Enzymatic modification of lactose

Lactose may be hydrolysed to glucose and galactose by enzymes (j8-galactosidases, commonly called lactase) or by acids. Commercial sources of -galactosidase are moulds (especially Aspergillus spp.), the enzymes from which have acid pH optima, and yeasts Kluyveromyces spp.) which produce enzymes with neutral pH optima. / -Galactosidases were considered to have 

Glucose-galactose syrups are about three times sweeter than lactose (70% as sweet as sucrose) and hence lactose-hydrolysed milk could be used in the production of ice-cream, yoghurt or other sweetened dairy products, permitting the use of less sucrose and reducing caloric content. However, such applications have not been commercially successful. 

The glucose moiety can be isomerized to fructose by the well-established glucose isomerization process to yield a galactose-glucose-fructose syrup with increased sweetness. Another possible variation would involve the isomerization of lactose to lactulose (galactose-fructose) which can be hydrolysed to galactose and fructose by some / -galactosidases. 

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