Modeling of the enzymatic synthesis of fructo-oligosaccharides

M MICAELA URETA; FAROUX, J.M.; ANDREA GÓMEZ-ZAVAGLIA; V. O. SALVADORI

Congreso; 11th World Congress of Chemical Engineering; 2023

Fructo- and galacto-oligosaccharides (FOS andGOS) are widely known products because of their prebiotic properties. Inaddition, they have relevant nutritional characteristics, being low caloricsweeteners, with low glycemic index and not cariogenic.As prebiotics, they are incorporated in manyproducts, such as dairy products, beverages, bakery, and infant formula.The production of FOS is a complex processthat involves different transfructosylation reactions of synthesis andhydrolysis occurring simultaneously. Short chain FOS are mixtures of smallestoligosaccharides, represented by 1-kestose (DP3), nystose (DP4) and1-fructofuranosylnystose (DP5). In previous experimental work, the conditionsfor the enzymatic synthesis of FOS were studied, using commercial sucrose asraw material and Vizcozyme L as the biocatalyst. The influence of the initialconcentration of sucrose solution (40% and 50% w/vol), temperature, and reactiontime (4 to 24 h) was investigated. The experiments were performed in a labscale fermenter (5 l) and also at pilot plant scale (50 l). The composition ofthe reaction product was analyzed by HPLC. The aim of this work is the simulation of thewhole process of FOS synthesis, that allows to perform the scale up from thepilot plant to an industrial scale. As a first step of the simulation, a modelof the coupled set of reactions is needed.Based on previous models available inliterature [1], a Michaelis-type mechanism of four enzymatic reactions isproposed, with sucrose (S) as the main reactive, and glucose (G), DP3, DP4 andDP5 as the reaction products. The inhibition effect of sucrose and thecompetitive inhibition of glucose were considered in the reactions.Thekinetic parameters of the enzymatic reactions were determined as an inverseproblem solution, with the experimental composition of FOS as model input.Since the reactions are described by a set of ordinary differential equations(ODEs), the non-linear least square fitting procedure was coupled to a 4thorder Runge-Kutta method solved with a MATLAB routine. Very good agreement wasfound in the fitting procedure which indicates the adequacy of the proposedmechanism. Once the reactions are characterized, the next step is thesimulation of the reactor.