LACTOSE

'Lactose' is a disaccharide that consists of β-D-galactose and β-D-glucose molecules bonded through a β1-4 glycosidic linkage. Lactose makes up around 2-8% of the solids in milk. The name comes from the Latin word for milk, plus the -ose ending used to name sugars.

Contents

Digestion of lactose

Melting point

Solubility

External links

Digestion of lactose

Infant mammals are fed on milk by their mothers. To digest it an enzyme called lactase (β1-4 disaccharidase) is secreted by the intestinal villi, and this enzyme cleaves the molecule into its two subunits glucose and galactose for absorption.
Since lactose occurs mostly in milk, in most species the production of lactase gradually ceases with maturity, and they are then unable to metabolise lactose. This loss of lactase on maturation is also the default pattern in most adult humans.[1] However, many people with ancestry in Europe, the Middle East, India, or parts of East Africa, maintain lactase production into adulthood. In many of these cultures other mammals such as cattle, goats, and sheep are milked for food.
This fact may cast doubt on some arguments by proponents of the Paleolithic diet, who argue that human metabolic needs have ''not'' changed since the last ice age. The process of retaining infant characteristics into adulthood is one of the simplest routes of adaptation, and is known as neoteny.

Melting point

The melting point of lactose is in a range of 200-202 degrees Celsius.

Solubility

8 g lactose per 10 g [2]
Lactose has a solubility of 1 in 4.63 measured %w/v. This translates to 0.216g of lactose dissolving readily in 1mL of water.
The solubility of lactose in water is 18.9049 g at 25 °C, 25.1484 g at 40 °C and 37.2149 g at 60 °C per 100 g solution. Its solubility in ethanol is 0.0111 g at 40 °C and 0.0270 g at 60 °C per 100 g solution. [3]

External links

★ Study Detects Recent Instance of Human Evolution (Finding that lactose ''tolerance'' is a recent change)