Re: How does a pioneer butter churn separate butter from milk?

Sorry to take so long but it is surprising difficult to find information about butter churning. Butter is made using large scrape-surface heat exchangers nowadays... but back to your question.

Butter is really being made from the cream portion of whole milk. There will be a liquid portion (buttermilk) left-over after you've churned the butter. So, it may look like it is going from a liquid to a solid, but that is really because you have to cool it at the same time as you churn it.

Let's think a little about emulsions, milk can be described as oil-in-water, but butter is really water-in-oil. The churning process helps you convert the one into the other by encouraging the milk fat globules to come together and form larger and larger globs. The milk fat solidifies as you cool it and sticks to itself, making the butter.

I think these links might be helpful for you to learn more about: Emulsions and Butter

or you can try finding these books (I didn't have much luck at my library but they sound helpful):
Making Cheese and Butter. by Phyllis Hobson.
Butter, by Susan Wake.

Hope this info helps!

Kieran