Overview

Lactose (LAK-tose) is a white, odorless, sweet-tasting solid commonly known as milk sugar because it occurs in the milk of many animals, primarily the mammals. The lactose content of milk ranges from about 2 to 8 percent in cows and 5 to 8 percent in human milk. Lactose occurs in two isomeric forms, α-lactose and β-lactose, with the latter somewhat sweeter than the former. The alpha form tends to occur as the monohydrate, C₁₂H₂₂O₁₁·H₂O.

Key Facts

Other Names:

D-lactose; milk sugar; many others

Formula:

C₁₂H₂₂O₁₁

Elements:

Carbon, hydrogen, oxygen

Compound Type:

Disaccharide; carbohydrate (organic)

State:

Solid

Molecular Weight:

342.30 g/mol

Melting Point:

222.8°C (433.0°F)

Boiling Point:

Not applicable; decomposes

Solubility:

Very soluble in water; slightly soluble in ethyl alcohol; insoluble in organic solvents

How It Is Made

Lactose is synthesized in the mammary (milk-producing) glands of mammals. The milk of such animals contains an enzyme...