Production of lactulose oligosaccharides by isomerisation of transgalactosylated cheese whey permeate obtained by β-galactosidases from dairy Kluyveromyces.

β-Galactosidases from Kluyveromyces lactis and Kluyveromyces marxianus isolated from artisanal ewes' milk cheeses, were used to transgalactosylate lactose from cheese whey permeate (WP). The content of galactooligosaccharides (GOS) obtained by transgalactosylation was comparable with that formed using pure lactose as substrate. In order to obtain a mixture with higher prebiotic oligosaccharide content, isomerisation of the transgalactosylated WP was carried out using sodium aluminate as catalyst.