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Comparison of lignin derivatives as substrates for laccase-catalyzed scavenging of oxygen in coatings and films
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
Umeå Universitet. (Kemiska institutionen, Department of Chemistry,)
Umeå Universitet. (Kemiska institutionen, Department of Chemistry,)
Karlstad University, Faculty of Technology and Science, Paper Surface Centre. Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

Background: Lignin derivatives are phenylpropanoid biopolymers derived from pulping and biorefinery processes. The possibility to utilize lignin derivatives from different types of processes in advanced enzyme-catalyzed oxygen-scavenging systems intended for active packaging was explored. Laccase-catalyzed oxidation of alkali lignin (LA), hydrolytic lignin (LH), organosolv lignin (LO), and lignosulfonates (LS) was compared using oxygen-scavenging coatings and films in liquid and gas phase systems.

Results: When coatings containing lignin derivatives and laccase were immersed in a buffered aqueous solution, the oxygen-scavenging capability increased in the order LO < LH < LA < LS. Experiments with coatings containing laccase and LO, LH or LA incubated in oxygen-containing gas in air-tight chambers and at a relative humidity (RH) of 100% showed that paperboard coated with LO and laccase reduced the oxygen content from 1.0% to 0.4% during a four-day period, which was far better than the results obtained with LA or LH. LO-containing coatings incubated at 92% RH also displayed activity, with a decrease in oxygen from 1.0% to 0.7% during a four-day period. The oxygen scavenging was not related to the content of free phenolic hydroxyl groups, which increased in the order LO < LS < LH < LA. LO and LS were selected for further studies and films containing starch, clay, glycerol, laccase and LO or LS were characterized using gel permeation chromatograpy, dynamic mechanical analysis, and wet stability.

Conclusions: The investigation shows that different lignin derivatives exhibit widely different properties as a part of active coatings and films. Results indicate that LS and LO were most suitable for the application studied and differences between them were attributed to a higher degree of laccase-catalyzed cross-linking of LS than of LO. Inclusion in active-packaging systems offers a new way to utilize some types of lignin derivatives from biorefining processes.

Keyword [en]
Lignin derivatives, Laccase, Coating, Film, Oxygen scavenger
National Category
Chemical Sciences Chemical Engineering Industrial Biotechnology
Identifiers
URN: urn:nbn:se:kau:diva-28461OAI: oai:DiVA.org:kau-28461DiVA: diva2:635968
Available from: 2013-07-08 Created: 2013-07-08 Last updated: 2014-10-09Bibliographically approved
In thesis
1. Oxygen-reducing enzymes in coatings and films for active packaging
Open this publication in new window or tab >>Oxygen-reducing enzymes in coatings and films for active packaging
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Oxygen scavengers are used in active packages to protect the food against deteriorative oxidation processes. The aim of this work was to investigate the possibilities to produce oxygen-scavenging packaging materials based on oxygen-reducing enzymes. The enzymes were incorporated into a dispersion coating formulation applied onto a food-packaging board using conventional laboratory coating techniques.

Various enzymes were used: a glucose oxidase, an oxalate oxidase and three laccases originating from different organisms. All of the enzymes were successfully incorporated into a coating layer and could be reactivated after drying. For at least two of the enzymes, re-activation was possible not only by using liquid water but also by using water vapour. Re-activation of the glucose oxidase and a laccase required relative humidities of greater than 75% and greater than 92%, respectively.

Catalytic reduction of oxygen gas by glucose oxidase was promoted by creating an open structure through addition of clay to the coating at a level above the critical pigment volume concentration. Migration of the enzyme and the substrate was reduced by adding an extrusion-coated liner of polypropylene on top of the coating.

For the laccase-catalysed reduction of oxygen it was possible to use lignin derivatives as substrates for the enzymatic reaction. The laccase-catalysed reaction created a polymeric network by cross-linking of lignin-based entities, which resulted in increased stiffness and increased water-resistance of biopolymer films. The laccases were also investigated with regard to their potential to function as oxygen scavengers at low temperatures. At 7°C all three laccases retained more than 20% of the activity they had at room temperature (25°C), which suggests that the system is also useful for packaging of refrigerated food.

Place, publisher, year, edition, pages
Karlstad: Karlstads universitet, 2013. 91 p.
Series
Karlstad University Studies, ISSN 1403-8099 ; 2013:38
Keyword
Active packaging, food packaging, oxygen scavengers, oxygen-reducing enzymes, dispersion coating, biopolymers
National Category
Chemical Engineering
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kau:diva-28749 (URN)978-91-7063-516-8 (ISBN)
Public defence
2013-10-18, 9C204, Rejmersalen, Karlstad, 10:15 (English)
Opponent
Supervisors
Available from: 2013-09-27 Created: 2013-08-27 Last updated: 2014-10-27Bibliographically approved

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