Everything You Ever Wanted to Know About Buttermilk

No, it’s not just you: Buttermilk is confusing. It’s confusing because the word “buttermilk” has meant different things at different times to different people. It’s confusing because different products labeled “buttermilk” today are similar in appearance and texture, but are actually made in different ways. It’s confusing because as a cultured (or fermented) food, buttermilk is just one member of a large, diverse family of sour dairy products. And buttermilk is especially confusing because one of its many varieties is known as “true buttermilk,” which implies that anything else is an imposter.

Ignore what’s true or false, right or wrong. It’s more helpful to simply look at the various forms of cultured dairy that have become known as buttermilk, how they’re made, and their history. Armed with that knowledge, you can decode any product on the shelf and find a buttermilk that works for your needs.

And buttermilk works for many needs: It makes everything from baked goods to salad dressing to meat taste amazing. There’s no reason you shouldn’t be able to use up a bottle. The bottom line is that getting to know buttermilk will improve your life. So buckle up, buttercup.

What even is buttermilk?

So glad you asked. There are two things commonly called buttermilk: One is the liquid byproduct of butter churning, while the other is a fermented liquid made from skim or whole milk.

Cultured buttermilk is what you will usually find on grocery store shelves. Similar to fermented yogurt drinks enjoyed around the world, cultured buttermilk is usually made from skim milk and inoculated with isolated “cream cultures.” You will also find whole-milk buttermilk, a similar product made with whole milk, which can lend the final product a thicker consistency and creamier flavor.

“I explain it as a drinkable yogurt,” says Colleen Cruze Bhatti, the co-owner of Cruze Farm, her family’s dairy farm in Knoxville, Tennessee. “It’s cousin to yogurt, cousin to kefir.” Though it’s used in numerous recipes, Cruze Bhatti insists that no one should cook or bake with cultured buttermilk that they wouldn’t drink on its own — we recommend doing so by dressing it up with some salt, spices, herbs, or fruit, as you might with lassi.

True buttermilk, on the other hand, is the liquid byproduct obtained from churning cultured cream into butter; it’s thinner than cultured buttermilk, with a more complex and less acidic flavor.

Beyond these two main categories, you might occasionally see sweet (cream) buttermilk — which is like true buttermilk but unfermented — or buttermilk powder, which is similar to powdered milk, but can be rehydrated to mimic the flavor and acidity, if not the texture, of liquid buttermilk. Made from cultured or sweet buttermilk, buttermilk powder is concentrated with an evaporator and then dried through spray-drying or roller-drying.

OK, but what’s all this talk about sour milk and cultures?

Time for a super-brief dairy history lesson.

According to Anne Mendelson, culinary historian and author of Milk: The Surprising Story of Milk Through the Ages, people drank sour milk for the majority of human history. This was by default: Before the advent of refrigeration, there wasn’t much time to drink or cook with milk before it started to turn, especially in warm climates.

Whether the milk came from a cow, goat, sheep, or buffalo, it was quickly besieged by lactic acid bacteria. Those microbes have a unique ability to digest lactose, a relatively rare type of sugar that’s found in dairy. From lactose, the microbes produce lactic acid, which both deters more harmful bacteria from spoiling the milk and lends sour dairy products their signature tart flavor, funky aroma, and thick texture.

Mendelson explains that dairying took off in the Near East around 8000 BCE alongside grain crops. From Mongolia to the Balkans, many regional cultures developed some form of butter (and with it, liquid byproducts that were an ur-buttermilk). Sometime around 3000 to 2500 BCE, genetic mutations allowed cattle to spread into hotter climates in South Asia, where cooks preferred to boil milk to create yogurt before churning, developing chaas. At the same time, livestock husbandry moved north and west through Europe, where colder temperatures cause milk to spoil more slowly, giving farmers time to let it sit overnight. Through gravity, the milk would naturally separate into skim milk and cream, the latter of which could then be churned into butter.

The conditions of those overnight hours in Europe were key to developing the buttermilk familiar today in the West. Whereas yogurt is heated to invite specific heat-loving microbes, buttermilk is made with bacteria that thrive at moderate temperatures. According to food science expert Harold McGee, the microbes responsible for European buttermilk take 14 to 16 hours to ferment milk at 72 degrees Fahrenheit, roughly the nighttime temperature in Eastern Europe during the summer, which was the natural milking season before manipulation allowed year-round milking.

So buttermilk comes down to bacteria?

While bacteria contribute lactic acid that provides tangy flavor, true buttermilk gets its unique texture from the process of churning cream into butter. Cream that rises to the top of milk has a high concentration of fat globules. When dairies churn the cream into butter, they smash these fat globules together, causing them to leak fat, which runs together into a solid mass of butter.

The leftover liquid after churning, true buttermilk, is packed with bits of globule membrane material, which gives buttermilk its je ne sais quoi. “[These] remnants of fat globule membranes are rich in emulsifiers like lecithin, and make it especially valuable for preparing smooth, fine-textured foods of all kinds, from ice cream to baked goods,” McGee explains. “It’s excellence for emulsifying led to the Pennsylvania Dutch using it as a base for red barn paint!”

How did buttermilk end up in so many American foods?

Buttermilk was not particularly respected among high-class European immigrants who came to America. “It was favored by a lot of lower-class people, but the lower-class people were Scots-Irish and enslaved Africans,” says food historian Michael Twitty. Among that latter group were the Fulani (Peul/Fulbe), a nomadic, pastoral ethnic group spread across Africa from Senegal to Sudan.

“They are the cattle people,” Twitty says. “They revere the cow.” In addition to cheese and butter, the Fulani had a lot of experience with buttermilk, which they drank as a prized beverage, used in porridge with millet and sorghum, mixed with rice, and baked into cakes and quick breads.

While enslaved Africans were certainly not the only cooks who translated buttermilk into American foods, Twitty says we can conclude that African Americans played a significant part in popularizing buttermilk in the South, part of the larger contribution made by slaves and their descendants to quintessential American foodways. “Buttermilk becomes part of the chicken cookery, part of the biscuit cookery. It’s cake. It’s pie,” he explains. “This is one of those foods and ingredients where the bridge between Africa, Europe, and America is very clear.”

Meanwhile, other scientific and commercial forces were at work. In 1846, Church & Co. (the company responsible for Arm & Hammer) debuted sodium bicarbonate as baking soda, marketing it as a quick, reliable replacement for yeast in risen baked goods. Unlike baking powder, which comes preloaded with an acid, baking soda must interact with an external acid to produce carbon dioxide gas. The lactic acid in buttermilk was a good match, so Church & Co. popularized recipes for cornbread, biscuits, muffins, pancakes, and waffles featuring buttermilk in combination with baking soda.

Wow, who knew we use this super-special butter byproduct in all these foods?

Hold on a minute there, partner. Remember how we said there were two main kinds of buttermilk? Well, the butter byproduct kind is pretty rare these days. Most of what’s on the shelf is “cultured buttermilk.”

According to McGee, most dairy producers make cultured buttermilk with a method similar to that used to make yogurt, which relies on the chemical interaction between two kinds of proteins: casein (curds) and lactoglobulin (whey). Heating the buttermilk like yogurt before fermenting it helps to stabilize and evenly disperse the proteins into a thick slurry, preventing it from breaking into liquid and clumps.

How did we get cultured buttermilk in the first place?

In 1878, the Swede Carl Gustaf de Laval patented a centrifugal separator, which enabled dairies to separate components of milk without waiting for gravity to take their course. This allowed producers to churn cream before the microbes got to it, creating a byproduct similar to true buttermilk but without the acidic tang: sweet buttermilk.

At the same time, refrigeration began to spread, making naturally sour milk an increasingly rare commodity. To replace naturally soured dairy products, around 1900, scientists isolated and cultured the bacteria responsible for most fermented products, generally referred to as “cream cultures.” Not only could dairy producers use these cultures to inoculate their sweet buttermilk to make true buttermilk in a more consistent way, they could also add cultures to skim milk to create a drinkable and bakeable product similar to yogurt, as described above. (Today, any aspiring dairy producer can purchase a variety of cultures from companies like Vivolac Cultures Corporation.)

Just as a supply of cultured buttermilk was coming together, so too was demand. First, in 1904, biologist Élie Metchnikoff of the Pasteur Institute gave a lecture entitled “Old Age,” in which he argued beneficial bacteria from fermented dairy products could prolong life, kicking off a health craze over cultured milk in Europe and America. This was followed by a shortage of true buttermilk after World War II.

So all buttermilk is super healthy?

Unfortunately, the lactic acid bacteria used in most commercial buttermilk actually can’t survive in the human stomach, so buttermilk isn’t particularly healthy beyond basic nutritional value. However, if fat is a concern for you, many producers advertise buttermilk as low-fat, which is accurate for both cultured buttermilk from skim milk and true buttermilk. And since lactic acid nix lactose, they’re easier on the stomach for lactose-intolerant folks.

Is that where the story ends?

While cultured buttermilk still dominates store shelves, there are a growing number of products across the sour milk spectrum. Kate’s in Maine offers a taste of traditional true buttermilk that is much beloved by food writers of late. The buttermilk from Cruze Farm, meanwhile, is created by agitating cultured milk and cream together to produce both butter and buttermilk, making it a sort of hybrid. There are also now a number of brands selling whole-milk buttermilk, which creates a thicker, creamier product with less assertive acid.

So what the heck do I do with all of this buttermilk?

Baking: Buttermilk’s popularity across American demographics was built on baking. Combine it with baking soda to provide lift. Or plop it into a recipe where baking powder takes care of the rise to bring out buttermilk’s tang.

Deep frying: A batter made with a thickened liquid requires less flour, making for a more tender fried crust.

Salad dressing: You’ll often find buttermilk in salad dressings, where it acts as an emulsifier, contributing tang, body, and texture.

Brining: Like other acid marinades, buttermilk moistens and tenderizes meat.

A note of caution: Buttermilk is susceptible to curdling if you don’t treat it tenderly. Heat, salt, acid, and vigorous stirring can all spell disaster. Excess coagulation shrinks the protein network and squeezes out whey, resulting in an unpleasant, clumpy texture.

I’ve heard you can substitute buttermilk with—

Stop right there. We know where this is going, and it’s not a place you want to go. While you can get acid from substitutions like lemon juice or vinegar combined with milk, you probably don’t want to drink that mixture. Stella Parks tested a whole bunch of buttermilk subs (vinegar/lemon, buttermilk powder, plain yogurt) for Serious Eats, and found that most of them don’t perform particularly well in baking anyway. The only one that did okay was kefir, proving once again that cultured buttermilk is just drinkable yogurt.

I’m convinced buttermilk is amazing. Sounds like I have to buy it all the time now.

You can always DIY it. Mendelson provides a basic recipe for making butter and true buttermilk at home, but you can also culture an ersatz version of cultured buttermilk from the dregs of a commercial bottle, as long as the label indicates it contains active cultures. Just add a tablespoon of cultured buttermilk for each cup of milk, cover with cheesecloth, and let it sit at about 70 to 75 degrees for 12 to 24 hours until it thickens or “clabbers” (aka clobberin time).

Sophia Pappas is a Pittsburgh-based illustrator.