title: Continuous synthesis of lactulose in an enzymatic membrane reactor reduces lactulose secondary hydrolysis.
abstract: Newly developed parallel small-scale enzymatic membrane reactors (EMRs) were used to enhance the synthesis of lactulose using β-galactosidase. Under batch operation, the productivity of lactulose decreased abruptly from 2.72 down to 0.04 mg lactulose/(Uenzymeh) over 35 h of reaction. This was presumably caused by the action of β-galactosidase which performed secondary hydrolysis upon the produced lactulose. The continuous operations of an EMR system led to continuous removal of lactulose in the reactors restricting lactulose degradation caused by secondary hydrolysis. Therefore, continuous lactulose syntheses in the EMRs yielded significantly higher specific productivities under "steady state" conditions. Approximately 0.70 and 0.50 mg lactulose/(U enzyme h) for hydraulic residence times of 5 and 7h were reached, respectively. Continuous lactulose synthesis performed in an EMR system conclusively can circumvent the drawbacks (e.g., secondary hydrolysis) of lactulose synthesis encountered in batch operation. It is, therefore, beneficial in terms of enhanced lactulose productivity and reduced enzyme consumption.
authors: Chair of Chemical and Process Engineering, Technische Universität Berlin, Ackerstraße 76, 13355 Berlin, Germany; Department of Food Science and Technology, Bogor Agricultural University, Raya Darmaga St, Kampus IPB Darmaga, Bogor 16680, West Java, Indonesia. Electronic address: azis.b.sitanggang@mailbox.tu-berlin.de.
authors: Azis Boing
authors: AB
authors: Sitanggang
authors: HTW Berlin - University of Applied Science, Engineering II, School of Life Science Engineering, Wilhelminenhofstraße 75A, 12459 Berlin, Germany.
authors: Anja
authors: A
authors: Drews
authors: Chair of Chemical and Process Engineering, Technische Universität Berlin, Ackerstraße 76, 13355 Berlin, Germany.
authors: Matthias
authors: M
authors: Kraume
mesh_terms: D019149:Bioreactors; D006031:Glycosylation; D006868:Hydrolysis; D007716:Kluyveromyces / Q000201:enzymology; D007792:Lactulose / Q000096:biosynthesis*; D008567:Membranes, Artificial; D011312:Pressure; D013997:Time Factors; D001616:beta-Galactosidase / Q000378:metabolism*
chemical_list: D008567:Membranes, Artificial; D007792:Lactulose; D001616:beta-Galactosidase
keywords: Enzymatic membrane reactors (EMRs); Lactose; Lactulose; Transgalactosylation; β-galactosidase