On Mon, 29 Jan 2018 19:10:08 -0800 (PST), dsi1 >
wrote:

>On Monday, January 29, 2018 at 11:36:00 AM UTC-10, U.S. Janet B. wrote:
>>
>> Actually, If you are lucky, you can still get buttermilk as a
>> by-product of churning butter. Otherwise, as you say, it is a
>> cultured product.
>> Janet US
>
>It makes perfect sense to call the liquid left after making butter "buttermilk." I've never had it nor have I seen such a thing in stores. My guess is that butter producers would have tons of that stuff on hand. What the heck do they do with it?

There is very little real buttermilk left from churning butter.
I have lifted a paragraph that explains the percentages from the Saco
site.

"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”!
Janet US