Determination of the mass fraction of lactose in milk and milk products.
The method for determination of lactose contents is based on the hydrolysis of lactose contained in the aqueous extract of a sample of milk or milk products relieved from fat and protein, in the presence of β-galactosidase to glucose and galactose, through oxidation of galactose contained in the sample under the effect of β-nicotinamide adenine dinucleotide in the presence of an enzyme of β-galactose dehydrogenase and using the photometric measurement of mass fraction of the formed β-nicotinamide adenine dinucleotide (reduced form) which is equivalent to the mass fraction of galactose, as well as calculation of the mass fraction of lactose by the difference of optical densities of the given solution and the solution used during the determination of free galactose.
To carry out the analysis, we use the Lactose/D-Galactose diagnostic kit made by Roshe Diagnostics GmbH (Germany).
