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Item type:Publication, Access status: without files , Vergleich analytischer und sensorischer Methoden zur Beurteilung der Geruchsminderungsleistung eines Festbettadsorbers(Wiley-VCH, 2011-04-19); ; ; ; The odor emissions of a coffee processing company were reduced applying a fixed bed adsorber pilot plant. In order to evaluate the performance, breakthrough curves were determined using a flame ionization detector, portable electronic noses, olfactometry and analytical methods. The analytic identification of odorants and pollutants was carried out via enrichment on Tenax TA and on SPME fibers. Several odorants were identified, which determine the overall olfactory sensation. Furthermore the breakthrough behavior of different adsorbents was characterized. The olfactometric concept was applied first-time for the electronic noses.Publicationtype: Journal Article17 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Influence of reaction conditions on the enantioselectivity of biocatalyzed C-C bond formations under high pressure conditions(Elsevier, 2011-02-03); ; ; ; Benzoylformate decarboxylase (BFD, EC 4.1.1.7) is a homotetrameric thiamine diphosphate (ThDP)-dependent enzyme which catalyzes the synthesis of chiral 2-hydroxyketones accepting a broad range of aldehydes as substrates. In this study the synthesis of 2-hydroxypropiophenone (2-HPP) from benzaldehyde and acetaldehyde was catalyzed by three BFD variants namely BFD F464I, BFD A460I and BFD A460I-F464I. This paper reports the effect of hydrostatic pressure up to 290. MPa when the reactions were carried out at different benzaldehyde concentrations (5-40. mM) as well as at different pH values (7.0-8.5). Acetaldehyde concentration was fixed at 400. mM in all biotransformations. Reactions performed at high benzaldehyde concentrations and at high hydrostatic pressures showed an increase in (R)-2-HPP formation catalyzed by all BFD variants. For BFD A460I-F464I we observed an increase in the ee of (R)-2-HPP up to 80%, whereas at atmospheric conditions this variant synthesizes (R)-2-HPP with an ee of only 50%. Alkaline conditions (up to pH 8.5) and high hydrostatic pressures resulted in an increase of (R)-2-HPP synthesis, especially in the case of BFD A460I and BFD F464I.Publicationtype: Journal Article7 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Immobilization and characterization of benzoylformate decarboxylase from Pseudomonas putida on spherical silica carrierIf an adequate biocatalyst is identified for a specific reaction, immobilization is one possibility to further improve its properties. The immobilization allows easy recycling, improves the enzyme performance, and it often enhances the stability of the enzyme. In this work, the immobilization of the benzoylformate decarboxylase (BFD) variant, BFD A460I-F464I, from Pseudomonas putida was accomplished on spherical silica. Silicagel is characterized by its high mechanical stability, which allows its application in different reactor types without restrictions. The covalently bound enzyme was characterized in terms of its activity, stability, and kinetics for the formation of chiral 2-hydroxypropiophenone (2-HPP) from benzaldehyde and acetaldehyde. Moreover, temperature as well as pressure dependency of immobilized BFD A460I-F464I activity and enantioselectivity were analyzed. The used wide-pore silicagel shows a good accessibility of the immobilized enzyme. The activity of the immobilized BFD A460I-F464I variant was determined to be 70% related to the activity of the free enzyme. Thereby, the enantioselectivity of the enzyme was not influenced by the immobilization. In addition, a pressure-induced change in stereoselectivity was found both for the free and for the immobilized enzyme. With increasing pressure, the enantiomeric excess (ee) of (R)-2-HPP can be increased from 44% (0.1 MPa) to 76% (200 MPa) for the free enzyme and from 43% (0.1 MPa) to 66% (200 MPa) for the immobilized enzyme.Publicationtype: Journal ArticleScopus© Citations 5 11