Milk is a drink that can be found all over the world. It comes from a wide variety of animals, and has provided nutrition and health to man for thousands of years. It is produced by mammals in the mammary glands for nourishment of their young. Milk is a highly nutritious liquid that serves as the young mammals’ primary food source while their digestion is still unable to process other foods. Milk appears opaque and white, and is an excellent dietary source of calcium, protein, saturated fat and even vitamins such as vitamin C. The milk initially produced during lactation is known as colostrums, and this contains a large amount of maternal antibodies that provide the baby with protection from illnesses that may come from infective pathogens.
Milk also comes in a lot of varieties, which may depend not only of the animal of origin, but also on the process on how it was harvested and processed. Skim milk is the variety of milk that has an extremely low level of fat, so much so that is being marketed in some countries as “fat free” milk. The level of fat is negligible in skim milk, which makes it different from low fat and whole milk. The flavor is slightly different and has been described as bland and watery, however, and this is the trade off for the low fat content.
Skim milk has a fat content of less than 0.5%, significantly lower than low fat or semi-skimmed milk that contains approximately fat of 1-2%. Whole milk, on the other hand, comes with a fat content of 3.5%. Skim milk can sometimes be seen to have a very slightly greenish tinge to its opaqueness, because of the riboflavin that can be found in the whey component of milk. The casein micelles can also scatter light differently and give skim milk a slightly bluish tinge at times.
Milk is allowed to stand after milking, and fat consequently floats to the uppermost layer because of the difference in relative density. This very rich layer becomes butter and cream, and the rest is made into other processed dairy products such as cheese. However, if only the topmost fatty layer is removed and processed, and the remainder is known as skim milk because the fat has been “skimmed off” the milk. Centrifuges are now used to separate the fat from the rest of the milk.
Most dairy products, skim milk included, are pasteurized under high temperatures for safety. Milk is also homogenized, which improves the consistency of the milk by reducing all particles to a uniform size. Skim milk will remain viable if kept refrigerated for five to ten days, but it is a good idea to sniff the milk each time before drinking to avoid drinking spoiled products.
Skim milk is a healthy alternative for those looking for a milk substitute. Because of its low fat, it has become popular among those seeking to lose weight. The taste is similar enough for it to be used as a substitute for milk in a lot of food preparations, but the lowered fat content may not be useful in certain dishes. It can be used in coffees and teas to replace milk, however.