title: Enzymatic production of lactulose and 1-lactulose: current state and perspectives.
abstract: Lactulose, a synthetic ketose disaccharide, has been widely used in food and pharmaceutical industries as prebiotic food additives and drugs against constipation and hepatic encephalopathy. Lactulose has, so far, been produced chemically using lactose on a commercial scale. The key problems associated with such chemical process are the cost of removal of the catalyst and colored by-products and the product safety. Enzymatic production of lactulose is safe, environment-friendly, and simpler in comparison to the chemical method. As a promising alternative to the chemical method, enzymatic conversion of lactose into lactulose by β-galactosidase or cellobiose 2-epimerase has recently gained a great deal of attention. This could be considered as a possible route for whey surplus because lactose is the major component of cheese whey. Herein, we summarize recent advances on the enzymatic synthesis of lactulose with emphasis on the selectivity of biocatalysts and their catalytic efficiency in free and immobilized forms. The production of 1-lactulose by enzymatic bioconversion of lactose has also been discussed. Furthermore, future research needs of β-galactosidase and cellobiose 2-epimerase for the enzymatic synthesis of lactulose and 1-lactulose are reviewed.
authors.affiliation: State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, Jiangsu, People's Republic of China.
authors.forename: He
authors.initials: H
authors.lastname: Wang
authors.forename: Ruijin
authors.initials: R
authors.lastname: Yang
authors.forename: Xiao
authors.initials: X
authors.lastname: Hua
authors.forename: Wei
authors.initials: W
authors.lastname: Zhao
authors.forename: Wenbin
authors.initials: W
authors.lastname: Zhang
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D001711:Biotransformation; D005656:Fungal Proteins / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D007218:Industrial Microbiology / Q000379:methods / Q000639:trends*; D007792:Lactulose / Q000737:chemistry / Q000378:metabolism*; D019998:Racemases and Epimerases / Q000737:chemistry / Q000378:metabolism*; D001616:beta-Galactosidase / Q000737:chemistry / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D005656:Fungal Proteins; D007792:Lactulose; D001616:beta-Galactosidase; D019998:Racemases and Epimerases