Synthesis of Galactooligosaccharides from Lactose by β-Galactosidase
Beta-galactosidase solution was obtained through the fermentation of Bacillus circulans SK28.003,and its powder was prepared from the concentration of its solution,salting and precipitation,and freeze drying.To increase the efficiency of transgalatosylation and GOS yields,the optimal reaction conditions,such as initial lactose concentrations,loading amount of the enzyme,temperatures and pH values of the buffer,were determined through single factor and orthogonal experiments.Using the yields of GOS as the evaluation index,the maximum GOS yield was achieved up to 45.5％ after 12 h synthesis when the reaction conditions were at 60 ℃,50 g/dL initial lactose concentration,6 U/g lactose in 0.1 M,and sodium phosphate buffer at pH 7.5.
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