What Is Buttermilk (+ DIY Substitute)
Not just sour milk — buttermilk's acidity creates tender, flavorful baked goods.
What Is Buttermilk?
Buttermilk is a fermented dairy product — milk cultured with lactic acid bacteria. Despite the name, it contains little to no butter. The fermentation gives it a tangy flavor and thick, creamy consistency.
Why Bakers Love It
Buttermilk's acidity does three things: 1. Tenderizes — acid breaks down gluten, creating a softer crumb 2. Leavens — reacts with baking soda to create CO₂ for rise 3. Adds flavor — the tang balances sweetness in cakes and breads
US vs UK
- US: Buttermilk is widely available in supermarkets
- UK/EU: Less common in stores, but easy to make (see below)
DIY Buttermilk Substitute
The easiest swap that works in every recipe:
For 1 cup (240ml) buttermilk: - Add 1 tablespoon white vinegar or lemon juice to a measuring cup - Fill to 1 cup line with regular milk - Stir and let sit 5-10 minutes until it curdles slightly
This works because you're replicating what makes buttermilk special — the acidity.
When to Use Buttermilk
- Chocolate cake (reacts with baking soda + cocoa)
- Banana bread
- Pancakes and waffles
- Fried chicken (tenderizes the meat)
- Scones