Oxygen scavenging and aroma affecting

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Oxygen scavenging and aroma affecting enzymes
embedded in barrier coatings
Oxygen Scavenging and Aroma Affecting Enzymes
Embedded in Barrier Coatings Lars
JärnströmKarlstad UniversityDept. of Chemical
EngineeringSE-651 88 KarlstadSweden. Email
Lars.Jarnstrom_at_kau.se www.surftreat.kau.se
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Oxygen scavenging and aroma affecting enzymes
embedded in barrier coatings

• Outline
• Introduction to Nordic MINT
• Short overview of nanotechnology in barrier
  coatings
• Short overview of enzyme-based oxygen scavengers
• Presentation of a recently started project
  Oxygen Scavenging and Aroma Affecting Enzymes
  Embedded in Barrier Coatings (acronym ENZYCOAT)

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Karlstad University The University Campus
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NORDIC MINT - micro- and nanotechnology "Everyday
Nano"
Nordic MINT micro- and nanotechnology Everyday
Nano An initiative sponsored by Nordic
Innovation Centre 8 projects, 85 Nordic
organisations, 1 focus Focusing on increased
value products Integrating micro- or
nanotechnologies of today with existing
processes Combining Nordic efforts and
competences
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NORDIC MINT - micro- and nanotechnology "Everyday
Nano"
Nordic Innovation Centre The Nordic Innovation
Centre is the Nordic Council of
Ministers instrument for promoting an innovative
and knowledge-intensive Nordic business sector.
The Centre initiates and invests in
activities that enhance innovation capabilities
and develop and maintain a smoothly functioning
market in the Nordic region. The
Nordic Innovation Centre is located in Oslo. For
more information www.nordicinnovation.net
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NORDIC MINT - micro- and nanotechnology "Everyday
Nano"

• Nordic MINT micro- and nanotechnology
• Nordic Innovation Centre puts emphasis on the
  importance of building on already existing
  research. The approach is to point out practical,
  commercialisable applications that can be
  available and have impact on contemporary life
  well-being, health care and safety solutions.
• Achieving Nordic competitiveness within micro-
  and nanotechnology through Nordic MINT
• The main ambition of all Nordic MINT projects
  shall be to exploit existing competences and
  research results in order to
• Form essential and beneficial links between
  research and industry
• Capitalise on existing investments in
  technology and systems
• Involve and focus on the end-user product
  consumer or technology exploiter
• Develop increased value products
• Enhanced Nordic competitiveness

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Nanotechnology in barrier coatings
Nanocomposites are used in packaging technology
in order to reduce permeability of gases The
mechanism behind the enhanced barrier properties
is mainly due to the increase in the tortuosity
factor
The permeability decreases with increasing?
aspect ratio? volume fraction nanoparicles?
tortuosity factor and with decreasing?
permeability of the polymer matrix In most cases
the properties of polymer region near the mineral
surface differ from the bulk properties and this
factor may increase the permeability.
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Nanotechnology in barrier coatings
The most commonly used mineral in nanocomposites
is the clay mineral montmorillonote (closite,
bentonite) due to its high aspect ratio. TiO2 is
used in nanocomposites for UV-protection
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Nanotechnology in barrier coatings Structures of
clay-based nanocomposites
Conventional composite
polymer
nanoclay
Intercalated nanocomposite
Delaminated nanocomposite
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Nanotechnology in barrier coatings Effects of
carboxylation of barrier latex
Ultra-thin acrylate-rich shells on core-shell
barrier latex particles affected the permeability
similar to nano-sized minerals
AFM images show latex films (Tg 5C) heated to
30C
Carboxylated (5 methacrylic acid)
Non-carboxylated
Topography Phase
Topography Phase
The core-shell structure of the carboxylated
latex prevented coalescence and interdiffusion.
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Nanotechnology in barrier coatings Effects of
carboxylation of barrier latex
WVP - Water vapor permeability (WVP) of latex
films dried at different temperatures.Tg30C.
The non-carboxylated film was not measured at
100C.

Lower permeability in carboxylated film (stiff
network in the shell through hydrogen bonding)
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Enzyme-based oxygen scavengers
Why oxygen scavengers? The residual oxygen in a
food package is the main cause for food
deterioration. Oxygen is the main cause for food
deterioration due to oxidation of fats and oils
and growth of aerobic microorganisms. Oxygen is
well known to accelerate processes leading to
discolouration, slime formation, changes in
texture, rancidity and off-odour or off-flavour
problems.
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Enzyme-based oxygen scavengers
Glucose oxidase is a potential enzyme for
oxygen-adsorbing processes Glucose oxidase
catalyses the following reaction 2Glucose 2O2
2H2O ? 2Glucono-lactone H2O2 The produced
hydrogen peroxide is eleminated by
peroxidase/catalase 2H2O2 ? O2 2H2O The
presence of catalase is important for the
elimination of the produced hydrogen peroxide.
Mixed enzymes (glucose oxidase and catalase) are
commonly used. Two molecules of glucose are
needed to reduce one molecule of oxygen
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Enzyme-based oxygen scavengers
The enzyme-based oxygen absorbers can (in
principle) be produced as? sachets?
laminates? enzymes immobilized on PP and PE
films Commercially available O2-absorbing
sachets based on reactions catalysed by
food-grade enzymes exist on the market.
Bioka oxygen absorber (from http//www.bioka.fi)
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Enzyme-based oxygen scavengers

• In the case of laminates and films, the enzymes
  have to be immobilized in order to prevent
  contamination of the packed food.
• Immobilized enzymes are retained at the reaction
  site and do not contaminate the products
• Methods for immobilization of enzyme
• Adsorption
• Entrapment
• Covalent binding

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Enzyme-based oxygen scavengers

• Problems to be aware of
• The glucose oxidase is inactivated by
• the production of hydrogen peroxide
• changes in pH due to hydrolysis of gluconolactone
  to gluconic acid (occurs spontaneously)
• glucose molecules inaccessible for the enzyme
• inaccessible diffusion-limited substrate
• mutarotation (i.e. a-D-glucopyranose
  ß-D-glucopyranose)
• Some other additives of importance for the
  enzymatic activity
• CaCO3 (neutralization of gluconic acid)
• Water

Cf. Andersson. M., Andersson, T., Adlercreutz,
P., Nielsen, T. and Hörnsten, G., Toward and
enzyme-based oxygen scavenging laminate.
Influence of industrial lamination conditions on
the performance of glucose oxidase,
Biotechnology Bioengineering, 79(1), 37-42 (2002).
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ENZYCOAT
Oxygen Scavenging and Aroma Affecting Enzymes
Embedded in Barrier Coatings (acronym ENZYCOAT)
Overall objective Develop active packaging
films, for selective control of oxygen
transmission and odour formation, by dispersion
coating processes.
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ENZYCOATBackground

• Food spoilage due to oxidative processes
  producing off odours limit the shelf life of
  many foods.
• Enzymes can be used as oxygen scavengers.
• Aqueous dispersion coating can be performed at
  low temperatures with higher retention of
  enzyme activity?
• The large surface area of nano-particles
  (clays) provides an opportunity for enzyme
  immobilisation.
• Given the proper substrate enzymes can
  directly affect the formation and/or
  degradation of sensory active compounds.

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ENZYCOAT Partners

• Karlstad University, Lars Järnström, Sweden
• The Swedish Institute for Food and Biotechnology
  (SIK), Anders Leufvén, Sweden
• Danish Technological Institute, Paul Schlemmer,
  Denmark
• Norconserv AS, Morten Sivertsvik, Norway
• Matra / Technological Institute of Iceland,
  Magnús Gudmundsson, Iceland
• Tampere University of Technology, Jurkka
  Kuusipalo, Finland
• Borealis AS, Merete Skar, Norway
• Novozymes AS, Gitte Budolfsen Lynglev, Denmark
• Stora Enso Paperboard AB, Göran Bengtsson, Sweden
  
• Kemira Oyj, Johan Grön, Finland
• Korsnäs AB, Johan Larsson, Sweden
• Tetra Pak RD AB, Thorbjörn Andersson, Sweden

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ENZYCOAT Partners
Matra
Supported by
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ENZYCOAT Organization chart
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ENZYCOATSub objectives

• Research on the design of nanomaterial based
  processes using stable enzymes with a triggering
  mechanism as oxygen scavengers.
• Investigate the possible use of dispersion coated
  enzymes for active control of formation and/or
  degradation of sensory active compounds.
• Demonstrate the use of by-products from forest
  product industries for production of added value
  packaging.
• Design a model with active layers on paper,
  board, and plastic packaging materials.
• Apply for an EU-funded project.

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ENZYCOATProblem description (I)
The project will develop active barrier coatings
for application on paper, board and plastics min
order to get environmentally friendly active
packaging based on a combination of nano and
enzyme technology. Certain enzymes have been
shown to improve the shelf life of packed food,
acting as oxygen scavengers. Our approach is to
use water-borne dispersion coatings filled with
enzymes immobilized on nanoparticles. The nano
particles may also act as carriers of the
substrate. Further, the volume fractions of
nanoparticles and polymers will tune the
sub-micro porosity of the layers. The porous
structure will be used in order to tune the
accessibility of substrate and other important
features.
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ENZYCOATProblem description (II)
The nano technology approach is to modify the
surface of submicron- or nanosized minerals by
dispersing agents that also acts as substrates
for the oxidoreductase enzymes that will be used
in the study. The modification and immobilisation
of enzymes on the nanoparticles must not
negatively affect the colloidal stability. The
size of the enzymes themselves are typically in
the range of 20-30 nm.
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ENZYCOATproblem description (III)
The biotechnical approach in the project is to
use oxidoreductases and other enzymes consuming
oxygen. Glucose oxidase is the primary model
enzyme using glucose as substrates. If peroxide
is produced by the reaction, peroxidise/catalase
can be added. The substrate for the enzymes will
be carefully selected and distributed in the
coatings.
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ENZYCOAT Possible deliverables

• Development of coated sheets or films with active
  enzymes.
• Produce a box prototype based on enzymatic oxygen
  scavengers.
• Produce a flexible packaging prototype based on
  enzymatic oxygen scavengers.
• Give evidence for prolonged shelf-life using
  enzymatic oxygen scavengers in barrier dispersion
  coatings.

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Oxygen scavenging and aroma affecting enzymes
embedded in barrier coatings
Thank you for your attention