Since this project has been carried on primarily with the view of determining what will constitute a fair butter overrun it seems advisable first to explain what is understood by overrun and how it is determined.
Butter overrun is a term used to designate the number of pounds of butter that is made in excess of the pounds of butterfat used for its manufacture. It is generally spoken of as "percent overrun" which is expressed as equal to the number of pounds of butter made in excess of each 100 pounds of fat used for its manufacture, thus if 122 pounds of butter were obtained from 100 pounds of butterfat the percent overrun would be 22.
"Materials-balance method for determining losses of butterfat in the creamery,"
Research Bulletin (Iowa Agriculture and Home Economics Experiment Station): Vol. 27
, Article 1.
Available at: https://lib.dr.iastate.edu/researchbulletin/vol27/iss337/1