title: Isomerization of lactose-derived oligosaccharides: a case study using sodium aluminate.
abstract: Galactooligosaccharides (GOS) obtained during the enzymatic hydrolysis of lactose contain large amounts of glucose, galactose, and unreacted lactose, which do not have prebiotic properties and increase the calorific value of the product. In this work, the isomerization of the GOS mixture by the action of sodium aluminate has been studied. During the reaction, lactose, glucose, and galactose were isomerized to lactulose, fructose, and tagatose, respectively, and in addition allolactose, 6-galactobiose, and 6'-galactosyl-lactose were also converted to the corresponding keto-sugars. The effect of time, temperature, and aluminate/initial lactose ratio has been studied. After 9 h at 40 degrees C and molar ratio aluminate/lactose 3:1, the isomerization yield was >60%, and the amount of final carbohydrates was close to 90% of the initial product. This process considerably decreases the amount of lactose, glucose, and galactose.
authors.affiliation: Instituto de Fermentaciones Industriales, CSIC, Juan de la Cierva 3, Madrid, Spain.
authors.forename: Alejandra
authors.initials: A
authors.lastname: Cardelle-Cobas
authors.forename: Nieves
authors.initials: N
authors.lastname: Corzo
authors.forename: Mar
authors.initials: M
authors.lastname: Villamiel
authors.forename: Agustín
authors.initials: A
authors.lastname: Olano
mesh_terms: D017607:Aluminum Compounds / Q000737:chemistry*; D002384:Catalysis; D005690:Galactose / Q000032:analysis / Q000737:chemistry; D005947:Glucose / Q000032:analysis / Q000737:chemistry; D007536:Isomerism; D007785:Lactose / Q000032:analysis / Q000737:chemistry*; D009844:Oligosaccharides / Q000737:chemistry*; D017670:Sodium Compounds / Q000737:chemistry*
chemical_list: D017607:Aluminum Compounds; D009844:Oligosaccharides; D017670:Sodium Compounds; C539561:sodium aluminate; D005947:Glucose; D007785:Lactose; D005690:Galactose