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Performance of an ultrafiltration membrane bioreactor (UF-MBR) as a processing strategy for the synthesis of galacto-oligosaccharides at high substrate concentrations.

Paper ID Volume ID Publish Year Pages File Format Full-Text
22763 43381 2016 10 PDF Available
Title
Performance of an ultrafiltration membrane bioreactor (UF-MBR) as a processing strategy for the synthesis of galacto-oligosaccharides at high substrate concentrations.
Abstract

•The performance of an UF-MBR for galacto-oligosaccharides synthesis was assessed.•Different processing conditions were tested using very high lactose concentrations.•Under optimal conditions, shear-stress and temperature did not affect the enzyme.•Long-term operation was limited by membrane fouling rather than enzyme denaturation.•UF-MBR increased the enzyme productivity with respect to a conventional batch system.

The performance of an ultrafiltration membrane bioreactor for galacto-oligosaccharides (GOS) synthesis using high lactose concentrations (470 g/L) and β-galactosidase from Aspergillus oryzae was assessed. Tested processing variables were: transmembrane-pressure (PT), crossflow-velocity (CFV) and temperature. Results showed that processing variables had significant effect on the yield, the enzyme productivity and the flux but did not on GOS concentration and reaction conversion obtained. As expected, the use of high turbulences improved mass transfer and reduced the membrane fouling, but the use of very high crossflow-velocities caused operational instability due to vortex formation and lactose precipitation. The use of a desirability function allowed determining optimal conditions which were: PT (4.38 bar), CFV (7.35 m/s) and temperature (53.1 °C), optimizing simultaneously flux and specific enzyme productivity Under these optimal processing conditions, shear-stress and temperature did not affect the enzyme but long-term operation was limited by flux decay. In comparison to a conventional batch system, at 12.5 h of processing time, the continuous GOS synthesis in the UF-MBR increased significantly the amount of processed substrate and a 2.44-fold increase in the amount of GOS produced per unit mass of catalyst was obtained with respect to a conventional batch system. Furthermore, these results can be improved by far by tuning the membranearea/reactionvolume ratio, showing that the use of an UF-MBR is an attractive alternative for the GOS synthesis at very high lactose concentrations.

Keywords
Lactose; Galacto-oligosaccharides; Membrane bioreactor; Ultrafiltration; High concentrations; β-Galactosidase
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Performance of an ultrafiltration membrane bioreactor (UF-MBR) as a processing strategy for the synthesis of galacto-oligosaccharides at high substrate concentrations.
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Biotechnology - Volume 223, 10 April 2016, Pages 26–35
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us