Milk

Milk is a nutricious liquid mammals produce, in their mammary glands, to feed their young. That is the definition of mammal -- animals that have hair and feed their young milk.

Milk is white, or a pale yellow. It contains, proteins, lactose, and butter fat. The milk from different mammals contain differing amounts of butter fat. The milk from different mammals have distinctive tastes. The milk from marine animals can have very high butter fat content.

Globally, the milk from cows, is the primary choice for human consumption. Usually the cows are Holsteins, although Jersey and Guernsey cows also make high quality milk with slightly higher fat content. Goat's milk is also popular, particularly for cheeses.

Milk products

Humans harvest the milk of other animals, for human consumption. A dairy is where raw milk is processed. Dairy products include butter (cakes of fat), yogurt (milk altered by microorganisms), and cheese, (slabs of aged milk solids).

Untreated milk has to be consumed quickly, within about one day, or it will go sour, and be unpalatable.

Milk products, for human consumption, is processed, to make it last longer. Milk is almost always pasteurized, a process where it is heated, to kill the microorganisms it naturally contains as well as any contaminants. Milk, cream and butter are then refrigerated, and can remain palatable for weeks.

Ultrapasteurized milk is pasteurized at a higher temperature, and can be shelf-stable for longer.

Some milk is dried, to a powder, and, so long as it is kept dry, can remain palatable for years.

Unpasteurized cheese can spread Listeria monocytogenes, which can cause illness and miscarriages.

Milk chocolate requires milk as an ingredient. Many manufacturers use powdered milk. Hershey's uses fresh milk.

Butterfat content of the milk of various species

Butterfat content of the milk of various species

species	butterfat content	notes
Human	3.6 - 3.9
Mare	1.2-4.2
Cow	2.5-3.8
Sheep	5.9-6.9
Goat	3.1-5.2
Buffalo	6.0-15.0
Elephant	15
Sea otter	20-25
Walrus	30