Optimal kinetic parameters and batch modeling for pectin hydrolysis to galacturonic acid with Pectinex Ultra SP-L enzyme

Galacturonic acid is a monosaccharide obtained by pectin hydrolysis and a suitable substrate to produce bioethanol by fermentation. This paper focuses on quantification of citrus pectin hydrolysis to galacturonic acid and provides new, reliable kinetic parameters for the Michaelis-Menten equation when the well-known, commercial Pectinex Ultra SP-L is employed as enzyme. They are: rmax=1.10 g/ (L min), Km=10.42g/L and KIGA=10.05g/L, as obtained with a great accuracy by a non-linear regression method and confirmed by the three classical linearization procedures (Lineweaver-Burk, Langmuir and Eadie-Hofstee). The quantification of product inhibition has been achieved, with its inclusion in the rate equation. A batch reactor model yields a perfect agreement between predictions and experiments, even under conditions different from those on which the parameters had been determined by regressio