To make buttermilk at home, stir 1 tablespoon of lemon juice or white vinegar into 1 cup (250 ml) of milk. Leave it on the bench for 5 to 10 minutes, until it thickens slightly and small curds form. Full cream milk gives the closest result to real buttermilk. For a dairy-free version, unsweetened soy milk works best.
What's the best milk for buttermilk?
Full cream milk. It gives the thickest, most buttermilk-like texture. Reduced-fat milk works too, but it comes out a little thinner. Skim milk is fine for baking, but it doesn't curdle as visibly.
| Milk for buttermilk | How well it works | Milk | Acid |
|---|---|---|---|
| Full cream milk | Best. Thickest texture | 1 cup (250 ml) | 1 tbsp lemon juice or white vinegar |
| Reduced-fat (light) milk | Good. A bit thinner | 1 cup (250 ml) | 1 tbsp lemon juice or white vinegar |
| Skim milk | Fine for baking. Thin and curdles less | 1 cup (250 ml) | 1 tbsp lemon juice or white vinegar |
| Unsweetened soy milk | Best dairy-free option. Thickens well | 1 cup (250 ml) | 1 tbsp lemon juice or vinegar |
| Oat or almond milk | Works, but stays thin. Almond barely curdles | 1 cup (250 ml) | 1 tbsp lemon juice or vinegar |
You don't need to be exact with the acid. Recipes range from 3 teaspoons per cup to 2 tablespoons per cup. More acid gives a thicker, tangier result.
How do you make buttermilk with milk and lemon juice?
You're adding acid to milk. The acid lowers the milk's pH, so it thickens slightly and turns tangy, much like the buttermilk you buy.
- Put 1 tablespoon of lemon juice or white vinegar in a measuring jug.
- Top it up with milk to the 1 cup (250 ml) line.
- Stir, then leave it for 5 to 10 minutes.
- Stir again and use it in place of the buttermilk in your recipe, cup for cup.
Lumps are normal. They mean the acid has worked. And if you don't see many curds, it will still do the job in your batter. You won't notice the curds in the finished bake.
Australian vs US measurements
An Australian tablespoon holds 20 ml. American and British recipes use a 15 ml tablespoon, and an American cup is 240 ml instead of 250 ml. For homemade buttermilk the difference doesn't matter, since either spoon works. Just use the same cup for the whole recipe.
What's the difference between milk and buttermilk?
The main difference is acidity. Buttermilk is acidic, so it reacts with bicarb soda and helps a batter rise. Plain milk isn't acidic enough to do that. If you use plain milk in a recipe written for buttermilk and bicarb, it can bake up flat and dense.
| Milk (full cream) | Buttermilk | |
|---|---|---|
| What it is | Pasteurised cow's milk | Milk cultured with lactic acid bacteria (traditional buttermilk is the liquid left after churning butter) |
| Taste | Mild, slightly sweet | Tangy, sour |
| Texture | Thin | Slightly thick |
| Reacts with bicarb soda? | No | Yes, which gives lift to scones, pancakes and cakes |
| Energy per 100 ml | About 255 kJ (61 Cal) | About 259 kJ (62 Cal) for whole, or about 180 kJ (43 Cal) for low-fat |
| Fat per 100 ml | 3.2 g | 3.3 g whole, 1.1 g low-fat |
| Protein per 100 ml | 3.3 g | 3.2 g whole, 3.5 g low-fat |
| Best for | Drinking, sauces, everyday cooking | Scones, pancakes, cakes, fried chicken batter, dressings |
Nutrition figures come from US data for whole milk and cultured buttermilk. Kilojoules are converted from Calories (1 Cal = 4.184 kJ). Australian brands vary, so check the label.
Lemon juice or vinegar: which acid is best?
Both work. White vinegar has the most neutral flavour, and lemon juice adds a light citrus note. Once the batter is baked, it's hard to tell which one you used.
| Acid | Per cup (250 ml) of milk | Flavour | Good for |
|---|---|---|---|
| Lemon juice | 1 tablespoon | Bright, a little citrusy | Cakes, pancakes, berry muffins |
| White vinegar | 1 tablespoon | Clean, neutral | Savoury bakes, fried chicken batter |
| Apple cider vinegar | 1 tablespoon | Slightly fruity | Pancakes, spiced bakes |
| Cream of tartar | 1¾ teaspoons | Very mild | Scones, biscuits |
Cream of tartar clumps if you add it straight to a full cup of milk. Mix it with about 2 tablespoons of the milk first, then stir in the rest. Check the use-by date too, because old cream of tartar may not work.
How do you make dairy-free buttermilk?
Use unsweetened soy milk with the same ratio: 1 tablespoon of lemon juice or vinegar, topped up to 1 cup with soy milk and left for 5 to 10 minutes. Soy milk thickens best because it has more protein than most plant milks.
Oat milk works but can taste a little sweet. Almond milk barely curdles and stays thin. It still adds acid to the batter, just not the thick texture.
No lemon or vinegar? Other buttermilk substitutes
If you have no acid at all, a cultured dairy product can stand in:
- Plain yoghurt and milk: mix equal parts. For a thicker result, use ¾ cup yoghurt to ¼ cup milk.
- Sour cream and water: mix equal parts.
- Kefir: use plain, unsweetened kefir cup for cup.
Getting the dry ingredients ready too? Plain flour has no raising agent, which is why so many buttermilk recipes add bicarb soda. This guide to all-purpose (plain) flour in Australia explains how it differs from self-raising. And once you've got the hang of it, try something heartier, like this cheese and bacon cob loaf for your next get-together.
FAQ
Can you use UHT milk to make buttermilk?
It may not curdle as well as fresh milk. If it won't thicken, try lemon juice instead of vinegar. The acid will still react with bicarb soda in your batter, even without visible curds.
Does the milk need to be at room temperature?
No. Milk straight from the fridge works. Room-temperature milk may curdle a little faster.
Can you use homemade buttermilk in scones?
Yes. When you make buttermilk at home for scones, swap it cup for cup for the buttermilk in the recipe. It gives the same tang and helps the bicarb soda work.
Can you drink homemade buttermilk?
It's safe to drink, but it tastes sharp and isn't very pleasant on its own. It's meant for cooking and baking.
How long does homemade buttermilk last?
It's best used straight away. Sources disagree on how long it keeps, with suggestions ranging from a day to about 5 days in the fridge. To be safe, cover it, refrigerate it and use it within a day or so.
Making buttermilk at home takes two ingredients and ten minutes. Pick full cream milk for the best texture, or soy milk if you need it dairy-free, then add a tablespoon of lemon juice or vinegar per cup.
Next time a recipe calls for buttermilk, mix a cup before you start measuring the dry ingredients. It'll be ready by the time you need it.
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