A new bioprocess for the production of prebiotic lactosucrose by an immobilized β-galactosidase

A new bioprocess for the synthesis of lactosucrose was studied using a covalently immobilized beta-galactosidase on macrospheres of chitosan. The effects of temperature and pH on the production of lactosucrose and other oligosaccharides were evaluated. At 30 degrees C and pH 7.0, the maximum concentration of lactosucrose reached to 79 gL(-1). The change of the reaction conditions allowed to modify the qualitative profile of the final products without quantitative change in the total of oligosaccharides produced. At pH 7 and 30 degrees C, products profile was 79 gL(-1) of lactosucrose, 37 gL(-1) of galactooligosaccharides and 250 gL(-1) of total oligosaccharides, while at pH 5 and 64 degrees C the concentrations for the same compounds were 40, 62 and 250 gL(-1), respectively. The immobilization increased the thermal stability up to 260 fold. Using 300 gL(-1) of sucrose and 300 gL(-1) of lactose, and 8.5 mg of chitosan mL(-1), 30 cycles of reuse were performed and the biocatalyst kept the maximal lactosucrose synthesis. These results fulfill some important aspects for the enzyme immobilization and oligosaccharides synthesis: the simplicity of the protocols, the high operational stability of the enzyme and the possibility of driving the final products. (C) 2017 Elsevier Ltd. All rights reserved.