β-Galactosidase from Talaromyces thermophilus immobilized on to Eupergit C for production of galacto-oligosaccharides during lactose hydrolysis in batch and packed-bed reactor

The beta-galactosidase from Talaromyces thermophilus CBS 236.58 immobilized onto Eupergit C produced galacto-oligosaccharides (GalOS) in batchwise and continuous packed-bed mode of operation. A maximum yield of GalOS of 12, 39 and 80 g l(-1) was obtained for initial lactose concentrations of 50, 100 and 200 g l(-1), respectively, for batch conversion experiments. The immobilized enzyme could be re-used for several cycles for lactose hydrolysis and transformation. The maximum GalOS concentration of approximately 50 g l(-1) was obtained with the dilution rate of 0.375 h(-1) in a packed-bed reactor, when using an initial lactose concentration of 200 g l(-1). Continuous conversion of lactose in the packed-bed reactor resulted in the formation of relatively more trisaccharides than when employing the immobilized enzyme in discontinuous mode of operation.