I found this on the Internet today:
It discusses the way to make buttermilk and tells the difference between cultured buttermilk and 'old fashion' buttermilk.
I love buttermilk in any form but I especially remember the way I first had buttermilk on a relatives' farm where they milked their own cows and made their own butter.
The leftover from making butter is great!
In "olden times," farm families would let freshly milked milk sit for half a day and skim off the cream which had risen. This cream would be set aside in a cool place, around 50-60 F. Each milking's cream would be added until several gallons had accumulated. In the meantime, naturally occurring bacteria in the cream would cause it to slightly sour. This souring increases the efficiency of churning.
The accumulated, slightly sour, cream would be churned at the optimum temperature (approximately 58 F) such that the butter was firm enough to separate out, but soft enough to stick together into a mass. The butter was removed, washed in very cold water to remove the remaining milk, and salt worked in to preserve it.
The remaining liquid after the butter was removed was called buttermilk. I call it "old fashion buttermilk," which is slightly sour, has the consistency of milk, but is slightly paler. It has flakes of butter floating in it.
Commercial manufacturers sometimes add colored "butter flakes" to imitate the old fashioned buttermilk.
However, the two products are very different, cultured buttermilk being thick and tart, old fashioned being thin, and slightly acid, depending on how sour the cream got before it was churned."
Sure wish I could find some.