MODELLING IN VITRO MUSHROOM PPO KINETICS AT SUPERATMOSPHERIC OXYGEN CONCENTRATIONS

Kinetics of mushroom polyphenol oxidase (PPO, EC 1.14.18.1) with respect to oxygen concentrations from 5 to 100 kPa using chlorogenic acid (CGA) as a substrate were examined.
PPO activity was determined in bioreactors by measuring the oxygen consumption during the enzymatic reaction using a Clark-type oxygen electrode.
Obtained total oxygen depletion curves were fitted by a differential Michaelis-Menten equation.
The product concentration and superatmospheric oxygen concentrations had an inhibitory effect on the reaction rate.
A linear mixed inhibition model considering both the product (oxidised CGA) and the oxygen as inhibitors was developed.
A model with product as a competitive inhibitor and oxygen as an uncompetitive inhibitor was the most appropriate to explain the reaction kinetics.
The results indicate that superatmospheric oxygen concentrations could be effective in avoiding enzymatic browning caused by PPO. The methodology applied here has been shown as useful to study PPO activity at changing conditions by analysing depletion curves in total.

III International Symposium on Applications of Modelling as an Innovative Technology in the Agri-Food Chain; MODEL-IT

P.A. Gómez, S. Geysen, B.E. Verlinden, B.M. Nicolaï

browning, enzyme kinetics, linear mixed inhibition model, Michaelis-Menten

https://doi.org/10.17660/ActaHortic.2005.674.72