Hydrocolloid-based coatings applied on biobased/biodegradable food flexible packaging, A review. Part 1 - Biopolymer to coat and available technologies

The shift towards sustainable food packaging has intensified research into hydrocolloid-based coatings applied to biobased and biodegradable flexible films. Indeed, most of the biobased and/or biodegradable film available for the food market exhibits too low properties, but that could be compensated by coating applications. This review explores the potential of hydrocolloids as coating materials to improve the functional properties of sustainable flexible packaging such as polylactides, polyhydroxyalkanoates, thermoplastic starch, polycaprolactone. Hydrocolloid-based coatings, including proteins, polysaccharides, and their composites, are particularly promising due to their ability to improve barrier, surface and mechanical performance while maintaining biodegradability and food safety. The choice of technique for coating application depends on the desired coating thickness, adhesion strength, and functional enhancements. Various coating technologies are discussed, ranging from solvent-free (dry) processes, such as extrusion-lamination and hot press techniques, to wet-based (solvent) methods, including solution casting, spray coating, electrospinning, etc. Surface treatments, such as plasma activation, are often required before coating application to enhance adhesion, wettability, and mechanical resistance. This review provides an in-depth analysis of available biodegradable polymer films suitable for coating and food applications and the coating technologies, setting the foundation for the development of next-generation eco-friendly packaging films.

For all partners, this work was supported by the EVOLVEPACK project, a PRIMA-Horizon 2020. For the University of Zagreb (authors Kurek, Ščetar, Galić), the EVOLVEPACK Grant is PCI2024-153409, work is also supported by the Croatian Ministry of Science, Education and Youth. For the IATA (author Fabra), the EVOLVEPACK Grant is Grant PCI2024-153409, funded by MICIU/AEI/10.13039/501100011033 and, by ERDF A way of making Europe. The Accreditation asCenter of Excellence Severo Ochoa CEX2021-001189-S funded by MCIU/AEI/10.13039/501100011033 is also fully acknowledged. For the university of Burgundy Europe (authors Debeaufort, Benbettaieb and Ghasemi), the EVOLVEPACK grant is PCI2024-153409 and is also funded by the National Agency for research (ANR), referenced ANR-24-P013-0008-04, and contributes also to NanoBap project grant n° ANR-23-CE09-0003-02.

With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2021-001189-S)

Peer reviewed