This is how to make sour milk easily at home. Sour milk is frequently used in baking recipes and makes for a great buttermilk substitute too. You can quickly sour milk yourself at home with any milk you have. Raw milk can also be soured in a traditional longer process which transforms it into a fermented, probiotic-rich cultured dairy food.
How to make sour milk at home in a pinch when a recipe requires it is quite easy. You can also use this soured milk as a substitute for buttermilk.
Sour milk or buttermilk is frequently used in recipes as a way to add or balance acidity and to help some foods rise.
To make 1 cup of sour milk (250 ml( add one 1 tablespoon (15 ml) of vinegar or lemon juice to a measuring cup and then enough milk to equal 1 cup (250 mL). Stir and let stand for 5 minutes before using.
You can use pasteurized store bought milk or raw milk for this technique.
Regarding lemon juice or vinegar, you can use white vinegar or apple cider vinegar. The milk with the vinegar is an age old trick used in a pinch when baking and it works.
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 (like when making traditional Irish soda bread) without the use of yeast. The milk reacts with added baking soda to make bread and baked goods rise. But you can also drink it straight for its pleasantly sour taste or turn it into a fermented milk smoothie.
You can also ferment the sour milk further until it thickens and separates into curds and whey and eat it as you would yogurt.
You absolutely must use raw (unpasteurized) milk to make real and safe sour or "clabbered" milk.
Pasteurized milk that has soured is spoiled milk and not considered safe to drink or use in baking.
Pasteurized milk will not contain the good bacteria that flourish at room temperature.
Let's talk about the differences between some confusingly similar things: sour milk, spoiled milk, buttermilk, clabbered milk, and whey.
Spoiled Milk
What is the difference between sour milk and spoiled milk?
Sour 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 but it can be quicker in a warm environment or spot in the kitchen.
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.
Buttermilk
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"
How to make clabbered milk or bonny clabber (Bainne Clábair) is similar to how you make sour 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.
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.
- Try soured milk in these sourdough discard pumpkin pancakes.
(And if you're looking for more nourishing real milk recipes, my hot spiced custard milk is how I start and end each day.)
📖 Recipe
Ingredients
- 1 cup milk
- 1 tablespoon lemon juice (or apple cider vinegar)
Instructions
RAW Milk (Long Way) Instructions
- Leave any quantity of your raw, whole milk (covered) at room temperature for 12-24 hours or until it has become soured and slightly thickened but not separated.
PASTEURIZED Milk (Instant Way) Instructions
- For every cup of milk, add a tablespoon of lemon juice or apple cider vinegar into a cup measurement. Fill the rest of the way with your milk to equal 1 cup in total.
- Let stand at room temperature for 5-10 minutes.
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Oom Andre says
I am adding 36 or 40 strain probiotics to the process in the hope that these strains will multiply in the product. I will not know if it is successful unless I have it laboratory tested.
Jana Dziak says
That's really interesting. Will you actually be getting it tested? I'd be so curious about the results if you will share them.
Katherine Tokpah says
Thank you so much for the knowledge gained, it will help me a lot to have something doing for my family.
Jana Dziak says
Thank you Katherine ❤️
Scott says
No. The way to make biologically sour milk, is let raw milk ferment. I do, it's great. Works great for my body.
Jana Dziak says
We make and drink raw fermented sour milk regularly too, it’s fantastic!
But to make a poor facsimile of true sour milk when you’re in a pinch and need it for baking — the shortcut works. This is why I discuss both methods and include a recipe for each method.
Lindsay says
So to ferment the raw milk and gave it be safe, is it okay that the fresh raw milk goes into a fridge for 7 days and then when I realize we aren’t getting it used to then set it out on the counter for 24-72 hours???
The Peasant's Daughter says
I do this all the time, but I wouldn’t go past 7 days, and the fresher the better. Depending on the temperature of your kitchen it may affect results too.
Try it out and see what happens. As always, have a trustworthy supply of raw milk.
Alicia says
This is a great article. Thank you so much!! I am wondering, do you put your whey back in the refrigerator or can you just leave it out and use as needed? 🙂
The Peasant's Daughter says
I put it back in the refrigerator but you can also use it to soak grains or flour on the counter. I use leftover buttermilk to soak my Einkorn wheat before making breads like my Irish Soda Bread and I imagine whey would work just as well.
Honor says
Hi, thanks for sharing all of this info! I just tried making curds and whey for the first time. I used fresh raw milk and there was a huge cream portion at the top that I did not remove (thinking maybe I should have?)...after 3 days there was only a small separation of the whey and the milk looked like a giant blob of yogurt. It wasn't really curdled, more smooth. I don't know why, but I lightly shook the jar to mix in the cream. Now I have no idea what to do with this??? It smells ok, kind of like yogurt. Do you have any suggestions for how I could use this now? I don't want to wait for the whey to separate a second time--would it even do that?
The Peasant's Daughter says
Hi Honor, the milk is likely fine and this does sometimes happen! I'm going to add a troubleshooting guide to this post because (unfortunately) most of us don't have years of experience making these traditional foods anymore and there are nuances to it. Depending on the season, the temperature, diet, and even the time of milking the fat content of the milk can vary and create an end-product like this. The best thing to do is to skim off the cream or partially skim it off beforehand. When mine turns out like this I just use it in smoothies with honey, mangos, and strawberries and it's still a lovely probiotic drink.
Bronze says
Worked great! Thanks!
This site is really wonderful! Raw milk, einkorn, and more? I'm hooked.
A question: how does the skimming of cream effect the milk? I usually keep our milk in the fridge till the cream separates then skim 85-95% of it. Should I make sour milk (for baking) out of fresh, unskimmed raw milk or is it just as good made from raw milk with the cream skimmed off of it?
The Peasant's Daughter says
I do both! It depends on if I want to make something special with the cream or not. Growing up my grandmother would skim and save the cream for butter and make other things with the milk. Try both and see what you prefer but you really can't go wrong either way.
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