The modern process of making buttermilk and butter begins when cream is removed from pasteurized whole milk in continuous centrifugal separators spinning at 30,000 RPM. The resulting cream contains 40% butterfat, and is known as heavy, or whipping, cream. From the separator, the heavy cream travels directly into continuous “ribbon” churns, which process it into sweet cream butter and high-fat buttermilk. The buttermilk is high fat because ribbon churns are not very efficient at churning all of the butterfat into butter. This buttermilk is then re-separated to remove the excess butterfat, and dried for industrial applications such as commercial ice cream and baking products, as well as consumer packaged goods like buttermilk pancake and baking mixes. The butter made this way is called “sweet cream” butter because the cream it was made from was not cultured or acidified.

This differs substantially from the traditional method of making butter, both in the butter-making process itself and in the flavor of the butter produced. Dairy production used to take place on family farms and in small creameries, and butter was always made in small batches. Back then, once the cream was separated from the milk, it was put into holding tanks for up to a day before it was churned into butter. This allowed the cream to settle from the agitation of the separation process and gave the butter-maker time to culture his cream.

The cream was cultured before churning for two very practical reasons. Heavy cream is 40% butterfat and 60% milk solids and water. Adding a lactic acid-producing culture to acidify the cream before churning helped to separate these two components during the churning process. As the butterfat solidified as butter in the churn, the fluid that was drained away became known as “buttermilk,” the by-product of butter-making.

Adding live cultures to the cream also yielded a more “pure” butter, as they consumed proteins in the milk solids to produce lactic acid. This added to the storage life of butter, because any remaining milk proteins could ferment or “spoil,” making the butter rancid. To further prevent spoilage, the butter-maker would also wash the butter with water after churning to remove residual milk solids.

In addition to these practical benefits, culturing the cream before churning gave the butter a unique flavor—very different from the flavor of today’s supermarket butter. Before the advent of the large commercial dairies, Minnesota and Wisconsin used to be dotted with small creameries, each with its own particular flavor of butter made from closely guarded family cultures.

These cultures ended up in the churned buttermilk, as well. Although buttermilk initially resembles skim milk when it is removed from the butter churn, the continuing action of the live cultures creates the tart, thick beverage that we know as buttermilk. Before the days of refrigeration, the consistency of buttermilk would change with the seasons: thin and less tart during winter and thick and clabbered in the summertime.

Buttermilk’s taste and texture made it a remarkable beverage, but what permanently endeared it to America’s cooks were its properties as a baking ingredient. Real buttermilk’s “real” benefits begin at the moment that butterfat becomes butter in the churn.

Batch-churning cream into butter takes about 30 minutes, but it is only in the last few minutes that the butter begins to form. The mechanical agitation of the churning process breaks down an emulsifying membrane around droplets of butterfat, allowing the butterfat to solidify as butter.

Fat and water don’t ordinarily mix, but this emulsifying membrane, a molecule called a phospholipid, has the ability to attach itself to both fat and water molecules, thus keeping the butterfat liquid in the cow, as well as in cream and whole milk. Once stripped from the butterfat during churning, these now “free” emulsifiers become part of the buttermilk.

When used for cooking and baking, the emulsifiers in real cultured buttermilk attach to both the liquid and the shortening in the recipe, evenly dispersing the fat in very fine particles throughout the batter. This results in a lighter, more uniform texture and fine crumb. In addition, the acidity from the culturing process combines with other leavening ingredients in the recipe to create baked goods with superior volume. But ultimately the phospholipids and their emulsifying properties are the reason buttermilk has been so esteemed among cooks and bakers for generations.

However, with the modernization of America’s dairy industry in the 1940’s and 50’s came the introduction of continuous churns and the demise of cultured butter and real cultured buttermilk. Modern “buttermilk” is made by adding lactic acid-producing cultures directly to skim milk, rather than to the cream that is churned into butter and buttermilk.

Although it’s somewhat misleading, “buttermilk” became the widely used term for cultured skim milk, and even though it doesn’t contain a drop of real buttermilk, the name was “grandfathered” into current usage. If introduced now, it would never pass present-day labeling requirements.

Another reason that the modern dairy industry made the switch from buttermilk to cultured-skim is that it takes a lot of milk to make a small amount of real buttermilk. For example, one gallon of milk yields about 7 1/4 pints of skim milk and 3/4 pint of heavy, 40% cream. The 3/4 pint of heavy cream can be churned into 1/3 lb. of butter (1 1/2 sticks), and about 1/2 pint (1 glass) of buttermilk. So, 1 gallon of milk yields only about 8 ounces of real buttermilk, but 116 ounces of skim milk that can be cultured and sold as “buttermilk”!

While cultured skim milk has a similar taste and texture to real cultured buttermilk, it has none of the emulsifying properties that made the old-fashioned buttermilk such a prized ingredient for cooking and baking. However, SACO Cultured Buttermilk Blend is made from real sweet cream, churned buttermilk, so it contains the natural emulsifiers that improve the volume, texture, and aroma of baked goods.