Synthesis of galactooligosaccharides using sweet and acid whey as a substrate

Two commercial available lactases from Aspergillus oryzae and Kluyveromyces lactis were used to study the synthesis of galactooligosaccharides (GOS) in sweet and acid whey. At 38 g L-1 initial lactose concentration, the A. oryzae enzyme gave a GOS yield of 10.91 +/- 0.01% in lactose solution, 10.93 +/- 0.18% in sweet whey and 11.32 +/- 0.59% in acid whey. Thus, the components in whey did not influence the enzymes transgalactolytic activity. On the other hand, the K. lactis enzyme showed a strong dependence on whey type and whey concentration. At 38 g L-1 initial lactose concentration, GOS yields were 10.93 +/- 0.26% in lactose solution, 4.30 +/- 0.17% in sweet whey and 10.56 +/- 0.41% in acid whey. However, with increasing initial lactose concentration, the inhibitory effect of sweet whey was decreasing, which resulted in even higher yields than in lactose solution. (C) 2015 Elsevier Ltd. All rights reserved.