Ultrafiltered milk (UF milk), also known as diafiltered milk, is a subclassification of milk protein concentrate that is produced by passing milk under pressure through a thin, porous membrane to separate the components of milk according to their size. Specifically, ultra filtration allows the smaller lactose, water, mineral, and vitamin molecules to pass through the membrane, while the larger protein and fat molecule (key components for making cheese) are retained and concentrated. (Depending on the intended use of the UF milk product, the fat in whole milk may be removed before filtration.) The removal of water and lactose reduces the volume of milk, and thereby lowers its transportation and storage costs.
Ultrafiltration makes cheese manufacturing more efficient. Ultrafiltered milk is also sold directly to consumers under brands like fairlife and Simply Smart, who tout its higher protein content, lower sugar content, and creamier taste.
*Adapted from CRS Report for Congress: Agriculture: A Glossary of Terms, Programs, and Laws, 2005 Edition - Order Code 97-905, a document in the public domain.