Buttermilk works in some recipes but not others, and the swap changes how your food turns out
Buttermilk is not a direct swap for regular milk. The two have different acidity levels, fat content, and thickness. Buttermilk will curdle in some dishes, make baked goods rise differently, and add a tangy flavor that doesn't belong in every recipe. Whether you can use it depends on what you're making and whether you're willing to adjust other ingredients.
The core issue: buttermilk is acidic (pH around 4.5), while regular milk is nearly neutral (pH around 6.7). That acidity matters. In baking, it reacts with baking soda to create lift. In custards and cream sauces, it can cause the milk proteins to separate. In coffee or cereal, it will taste noticeably sour.
Key Takeaways
- Buttermilk works well in pancakes, biscuits, and cakes because the acidity activates baking soda and creates a tender crumb.
- Buttermilk will curdle in hot sauces, soups, and custards unless you temper it slowly or reduce the heat.
- If a recipe calls for milk and baking soda together, you can substitute buttermilk and reduce or remove the baking soda.
- Buttermilk adds a sour, tangy flavor that works in savory dishes like fried chicken marinades but tastes wrong in cream soups or coffee.
- If you use buttermilk in a recipe designed for regular milk, you may need to add baking soda to neutralize the extra acid.
When buttermilk is a good substitute
Buttermilk works best in baked goods that already call for baking soda. Pancakes, biscuits, waffles, and quick breads all benefit from the swap. The acid in buttermilk reacts with baking soda to produce carbon dioxide, which creates lift and a tender crumb. If the recipe already lists both milk and baking soda, you can often swap buttermilk for milk one-to-one without changing anything else.
Buttermilk also works in marinades and dressings. The acidity tenderizes meat and adds flavor. Fried chicken, buttermilk ranch dressing, and marinated pork all use buttermilk intentionally. The tangy flavor is part of the dish.
Cakes and muffins that use baking soda (not just baking powder) are also good candidates. The buttermilk will make the crumb more tender and add a subtle tang that often improves chocolate or spice cakes.
When buttermilk will cause problems
Do not use buttermilk in hot sauces, gravies, or custards. The heat and acidity together cause the milk proteins to separate and curdle. Cream sauces, béchamel, and custard-based desserts will break. If you must use buttermilk in a warm dish, add it at the very end, off the heat, and stir it in slowly.
Buttermilk is also wrong for coffee, cereal, or any dish where plain milk flavor is expected. The sour taste will be noticeable and unwelcome. Cream soups, mashed potatoes, and milk-based puddings will taste off.
Recipes that call for milk without baking soda—like quiches, cream pies, or white sauce—should not use buttermilk straight. The extra acid has nowhere to go and will make the dish taste sour.
How to adjust a recipe if you use buttermilk
If the original recipe calls for milk and baking powder only (no baking soda), you can still use buttermilk, but add 1/4 teaspoon of baking soda for every cup of buttermilk. This neutralizes the acid so it doesn't make the batter taste sour. The baking soda will also help the baked good rise.
If the recipe calls for milk and baking soda together, you can swap buttermilk for milk one-to-one. The acid in the buttermilk will do the work the baking soda was meant to do. You may reduce the baking soda slightly, but you don't have to remove it entirely—a little extra won't hurt most recipes.
For savory dishes like soups or sauces, use buttermilk only if you add it at the end, off the heat, and whisk it in slowly. Never let buttermilk boil. If you're making a warm dish and want buttermilk's tang, stir it in just before serving.
What happens if you use buttermilk in the wrong recipe
If you accidentally use buttermilk in a recipe that expects regular milk, the results depend on the dish. Baked goods may rise too much or taste slightly sour. Sauces may curdle and look grainy. Custards and puddings may separate. Coffee will taste noticeably tangy.
In most cases, the dish is still edible but not what was intended. If you catch the mistake before baking or cooking, you can sometimes fix it by adding a pinch of baking soda (which will neutralize the acid) or by diluting the buttermilk with regular milk.
Making buttermilk if you don't have it
If a recipe calls for buttermilk and you don't have it, you can make a substitute. Mix 1 cup of regular milk with 1 tablespoon of lemon juice or white vinegar. Let it sit for 5 to 10 minutes until it curdles slightly. This mimics the acidity of real buttermilk and works in most baking recipes.
This substitute is not identical to real buttermilk (which has a different bacterial culture and slightly different flavor), but it performs the same chemical function in baking. It will not work as well in marinades or dressings where you want the full buttermilk flavor.
Buttermilk versus milk in common recipes
| Recipe Type | Can You Use Buttermilk? | Notes |
|---|---|---|
| Pancakes, waffles, biscuits | Yes, one-to-one | Works great; activates baking soda for lift |
| Cakes and muffins (with baking soda) | Yes, one-to-one | Add 1/4 tsp baking soda per cup if recipe has no baking soda |
| Cream sauces, gravy, béchamel | No, or with caution | Will curdle if heated; add at end, off heat |
| Custards, puddings, cream pies | No | Acid will cause separation; use regular milk |
| Coffee, cereal, drinking | No | Sour taste is unwelcome |
| Marinades, dressings, fried chicken | Yes, intentionally | Tangy flavor is part of the dish |
| Quiches, cream soups | No | Will taste sour; use regular milk |
Frequently Asked Questions
Can I use buttermilk in mac and cheese?
Not as a direct swap. Buttermilk can curdle when heated with cheese. If you want to use it, add it at the very end, off the heat, and stir gently. Better to use regular milk or cream for the sauce and save buttermilk for other dishes.
What if I use buttermilk in a recipe that calls for milk and no baking soda?
The dish will likely taste sour and may have a slightly grainy texture if it's a sauce or custard. If you catch it before cooking, add a pinch of baking soda to neutralize the acid. If it's already cooked, the dish is still edible but not as intended.
Does buttermilk work in scrambled eggs or omelets?
Yes, buttermilk works fine in eggs. It adds a subtle tang and makes the eggs slightly fluffier. Use it one-to-one in place of regular milk. The acid won't cause problems because eggs cook quickly and gently.
Can I dilute buttermilk with water to make it less sour?
You can, but it defeats the purpose. Diluting buttermilk removes the acidity that makes it useful in baking. If you need less sour flavor, use regular milk instead or mix buttermilk with regular milk in equal parts.
Is buttermilk thicker than regular milk?
Slightly, but not enough to matter in most recipes. Traditional buttermilk (the liquid left after churning butter) is thinner than regular milk. Modern cultured buttermilk is about the same thickness. If a recipe is very sensitive to liquid ratio, measure carefully, but in most baking and cooking, the difference is negligible.