Less plastic waste thanks to bioactive paper coating for food packaging
Food packaging is a major contributor to the vast amounts of plastic waste that is increasing every year. Whether cold cuts, cheese, meat, fish or even fruit, salads and vegetables, everything is hygienically packed in plastic. In Germany alone, plastic waste from such packaging has accumulated up to 38.5 kilograms in 2017 per inhabitant. That is why researchers from the Fraunhofer Institute for Process and Packaging Engineering IVV and the Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB in Germany have developed an innovative and environmentally friendly coating. environment. It is composed of vegetable proteins and waxes for paper packaging as part of the BioActiveMaterials project. Not only does it save plastic, but it also extends the shelf life of food and can be easily thrown into the recycling container.
Longer shelf life made possible by proteins, waxes and antioxidants
The basis of the new type of sealable bag or wrapping paper is normal paper. It has a special coating of proteins and waxes with bio-based additives. The “special formulation of a long-term stable coating” fulfills several functions at once, emphasizes Dr. Michaela Müller, Head of the Functional Surfaces and Materials Innovation Area at Fraunhofer IGB. “On the one hand, the proteins serve as an oxygen barrier layer and the waxes act as a water vapor barrier, so that fruits, for example, do not dry out so quickly. On the other hand, bio-based additives confer antioxidant and antimicrobial effects,” she explains. “Meat and fish then don’t spoil as quickly.” Overall, the shelf life of food is significantly extended. At the same time, the proteins in the coating ensure that no mineral oil is transferred from the paper to the food, which is necessary because there are still residues of printing ink containing mineral oil in waste paper .
“Our paper-based packaging is also suitable for foods that need to be refrigerated, such as meat. Here, the protective function against oxygen is retained,” adds Müller. Even frozen food could be packed in it. “After use, the packaging goes into the recycling bin; the coating is biodegradable and does not interfere with paper recycling,” says Dr. Cornelia Stramm, Head of Department at the Fraunhofer Institute for Process Engineering and Packaging IVV.
Fraunhofer IVV researchers have already tested the practicality of the coating. “For example, we tested the effectiveness of a particular coating in protecting food from external influences such as water vapour, oxygen and mineral oil,” explains Stramm. The team also applied the coating to the papers using a roll-to-roll process. This involves applying the coating in the form of an aqueous dispersion using a machine on which the paper is guided on rollers.
The magic lies in the mixing ratio
The raw materials for BioActiveMaterials come from natural substances approved for use in foodstuffs. To identify them, the researchers experimented with rapeseed, lupine, whey or sunflower, for example. In this way, unused residues from agricultural production could also be utilized. Waxes, on the other hand, are either beeswax or come from the candelilla bush found in northern Mexico and the Brazilian carnauba palm. “We chose these waxes because they are biodegradable, approved for food use and readily available on the market,” says Müller.
Finally, to produce the proper coating, all ingredients are ground, heated, stirred and mixed using standard laboratory techniques. “The skill lies in the mixing ratio and the order in which you add the individual substances,” says Müller. “The flexibility of the ratio when mixing the different substances also allows us to optimize the coating for specific applications.” A wrap for meat, for example, could be made particularly antimicrobial and antioxidant by adding more antioxidants, while a bag for lettuce could be given a wax coating that provides particularly good protection against dehydration.
Coat food directly
But the bioactive coating would not only be suitable for paper, explain the researchers; cardboard could also be coated with it. Printing the manufacturer’s logo or food law information about the ingredients on the packaging would also be no problem.
Fraunhofer scientists are also currently experimenting with applying the coating directly to foods such as fruits or vegetables to increase their shelf life. From a health point of view, the edible coating is in any case harmless.
Cover picture: A sealed paper bag with the liner inside. After use, the packaging containing the bioactive materials ends up in the recycling bin. © Fraunhofer
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