Dairy cows are milked twice a day using mechanical vacuum milking machines. The raw milk flows through stainless steel or glass pipes to a refrigerated bulk milk tank.
a few hours of being collected. In the United States, there are several hundred thousand dairy farms and several thousand milk processing plants. Some plants produce only fluid milk, while others also produce butter, cheese, and other milk products.
Collecting
• 1 Dairy cows are milked twice a day using mechanical vacuum milking machines. The raw milk flows through stainless steel or glass pipes to a refrigerated bulk milk tank where it is cooled to about 40° F (4.4° C).
• 2 A refrigerated bulk tank truck makes collections from dairy farms in the area within a few hours. Before pumping the milk from each farm's tank, the driver collects a sample and checks the flavor and temperature and records the volume.
• 3 At the milk processing plant, the milk in the truck is weighed and is pumped into refrigerated tanks in the plant through flexible stainless steel or plastic hoses.
Separating
• 4 The cold raw milk passes through either a clarifier or a separator, which spins the milk through a series of conical disks inside an enclosure. A clarifier removes debris, some bacteria, and any sediment that may be present in the raw milk. A separator performs the same task, but also separates the heavier milk fat from the lighter milk to produce both cream and skim milk. Some processing plants use a standardizer-clarifier, which regulates the amount of milk fat content in the milk by removing only the excess fat. The excess milk fat is drawn off and processed into cream or butter.