Galactooligosaccharides (GOS) are currently attracting considerable interest as prebiotic substances and can be prepared by transgalactosylation reactions from lactose using beta-galactosidase. We applied various combinations of the commercial beta-galactosidases, such as Nola Fit 5500, Saphera 2600 L, Maxilact LGI 5000 and Maxilact A4 MG to achieve the highest yield of GOS and reduced lactose content. The combination of the Maxilact LGI 5000 and Nola Fit 5500 resulted in amount of GOS 105 g L-1 with lactose content lower than 5 g L-1, whilst the combination of the Maxilact A4 MG and Maxilact LGI 5000 enzymes led to an increase in GOS to 141,1 g L-1 and decrease of the lactose content to 46,9 g L-1. The combination of enzymes produced a higher yield of GOS, reduced the concentration of lactose, eventually, increases the efficiency of galactooligosaccharides purification that could be potentially used in the further investigations. (C) 2019 Elsevier Inc. All rights reserved.