What Is Buttermilk? A Thick and Sour Explainer

If you’re anything like me, then you’ve found yourself shirtless in the dairy section, scanning all the butter, yogurt, and milk varieties, trying to decide which one to party with this week. Then you finally spot it, the forbidden milk. The milk you fantasize about, yet never touch: buttermilk. Its very existence has made you question reality; what is buttermilk? Is it butter? Is it milk? What is it used for? What is it made of? What is cultured buttermilk and does that mean that buttermilk has gone to college? Let’s get into all of those questions. 

What is buttermilk? 

Buttermilk is fermented milk. There are two ways to get there: the old way and the new way. For old school buttermilk, we have to go back to the days when butter churners were household staples. When people made butter at home, they churned cream in butter churners and solids formed. That was the butter. The liquid that was left over was the buttermilk.The flavor was super rich and a little sour. In fact, cookbooks from the early 1900s used the terms buttermilk and sour milk interchangeably. People left it out for a few days to improve the flavor of the butter. Live cultures developed in the buttermilk, so it lasted longer than regular milk. In the days before refrigeration, this meant it could be kept around for cooking while people drank the fresh stuff. So, how is buttermilk made these days? It’s cultured. 

What’s cultured buttermilk? 

Sorry, it’s not the college thing. It’s regular milk, with live active bacteria cultures added. The culture makes it a little thicker and gives the flavor that tang. This is the stuff you see at most stores. Those live cultures can be added to any type of milk, from low-fat to whole milk. Most buttermilk on store shelves is low on fat. So there you have it, there’s no butter in there. What is buttermilk made of? Just water, milk proteins, lactose, fat, and bacteria.

What is buttermilk used for? 

Besides just drinking it, people use buttermilk in many recipes. It’s a popular ingredient in Southern U.S. cooking, and it  is the go-to ingredient when you want to make your quick bread recipes extra fluffy. Chefs use buttermilk to make pancakes, waffles, biscuits, and muffins because that tanginess provides acidity to undercut and balance the sweetness in recipes and the fermentation activates baking soda, producing the gas to make the dough rise. If you’re making a recipe that uses buttermilk and you don’t have any, you can actually substitute regular milk and lemon juice or white vinegar.

So get out your butter churners. Pour yourself a big glass of sour milk. Crank up the stereo and blast the “flies in the buttermilk, shoo fly shoo” section from “Skip to My Lou” while you make some pancakes. And let’s be thankful that some weirdo figured out bacteria milk was useful.