Chocopack: Bio-Based Barrier Coating for Sustainable Chocolate Packaging

Project Title

Chocopack – Derivation of sustainable packaging solution for qualitative preservation of oxidation-sensitive chocolates

Challenge

Paper-based packaging has become increasingly popular as a sustainable alternative to plastic. However, for food products that are highly sensitive to oxygen, most paper-based solutions rely on multilayer plastic coatings. These are difficult to recycle, non-biodegradable, and non-compliant with new EU regulations such as the Packaging and Packaging Waste Regulation (PPWR). While some bio-based oxygen barrier coatings are on the market, they are typically sensitive to water and require an additional protective layer, complicating the packaging and recycling process.

Project Approach

The CORNET project Chocopack set out to develop a fully bio-based, single-layer oxygen barrier coating that is also resistant to water. The approach involved modifying cellulose nanofibers (CNF) with both positive (quaternary ammonium) and negative (carboxylate) functional groups. When mixed, these oppositely charged polymers form polyelectrolyte complexes, creating ionic crosslinking bonds that reduce swelling in contact with water. This process is cost-effective, scalable, and avoids the need for synthetic chemicals.

The project was conducted by Celabor (Belgium) in close collaboration with Fraunhofer IVV (Germany), which evaluated the packaging’s effectiveness in preserving oxidation-sensitive chocolate under realistic conditions.

Results & Benefits for Industry

Four different material combinations were tested:

1. Positive CNF with negative CNF
2. Positive CNF with alginate
3. Negative CNF with chitosan
4. Positive CNF with layered silicate (clay)

The combination of positive CNF and clay yielded the most promising results. It achieved an oxygen transmission rate below 0.5 cc/m²·day at 23  °C and 50 % relative humidity in a single coating layer – while also maintaining low sensitivity to water. Although the industrial coating process still requires optimization, the concept has strong potential for application for packaging SMEs.

Food producers will ultimately benefit from this technology by offering more sustainable packaging that meets regulatory requirements and consumer expectations for environmentally friendly products.

Added Value through CORNET

The collaboration between Celabor and Fraunhofer IVV enabled a strong combination of materials development and application testing. The project partners complemented each other’s expertise and benefitted from CORNET’s international, SME-focused funding framework. The consortium also established new ties with Fraunhofer UMSICHT, leading to follow-up research on biopolyesters.

Through CORNET, the partners gained valuable insights into the needs of European SMEs and built a strong foundation for future collaborative innovation.

Impact and Future Outlook

The project successfully demonstrated that high-performance oxygen barrier properties and water resistance can be achieved in a 100 % bio-based, single-layer coating. While the current process is not yet ready for industrial rollout, an ongoing CORNET project (FUNBIOMAT) is working to optimize the coating method and adapt it for larger-scale use. This could soon enable broader application of the technology by packaging and food SMEs.