The consortium developed a value chain in which branched carbohydrate building blocks extracted from fruit residues were tailored to meet the requirements of hybrid (inorganic-organic) barrier coatings on flexible films and rigid containers, trays or blisters.
1 Extraction
Partners from the food processing industry provided various fruit residues. Depectinized apple pomace proved to be a well-performing raw material for the pilot-scale extraction of a branched sugar structure. The process developed by Fraunhofer IWKS is a combination of extraction and partial hydrolysis (intensified extraction). It provides 1 kg carbohydrate polymer from 25 kg dry pomace, with the potential for doubling the yield with instrumental upgrades.
2 Modification
Chemical modification is essential for achieving the compatibility with the lacquer. Fraunhofer ISC demonstrated a route for chemical modification of carbohydrate polymers, which achieves the required compatibility. For the apple pomace carbohydrate, Fraunhofer IWKS has developed a one-step, chemical modification procedure that can be scaled up to an industrial level. The project created valuable information about possible industrial applications for other types of fruit residues: berry pomace and cocoa shells, e.g. for novel, food production systems and for the biotech industry.
3 Application
Coatings on three-dimensional mass products are particularly demanding in terms of a cost-efficient technological process, which achieves a coating with uniform thickness. The HyperBioCoat partner from Spain, AITIIP, elaborated a robotic spraying technology for ORMOCER® lacquers. AITIIP is a research organisation dedicated to (bio) plastic engineering, with pilot-scale facilities for thermoforming and injection moulding, including facilities for foaming with supercritical fluids (SCF). In the HyperBioCoat project, AITIIP has produced several demonstrators for trays, blisters and bottles based on PLA and fibre-enforced wax and improved the robotic spraying process. Processes and conditions have been optimized for the selected materials. The HyperBioCoat partner from Croatia, MiPlast, produced various bio-based films and optimised printing technology for the coating.
The main results for the assessment of the overall compostability are that developed bioORMOCER®, flexible packaging (biodegradable film + developed bioORMOCER®) and rigid packaging (trays+ developed bioORMOCER®) are fully compostable in terms of biodegradation, disintegration and ecotoxicity compliance with EN 13432 requirements. Regarding the total migration of the HYPERBIOCOAT flexible and rigid packaging, the tests were performed according to the European Regulation EC N. 10/2011 to verify the compliance with the Overall Migration Limit of 10 mg/dm2 in several simulants and with different experimental conditions, in terms of time of contact and exposure temperature. The coating with bioORMOCER® complies with the migration limit at 60°C for 10 days with all tested simulants. Accordingly, the packaging can be applied for food packaging application for contact times above 30 days at room temperature as real use.