Much American butter has in the past been criticised by commercial judges on account of containing too much moisture (leaky butter, as butter judges term it), when, in reality, it showed by chemical analysis only a low percentage of water. This is undoubtedly due to improper incorporation of the moisture, as much butter, apparently dry, contains a high moisture content.
It is also a well known fact that the amount of butter which is being made from a given amount of fat varies a great deal at the different creameries. Some makers are able to produce only 110 pounds of butter from 100 pounds of fat, while some other makers are able to produce 120 pounds of butter of equal commercial quality from the same amount of fat; that is, some are able to get an overrun of only about ten per cent, while some others obtain an overrun of about 20 per cent.
McKay, G. L. and Larsen, C.
"The moisture content of butter and methods of controlling it,"
Bulletin: Vol. 7
, Article 1.
Available at: https://lib.dr.iastate.edu/bulletin/vol7/iss76/1