your moisturizer.
- Leave it out longer until it separates into curds and whey — make clabbered milk or bonny clabber. This can take up to 72 hours but will depend entirely on the conditions (temperature and humidity) of your kitchen. Enjoy plain or spiced with cinnamon, nutmeg, maple syrup, raw honey etc.
- 1 quart whole milk
- 1 teaspoon lemon juice (or apple cider vinegar)
RAW Milk Instructions
- Leave your raw, whole milk (covered) at room temperature for 24 hours or until it has become soured and slightly thickened but not separated.
- To make clabbered milk, leave the milk out longer (up to 72 hours or more) until it naturally separates into curds and whey.
- Spoon out the curds and eat them plain or flavoured with spices and fruits.
- Use the leftover whey in smoothies.
PASTEURIZED Milk Instructions
- For every cup of milk, add a teaspoon of lemon juice or apple cider vinegar.
- Let stand at room temperature for 5-15 minutes.