Many, many years ago, but buttermilk was made by using the liquid that was leftover at the bottom of the butter churn after the butter had been churned. So this is why it has its original name of buttermilk.
Nowadays, buttermilk is made with a much different process. Today they’re usually using a lactic-acid bacterial culture and adding it to pasteurized whole milk and using it to turn the milk into today’s version of buttermilk.
Buttermilk can still be made the old-fashioned way, but you need to have a churn or some other set up with a large jar that you can replicate the same kind of scenario. That said, it is definitely a lot of work, and a lot of physical work since you’re either churning or shaking to make your butter and buttermilk.
