What It Means If Your Buttermilk Has Separated

Buttermilk sees a lot of use in the kitchen, poured into recipes for scones, cakes, biscuits, spicy fried chicken – you name it. A glug of the tangy dairy can give whatever baked good or recipe you add it to an incredibly better texture. But, if you've ever opened a carton of buttermilk that's been in the fridge for a while, you might find it separated into a mixture that's half liquid and half chunky solids. Most people's instinct would be to throw it away. But wait, odds are that the buttermilk is still good to use!

You see, the buttermilk we use today is usually produced by adding lactic acid bacteria into milk. Once added, these cultures immediately start their job of converting lactose into sour-tasting lactic acid, which is where buttermilk gets its signature tang. Over time, the buttermilk will become more acidic from ongoing fermentation or overculturing. That's exactly why, eventually, all buttermilk is going to separate.

When acidity reaches a certain point, a common protein in milk (called casein) unravels and separates from the liquid whey, forming into solid, curdled clumps. Once again, this doesn't mean that your buttermilk has expired — unless it has turned moldy or smells unusually sour.

Ever seen the phrase "shake before use" on a milk carton? That's there just in case the milk has settled or separated during storage. When you shake it, the components will combine back into a uniform liquid. The same thing applies here for buttermilk. Simply pour the separated buttermilk into a bowl, and whisk vigorously until everything recombines into a smooth liquid.

Now, this only applies to buttermilk that's slightly separated. If you find the solids have totally separated and the remaining liquid looks very thin and watery, then the buttermilk has likely spoiled. Just to be sure to give it a full sensorial checkup, too. Take a whiff — buttermilk should smell faintly like vinegar, but not overwhelmingly so. You can even give it a taste. Good buttermilk should taste like yogurt, but if you recoil from the sourness, then trust your taste buds and toss it.

While you can salvage separated buttermilk, remember that opened buttermilk will only last in the fridge for so long. You should try and make a habit of using it up within a week or two  – after all, there are dozens of ways to use leftover buttermilk. Not only will you be able to save yourself from the tedious debate of whether or not to use it, but fresh buttermilk is guaranteed to taste and work better in recipes, too!