Ultrafiltered milk (UF 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, permitting greater efficiency in cheese making. 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 and can benefit consumers if cost savings are passed on. However, U.S. milk producers are concerned that imported UF milk may displace domestically produced milk used to make cheese.
In 2008, HP Hood and Tuscan Dairy Farms began to sell UF milk by the half-gallon as Hood Simply Smart or (Tuscan) Over the Moon. It is marketed as skim milk that tastes just like 2%.