Synthesis, kinetic analysis and modelling of galacto-oligosaccharides formation

• Published in: Chemical engineering research & design Vol. 130; pp. 154 - 166
• Main Authors: Mueller, I., Kiedorf, G., Runne, E., Seidel-Morgenstern, A., Hamel, C.
• Format: Journal Article
• Language: English
• Published: Rugby Elsevier B.V 01.02.2018; Elsevier Science Ltd
• Subjects: Catalysis; Chemical reactions; Chemical reactors; Chemical synthesis; Decomposition; Design optimization; Fermentation; Galactose; Galactosidase; Glucose; Kinetics; Lactose; Mechanistic kinetics; Model reduction; Modelling; Network analysis; Oligosaccharides; Organic chemistry; Parameter reduction and estimation; Perturbation experiments; Reaction kinetics; Sensitivity analysis; Singular value decomposition; Substrates; β-Galactosidase; Parameter reduction and estimation; Mechanistic kinetics; Modelling; Perturbation experiments; Network analysis; β-Galactosidase
• ISSN: 0263-8762; 1744-3563
• DOI: 10.1016/j.cherd.2017.11.038

[Display omitted] •Kinetic analysis of galacto-oligosaccharides (GOS) formation from lactose in a broad range of operating parameters.•Static and dynamic perturbation experiments performed to identify inhibition effects and reaction network.•Catalytic cycle postulated and mechanistic kinetic models for GOS synthesis based on Christiansen methodology derived.•Sensitivity analysis by parameter reduction techniques performed to reduce kinetic models to sensitive parameters only.•Model validation successful, provides basis for process development and optimization. To design and optimize chemical reactors and bio reactors a profound understanding of kinetics and in particular suitable mechanistic rate models is needed. In chemical reaction engineering the methodology from Christiansen considering elementary kinetics assuming rate-determining steps has been successfully applied. It is hardly considered for enzymatic reactions. In this work, kinetics of formation of the prebiotics galacto-oligosaccharides (GOS) from lactose were investigated with β-galactosidase using batch and dynamic experiments. The rates of the main and most relevant side reactions were quantified. Preliminary investigations were performed to determine the influence of pH, temperature, the amount of enzyme and the initial lactose concentration. To acquire mechanistic understanding instructive perturbation experiments were carried out dosing the substrate lactose and/or the products galactose and glucose either initially or dynamically during fermentation. Based on a postulated catalytic cycle, mechanistic kinetic models were developed considering hydrolysis of lactose, formation of GOS and inhibiting effects of the side products glucose and galactose. A sensitivity analysis was performed applying the subset selection method including model reduction based on singular value decomposition combined with rank revealing QR factorization. The parameterized mechanistic models allowed a good description of batch and dynamic experiments in a broad range of operating conditions.