Kinetic modelling of scavenger reactions: Parameter estimation for a gallic acid-based oxygen scavenger
The software-based design of active packaging requires mathematical models of oxygen scavenger reactions. In this study we present a simple approach for describing such reactions with a second-order kinetic model and for determining the corresponding kinetic parameters. For the example of a gallic acid-based oxygen scavenger stored at 21â¦C and 0% RH, 75% RH and 100% RH, the model was fitted to oxygen absorption data using a downhill simplex-based algorithm for numerical optimization. As expected, the optimization results depended on the choice of the starting values. To identify the global optimum of the given parameter space, the results of multiple optimization runs with varying starting values were analyzed quantitatively. For the scavenger reactions at 75% RH and 100% RH unambiguous minima could be found. The reaction rate constants are 1.347Â·10â 7m3/(molÂ·s) and 1.496Â·10â 6m3/(molÂ·s) and the stoichiometric coefficients are 1.639 and 2.534 for 75% RH and 10 0% RH, respectively. However, at 0% RH, there was no detectable scavenger reaction and fitting the noisy experimental data led to ambiguous solutions without physical meaning. The analyzed method for the estimation of kinetic parameters can be applied for any scavenger reaction, thereby providing necessary information for active packaging design.