Buttermilk is one of those old-fashioned food items that are not that common in modern-day pantries. Outside of delicious buttermilk biscuits and pancakes, most Americans don’t have a lot of experience with the stuff. But even those that do might not realize that today’s buttermilk is a far cry from what their grandparents probably had.
Before the days of refrigeration and homogenization, people would leave their fresh milk sitting out for a period of time to let the cream and milk separate. The cream was then used to make butter and the liquid left over from the churning process is what’s considered “real” buttermilk. At least by one definition.
Prior to the 20th century, some people also referred to soured milk as buttermilk. This was in reference to the fact that milk sometimes went sour during the milk/cream separation phase. However, thanks to fermentation from the natural bacteria in milk, it was not “spoiled” so people would often still make butter from it. The resulting buttermilk byproduct would also be sour, which in turn created two separate categories of buttermilk – the kind that came from fresh cream was “sweet” buttermilk while the stuff from soured milk was “sour” buttermilk.
Soured milk was commonly consumed by many cultures throughout history, although in America, it was mostly poor farmers and slaves that drank it. They also often drank the buttermilk left behind from butter churning. These “sour” products likewise found their way into many recipes, particularly in the south where classics like buttermilk biscuits, buttermilk pie, and buttermilk cake originated.
Around the mid-1800s, the popularity of buttermilk spread beyond the South thanks primarily to the introduction of sodium bicarbonate, aka “baking soda.” First created by Church & Co. (which later introduced the Arm & Hammer brand), it was a reliable substitute for yeast in risen bread goods. However, unlike baking powder, it needed to be mixed with an acid in order to work. When it reacts with acid, carbon dioxide is released, which causes expansion of the batter and forms the characteristic texture and grain in cakes, breads, and other foods.
Church & Co. found that sour buttermilk was a perfect partner and via its cookbooks, the company helped spread the use of both ingredients to kitchens across America. In total, the company issued over 137 editions between 1860 and the early 1960s.
By the early 1900s as refrigeration became more widespread, sour milk and its byproducts became increasingly rare in most households. In the 1920s, “cultured” buttermilk was introduced to fill this gap and is the type that you are most likely to find in stores today. It is made with milk that has been pasteurized and homogenized, and then inoculated with a culture of bacteria that ferments the products.
You can still find old fashioned buttermilk today but it is not a common grocery store item. Most dairies today sell their butter byproducts to commercial food manufacturers who use the good stuff to add body and texture to various products. You can spot it in the ingredient list under “buttermilk solids.” However, the “sweet” varieties of buttermilk will not give you the bite that a soured product delivers. It also doesn’t always have enough acid to properly activate baking soda, so most often yields dry, flat baked goods.
A “sour” buttermilk is what’s needed for most recipes today, and the cultured stuff will give you virtually the same results as the real butter byproduct. Keep in mind that many recipes for buttermilk substitutes like mixing milk with lemon juice or vinegar typically don’t work out very well in baked goods. For cooks that like to use it but don’t necessarily keep it stocked, there is buttermilk powder available on the market, which lasts for a very long time. Cultured buttermilk also freezes exceptionally well. (Sources: Eater, New York Times, Slate)
