Polymers from fruit waste provide biodegradable packaging materials
One answer to plastics in packaging is biodegradable materials, which have been on the market for many years and have seen their market share continue to grow. But there are severe restrictions preventing their wider application in food packaging, as these materials do not provide a sufficient barrier against water vapour, oxygen or flavours. The EU-funded HyperBioCoat project addressed this challenge by developing and testing new biodegradable hybrid organic-inorganic coatings for use in food, cosmetics and medical device packaging. “We developed a coating material based on biopolymers extracted from lignocellulosic biomass by combining them with the material class of bioORMOCER®s,” says project coordinator Stefan Hanstein from Fraunhofer IWKS. The bioORMOCER® coatings are bio-based, biodegradable coatings developed by the Fraunhofer Institute for Silicate Research.
Biopolymers from apple residues
Consortium members investigated biodegradable barrier coatings for plastic packaging materials in which the biopolymers are derived from fibrous fruit residues (lignocellulose). According to Hanstein: “One of the project’s greatest challenges involved finding the correct fruit residue for the extraction of lignocellulose and the modification of the hemicellulose to create the desired properties.” Depectinised apple pomace (the main solid waste generated in factories producing cider and apple juice) performed well as a raw material. “The process developed is a combination of extraction and partial hydrolysis (intensified extraction). It provides 1 kg of carbohydrate polymer from 25 kg of dry pomace, with the potential for doubling the yield,” Hanstein explains. Researchers also investigated possible industrial applications for other types of fruit residues, like berry pomace and cocoa shells for novel food production systems and the biotech industry. They demonstrated a route for the chemical modification of carbohydrate polymers that achieves the required compatibility with the lacquer. “This showed how the new bio-based and biodegradable polymer coating can be easily applied and at industrial scale, paves the way for further application in the industry,” comments Hanstein. The next step was to adapt the barrier coating to the different carrier materials, which involves flexible and rigid biopolymer substrates and testing for the packaging applications. According to Hanstein: “This approach improves the properties of packaging materials and of bio-based recyclable materials by using a biodegradable barrier coating.”
Reduced environmental impacts
Cosmetic-bottles production based on fibre-enforced wax was taken to the industrial level by making the material compatible with injection moulding. Hanstein notes: “Project partner Stefanski Design has begun using a slush casting, hand-crafted manufacturing approach producing prototypes for a leading luxury bio resort in Spain. Within the HYPERBIOCOAT project, the basic material has been further developed and is now compatible with large scale injection moulding production.” Project partners also demonstrated a new lean biomass extraction facility which can be installed in small agrobiorefineries. The facility covers a range of applications from providing tailored feedstock for fermentation processes (for example, biogas) and for novel food production systems, like insect culture, to delivering herbal extracts with bioactive compounds such as natural antimicrobials. HYPERBIOCOAT benefits the environment due to its lower CO2 footprint and conservation of natural resources: The supply chain does not require additional plant cultivation areas or additional supplies of water, fertiliser and pesticides. Furthermore, the food processing industry will benefit from a new value chain for their fibrous resources. “The advantage of these residues is that they are not competing with animal feed or food production, and provide an abundant feedstock for compostable as well as recyclable plastic packaging materials,” notes Hanstein. The HYPERBIOCOAT project received funding from the Bio-based Industries Joint Undertaking, a public-private partnership between the EU and industry.
Keywords
HYPERBIOCOAT, packaging, polymer, biodegradable, lignocellulose, hemicellulose, CO2 footprint
