When a solution of Lactose is spray-dried, the rate of water removal is too rapid for crystallisation to occur. It exhibits minimal hygroscopicity, however, it is unstable, and will transform back to the α-Lactose form given the right conditions. This anomer forms small, kite-like brittle crystals that are brittle but also markedly more soluble. When Lactose is crystallised under standard processing conditions (typically 93.5 oC, anhydrous β-lactose is obtained. Various Lactose crystal forms can theoretically form. Lactose crystallises from solution when its equilibrium solubility is exceeded (for instance, through the removal of water or a lowering of temperature). At typical conditions, however, Lactose in solution is considered to be a mixture of α-, and β-Lactose. ![]() Changes in concentration or temperature can shift the equilibrium accordingly (for example, an increase in temperature or concentration increases levels of β-Lactose, and vice versa). The two forms have specific optical rotations 20 D of +89.4 o and +35 o, respectively, dur to their differences in the spatial positioning of a H-atom and the -OH-group on C1 in the glucose moiety.Ĭonversion between the two anomers occurs via the open chain form of the glucose moiety, and depending on the concentration and temperature, an equilibrium will establish at 20 D +55.3 o, corresponding to ≈37% α-Lactose, and 63% β-Lactose. Lactose exists naturally in the form of two isomers: α-Lactose (i.e β-D-galactopyranosyl-(1,4)-α-D-glucopyranose) and β-lactose (i.e β-D-galactopyranosyl-(1,4)-β-D-glucopyranose). To minimise risk from contamination from Bovine Spongiform Encephalopathy (BSE), additional refining and purification steps are undertaken, the result of a which are a chemically pure excipient that carries no risks arising from being an animal derived raw material. The process involves the crystallisation of a saturated whey concentrate. To date, milk is the only known significant source of lactose.įor pharmaceutical applications, Lactose is produced from whey as a by-product of the dairy industry. It is produced by the mammary epithelium of all lactating mammals. Lactose (IUPAC name of lactose is 4- O-(β-d-galactopyranosyl)-D-glucopyranose) is a naturally occurring disaccharide that consists of one molecule of β-D-galactose and one molecule of β-D-glucose molecules linked through a β1-4 glycosidic linkage. Lactose: Overview, Types and Key Properties It is supplied as white to off-white crystalline powder. ![]() ![]() It is described by official pharmacopoeia either as O-β-D-galactopyranosyl-(1,4)-β-D-glucopyranose or a mixture of O-β-D-galactopyranosyl-(1,4)-α-D-glucopyranose and O-β-D-galactopyranosyl-(1,4)-β-D-glucopyranose. Anhydrous lactose exists as either the α-lactose or β-lactose that is without its water of hydration, although the α-form is most often used in pharmaceutical applications.
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