Preparation and characterization of gellan gum microspheres containing a cold-adapted β-galactosidase from Rahnella sp. R3

R-β-Gal is a cold-adapted β-galactosidase that is able to hydrolyze lactose and has the potential to produce low-lactose or lactose-free dairy products at low temperatures (4 °C). Cold-adapted enzymes unfold at moderate temperatures due to the lower intramolecular stabilizing interactions necessary for flexibility at low temperatures. To increase stability and usage-performance, R-β-Gal was encapsulated in gellan gum by injecting an aqueous solution into two different hardening solutions (10 mM CaCl2 or 10 mM MgCl2). Enzyme characteristics of both free and encapsulated R-β-Gal were carried out, and the different effects of two cations were investigated. R-β-Gal showed better thermal and pH stability after encapsulation. Ca2+ gels had higher encapsulation efficiency (71.4%) than Mg2+ (66.7%) gels, and Ca2+ formed larger inner and surface pores. R-β-Gal was released from the Ca2+ hydrogel beads more rapidly than the Mg2+ hydrogels during storage in aqueous solution due to the larger inner/surface pores of the matrix.