58459-39-5Relevant articles and documents
Selective production of lactobionic acid by aerobic oxidation of lactose over gold crystallites supported on mesoporous silica
Gutierrez, Luis-Felipe,Hamoudi, Safia,Belkacemi, Khaled
, p. 94 - 103 (2011)
Partial oxidation of lactose over Au-based catalyst system using nanostructured silica materials with improved activity, selectivity and stability was investigated as a novel chemo-catalytic approach for selective synthesis of lactobionic acid (LBA) for therapeutic, pharmaceutical and food grad applications. Highly active gold crystallites dispersed on mesoporous silica (SiO2-meso) using bis-[3-(triethoxysilyl) propyl] tetrasulfide (BTSPT), a silane coupling agent to immobilize gold, were successfully formulated, and their catalytic activity was evaluated in an agitated semi-batch reactor. The catalysts were characterized by N2 physisorption, XRD, XPS and TEM. The influence of the reaction conditions, i.e., temperature, pH value, metal loading and catalyst/lactose ratio on lactose conversion were investigated. After 100 min of reaction, the catalyst containing 0.7% Au showed the highest catalytic activity (100% lactose conversion) and a 100% selectivity towards LBA, when it was used at a catalyst/lactose ratio of 0.2 under alkaline (pH 9.0) and mild reaction temperature (65 °C).
Gold as active phase of BN-supported catalysts for lactose oxidation
Meyer, Nathalie,Renders, Coralie,Lanckman, Rapha?l,Devillers, Michel,Hermans, Sophie
, p. 549 - 558 (2015/01/30)
Au/h-BN catalysts have been prepared by wet impregnation in order to combine the high activity of gold with the promising h-BN support to optimize the catalytic performances in lactose oxidation. After 1 h reaction, the catalysts were more active than all the Pd/h-BN catalysts described in previous works: 100% yield was reached after 2 h for a Au/h-BN catalyst prepared in water and containing only 1 wt.% of gold. The influence of α-Al2O3, γ-Al2O3 and Cblack as supports for Au was compared to h-BN and Au/α-Al2O3 was the most active. All of them exhibited 100% selectivity toward lactobionic acid. After a second run, Au/γ-Al2O3 presented a loss of selectivity and all were less active than during their first run. Au/h-BN and Au/α-Al2O3 have been regenerated and a thermal treatment permits to keep the catalysts active with 100% selectivity. Au/h-BN was the most active after regeneration thanks to the more facile poison removal from its surface and the high stability of boron nitride.
Production of lactose-free galacto-oligosaccharide mixtures: comparison of two cellobiose dehydrogenases for the selective oxidation of lactose to lactobionic acid
Maischberger, Thomas,Nguyen, Thu-Ha,Sukyai, Prakit,Kittl, Roman,Riva, Sergio,Ludwig, Roland,Haltrich, Dietmar
, p. 2140 - 2147 (2008/12/21)
Galacto-oligosaccharides, complex mixtures of various sugars, are produced by transgalactosylation from lactose using β-galactosidase and are of great interest for food and feed applications because of their prebiotic properties. Most galacto-oligosaccharide preparations currently available in the market contain a significant amount of monosaccharides and lactose. The mixture of galacto-oligosaccharides (GalOS) in this study produced from lactose using recombinant β-galactosidase from Lactobacillus reuteri contains 48% monosaccharides, 26.5% lactose and 25.5% GalOS. To remove efficiently both monosaccharides and lactose from this GalOS mixture containing significant amounts of prebiotic non-lactose disaccharides, a biocatalytic approach coupled with subsequent chromatographic steps was used. Lactose was first oxidised to lactobionic acid using fungal cellobiose dehydrogenases, and then lactobionic acid and monosaccharides were removed by ion-exchange and size-exclusion chromatography. Two different cellobiose dehydrogenases (CDH), originating from Sclerotium rolfsii and Myriococcum thermophilum, were compared with respect to their applicability for this process. CDH from S. rolfsii showed higher specificity for the substrate lactose, and only few other components of the GalOS mixture were oxidised during prolonged incubation. Since these sugars were only converted once lactose oxidation was almost complete, careful control of the CDH-catalysed reaction will significantly reduce the undesired oxidation, and hence subsequent removal, of any GalOS components. Removal of ions and monosaccharides by the chromatographic steps gave an essentially pure GalOS product, containing less than 0.3% lactose and monosaccharides, in a yield of 60.3%.
