Lactose is sugar naturally present in milk.
During cheese production, approx. 80-90% of lactose moves into serum thus contributing to make up a part of it (approx. 5%).
Lactose is then recovered from serum in form of monohydrate alpha-lactose through processes of concentration (by evaporation), and crystallization.
Sugar extraction takes place by centrifugation; afterwards lactose is dried and ground.
There are three kinds of lactose: edible lactose, refined lactose, and pharmaceutical lactose, but, as a rule, American and European prices (see the table and graph below) refer to edible typology.
Thanks to its little sweetening power, lactose is applied in several edible preparation, especially chocolate and derivates, bakery and pharmaceutical products; it is also employed in the feed sector.
Furthermore, by means of special industrial processes as hydrolysis (enzymatic and catalytic splitting of lactose into glucose and galactose), enzymes treatment or other specific procedures (catalytic isomerization), starting from lactose many derived products can be obtained.
Among the best known and most important derivates are lactulose, lactitol and the GOS (galacto-oligosaccharides), used as prebiotics (substances intended to promote the growth of bifidobacteria and milk bacteria in the intestines) in many edible products.
The increased cheese production in the US generates as a consequence the availability of serum and, therefore, the possibility to extract a larger amount of lactose.
(This page has been realized with the contribute of Pier Luigi Vecchia, Food Technology expert)