All the whey - packaging made from dairy products
Markus Schmid, Florian Wild and Karin Agulla, all of the Fraunhofer Institute for Process Engineering and Packaging IVV, Freising, Germany, outline the initial results of a project to produce recyclable and biodegradable packaging from dairy products.
Increasing the life of products using environmentally friendly materials is one of the main goals for packaging companies. At the Fraunhofer Institute for Process Engineering and Packaging IVV, in Germany, researchers have been working on the Wheylayer project since 2008. The aim is to replace polymer layers in packaging films with a biomaterial coating made of whey protein. The idea is that the antimicrobial compounds, which are naturally present in whey, can be used to extend the shelf-lives of foods. Whey is produced during cheese manufacture and is available in large quantities.
Lamination is used to produce customised laminates that meet food packaging requirements. The goal is to replace expensive, non-renewable ethyl vinyl alcohol (EVOH), which is currently used as a barrier material in many food packaging systems.
The role of the Fraunhofer IVV in this collaborative research is to optimise the barrier properties of whey protein films and the active antimicrobial and antioxidative effect of the coating. To do this, pure protein isolates are recovered. The film-forming properties of proteins from sweet and sour whey are being fine tuned through chemical modification and partial enzymatic hydrolysis. The end-materials are whey protein formulations with good barrier properties, adhesion, and mechanical integrity, preventing delamination and brittle fracture. The oxygen barrier properties (OTR) of <2cm3 (STP)/(m2 d bar) and a water vapour barrier (WVTR) of <20g/(m2 d) for a whey layer thickness of 100µm should mean that there is no longer the need to coat conventional packaging substrates with synthetic polymers. This will reduce CO2 emissions and the consumption of resources for packaging production.
The whey protein formulations developed at the Fraunhofer IVV are being coated onto polyethylene terephthalate, polyethylene, and polylactic acid film substrates. This work is carried out on both a laboratory and pilot plant scale. A control coater is being used for the laboratory-scale work, which guarantees a reproducible layer thickness. After coating, the layers are dried byconvection and examined before scaling up process is undertaken. The most promising whey protein formulations are being manufactured on a larger scale and coated onto selected substrates using the lacquering and laminating plant at the Fraunhofer IVV.
Using corona pre-treatment allows the surface energy of the substrate materials to be significantly increased and thus provide good adhesion. The sample materials manufactured were tested for their oxygen and water vapour barrier properties.
Further aims of the project were to improve the recylability of the laminates and to study the biodegradability, compostability, and toxicity. This work is being carried out by the University of Pisa, Italy. Lifecycle assessments were also drawn up for the various formulations in order to establish the effect of raw material and energy usage on performance. Initial studies have shown that it is possible to completely dissolve the barrier coating from the substrate, without leaving any residues. Professor Andrea Lazzeri, from the University of Pisa, Italy, who is leading this work, says this will allow type-pure recycling of laminate materials.
In order to establish that the new packaging systems have no adverse effect on the sensory properties of foods, storage tests are being undertaken at Technologie-Transfer-Zentrum (ttz) Bremerhaven, Germany, with foods such as sausages, cheese, and fish. Jessica Wildner, a ttz researcher, explains, ‘We are carrying out consumer tests to see whether these new packaging systems change the taste and aroma profiles of the contents, and how this is perceived’.
In the meantime, several project goals have been achieved. The Fraunhofer IVV team has successfully manufactured a multilayer packaging film containing a whey protein barrier layer, using a roll-to-roll process. This type of manufacture is a key prerequisite for meeting commercial criteria. Ismael Almazan, Head of the engineering group at IRIS, a Barcelona, Spain, based research institute, says, ‘We are looking forward to scaling up the process that was established by Fraunhofer at the lab and pilot scale level and fully integrating it in an industrial coating system to turn the wheylayer material into a successful technology in the packaging sector.’ The project is scheduled to run until 2011 when funding ends.
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Wheylayer, funded under the EU Seventh Framework Programme, is a joint European project involving 14 partners from seven EU member states. In addition to packaging manufacturers and industrial associations, the project partners include process engineering experts, recycling specialists, research organisations and producers of dairy products.