Original Research ARTICLE
The effect of deprotonation on the reaction kinetics of an oxygen scavenger based on gallic acid
- 1TUM School of Life Sciences Weihenstephan, Chair of Food Packaging Technology, Technical University of Munich, Germany
- 2Fraunhofer-Institut für Verfahrenstechnik und Verpackung (IVV), Germany
- 3Department of Food Engineering, Istanbul Technical University, Turkey
Oxygen scavengers based on gallic acid (GA) usually contain a base that establishes the alkaline conditions necessary for the humidity-induced scavenger reaction. Here we measured the effect
of sodium carbonate (Na2CO35 ) and sodium hydroxide (NaOH) on the reaction kinetics of such
scavengers. The time-dependent oxygen absorption of aqueous GA solutions (pH 2.9–13.8) was
determined and the results were described using a second-order kinetic model. We calculated
the degree of deprotonation (DoD) of GA in the solutions from the species distribution curves,
and assessed the effect of the DoD on the reaction kinetics. This revealed that both the reaction
rate coefficient k and the scavenger capacity n were significantly affected by the DoD. If the DoD
fell below 0.25, there was no significant reaction. Although k increased with the DoD, n reached
a maximum at DoD = 0.6-0.7. In principle, target DoD values can be achieved using any base,
but a strong base is more efficient because lower quantities are required. In our experiments,
the amount of Na2CO3 required to reach the maximum DoD was more than twice that of NaOH. Our results provide the basis for the functional design of active packaging systems incorporating optimized GA-based oxygen scavengers.
Keywords: active packaging, Food Packaging, polyphenol, 3,4,5-Trihydroxy benzoic acid[1-(pyridyl)ethylidene]hydrazone, Oxygen absorber
Received: 05 May 2019;
Accepted: 30 Sep 2019.
Copyright: © 2019 Pant, Özkasikci, Fuertauer and Reinelt. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Dr. Matthias Reinelt, Fraunhofer-Institut für Verfahrenstechnik und Verpackung (IVV), Freising, 85354, Bavaria, Germany, email@example.com