Preparation method of lactulose

The invention discloses a preparation method of lactulose, and belongs to the field of food biotechnology. In an aqueous two-phase system consisting of polyethylene glycol and phosphate, lactose is used as a single substrate, lactase and glucose isomerase are catalyzed jointly to generate lactulose, and purification is carried out by ion chromatography and crystallizationion, so that a lactulose concentrated solution is obtained. A novel method is provided for enzymatic preparation of lactulose. The preparation method of lactulose has the advantages of mild conditions, novel ideas, environmental friendliness and high practicability, which not only improves the conversion rate and purity of the product, reduces the production of by-products, simplifies the subsequent separation and purification process, but also achieves recycling of catalyst enzyme, and greatly reduces the production cost. 种乳果糖制备方法，属于食品生物技术领域。在由聚乙二醇与磷酸盐组成的双水相体系中，以乳糖为单底物，以乳糖酶和葡萄糖异构酶共同催化生成乳果糖，并通过离子色谱和结晶法纯化得到乳果糖浓溶液。为酶法制备乳果糖提供了种新的方法，本方法的优点是条件温和，思