Issue 05/2015

Barrier
Barrier… but also bio-based
and thermoformable!
Like its precursor Wheylayer ® , the barrier biomaterial
featured in a past issue of this publication [1], ThermoWhey
is a barrier coating based on whey protein.
As a by-product of cheese manufacturing, whey is available
in abundance, which means there is no direct competition
with food resources. Wheylayer [2] offers an excellent
barrier against oxygen. Although it has the potential to
replace current synthetic barrier layers, such as ethylene
vinyl alcohol copolymers – EVOH – used in food packaging,
it is mainly aimed at plastic laminates (e. g. pouches,
tubes, lids, etc.). While it is able to be thermoformed, as
demonstrated by the production of blisters, this is limited
to a small stretch ratio unless performed right after the
coating application. Indeed, upon storage, the flexibility
and thermoformability of the coating decreases due to the
formation of different new intermolecular interactions in
the protein network [3].
Thermoforming is one of the dominant and growing
technologies in the packaging market. However, the
limited thermoformability of Wheylayer may well have
stood in the way of certain applications, such as trays,
for which there is an actual need. Indeed, despite having
existed on the market for years, bio-based trays do not
meet the barrier properties required for sensitive food
products (e.g. for products packed in modified atmosphere
– MAP). Therefore, selected partners from Spain (IRIS,
Serviplast) and Germany (Fraunhofer IVV, MLANG), who
had participated in the previous project, decided to work
together with a tooling company (GEBA) to improve the long
term thermoformability of whey protein-coated packaging,
with an ultimate goal the production of jars, cups, etc. To
this end, during the first year of the Thermowhey project
[4], the researchers performed different modifications of
the whey proteins and adjusted the coating formulation
to obtain materials with a more thermoplastic-like
behavior, i. e. displaying both stable processability and
barrier properties versus storage time. After this had
been successfully carried out, different deep trays were
produced under optimized processing conditions from
polyethylene terephthalate (PET) and polystyrene (PS) to
which the Thermowhey coating was applied. Further tests
will be performed on bioplastic substrates. Over the next
year, the production of the material will be industrialized
by the participating SMEs and resulting packaging will
also be validated in contact with selected food products.
The ThermoWhey project is expected to have a very
positive impact on the environment, as it solves multiple
challenges: finding a new commercial use for a cheese byproduct
that is currently discarded, replacing petroleumbased
plastics with natural biopolymers that allow
packaging recycling or composting while safeguarding
their performance.
The author wishes to acknowledge the European
Community‘s Seventh Framework Programme for
Research, technological development and demonstration
for co-funding the Thermowhey project under the Manunet
programme through the Catalan Agency ACCIÓ (grant
agreement RDNET 13-3-005) and the Federal Ministry of
Education and Research of Germany (managed by the KIT
Project Management Agency Karlsruhe).
www.thermowhey.eu
References:
[1] E. Bugnicourt, M. Schmid, “Films with excellent barrier properties”,
bioplastics MAGAZINE; Vol. 8, p44; 2013.
[2] For more info, see www.wheylayer.eu
[3] M. Schmid, K. Reichert, F. Hammann, A. Stäbler; Storage timedependent
alteration of molecular interaction - property relationships
of whey protein isolate-based films and coatings; Journal of materials
science, 50(12), June 2015, pp. 4396 – 4404
[4] For more info, see www.thermowhey.eu
By:
Elodie Bugnicourt
Group Leader EcoMaterials
Innovació i Recerca Industrial i Sostenible (IRIS)
Castelldefels, Spain
36 bioplastics MAGAZINE [05/15] Vol. 10