Lactose is the primary carbohydrate found in mammals’ milk and is often referred to as milk sugar. It is the first and only carbohydrate every newborn mammal consumes in significant amounts.

Lactose is a natural disaccharide consisting of one galactose and one glucose unit. It is chemically, physically and microbiologically stable and highly compatible with other ingredients. Lactose forms the major part of milk’s dry matter content.

Lactose is derived by isolating it from dairy products such as whey and whey permeate after they are generated in the production of cheese and/or caseinates. The key process in lactose production is evaporating the water in whey to increase lactose concentration. The condensed whey, with about 60% total solids at 140ºF (60ºC), is then gradually cooled. As it cools, the lactose in whey crystallizes and can be separated out.

Various types of lactose can be produced in this fashion. Separation of the crystal mass and subsequent drying results in a yellow or yellowish-colored product called edible lactose. It still contains a small amount of whey proteins and minerals. The yellow color is caused by riboflavin. Refining of this product results in what is known as refined edible lactose. The purest form of lactose, which is used in the pharmaceutical industry, is obtained by repeated refining.

Lactose is commercially available as spray-dried lactose and crystalline lactose. Lactose derivatives include lactose hydrolysates, lactitol, lactulose and lactobionic acid.

Nutritional information
Lactose is a carbohydrate, contributing about 4 calories per gram. Research suggests that lactose promotes the growth of beneficial lactic acid-producing bacteria that compete with undesirable putrefactive bacteria.

While the presence of lactose stimulates the intestinal absorption of calcium in laboratory animals and human infants, there is no evidence that it improves calcium absorption in adults, according to the Handbook of Dairy Foods and Nutrition, Second Edition.