Meat, cheese, fruit and vegetables are often packaged in plastic materials in supermarkets. This means they are in a protective gas atmosphere in which germs have difficulty multiplying and the food lasts longer. In order to maintain this atmosphere for a long time, the packaging materials need gas barriers - which bio-based plastics do not yet have. Researchers from the Fraunhofer Institute for Process Engineering and Packaging (IVV) and the Albstadt-Sigmaringen University of Applied Sciences have therefore been working on this in the joint project PLA4MAP.

Polylactides, soya protein and sunflower wax

In order to fulfil the requirements of the gas barriers, the researchers have developed a composite material consisting of four layers: two top layers made of polylactide (PLA), a protein layer made of soya protein concentrate and a wax layer made of sunflower seed wax, a by-product of edible oil production.

PLA is a biodegradable plastic as it is made from renewable raw materials such as corn starch or sugar cane. Its share in the developed material is just under 82%. PLA could be recycled if suitable and established sorting and recycling streams for this material existed. Less than one per cent of the PLA in plastic food packaging is recycled in Germany.

Significant potential for optimisation

In addition to the lack of recycling infrastructure for PLA, further adjustments need to be made for practical implementation: The production of the bio-based plastic is energy-intensive and its processing has so far only taken place on a pilot scale. According to the Institute for Energy and Environmental Research (ifeu), significant optimisation is still required for widespread use. For example, the current high manufacturing costs could be reduced by expanding global PLA production and, in particular, by reducing the weight of the packaging.

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