A novel ceramic membrane reactor system for the continuous enzymatic synthesis of oligosaccharides

The continuous enzymatic production of galactosyl-oligosaccharides (GOS) from lactose as a substrate using a new type of ceramic membrane reactor system was investigated. GOS are non-digestible oligosaccharides and have recently attracted interest as prebiotics. However, the composition of oligosaccharides fraction and the variability in β-glycosidic linkages depend on the enzyme source. In the study presented below, native, physically immobilized, β-galactosidase from Kluyveromyces lactis (EC 3.2.1.23) was used as enzyme to catalyse transgalactosylation reaction to produce GOS, competed against the hydrolysis of lactose into its two component monosaccharides, glucose and galactose. To optimize GOS yielded, process conditions were varied: the average residence time of the enzyme was varied in the range of 13 to 24 min, the trans-membrane pressure (TMP) was in the range of 1 to 2 bar and the initial concentration of substrate was varied from 10 to 30% (w/w). Regarding the conditions investigated here, the maximum oligosaccharide concentration exceeded 38% (w/w) when the average residence time was 24 min, the TMP was 2 bar and an initial lactose concentration of 30% (w/w) was adjusted.