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Full recyclable food package with enhanced gas barrier properties and new functionalities by the use of high performance coatings

Periodic Reporting for period 2 - REFUCOAT (Full recyclable food package with enhanced gas barrier properties and new functionalities by the use of high performance coatings)

Reporting period: 2018-12-01 to 2020-09-30

- Problem:
Food industry requirements are very high in terms of barrier propierties that so far are only reachable by multilayer, metalised structures not degradable and with complex and constly recycling proceses.

- Importance for society:
Replacing the oil-based packaging materials with bio-based ones might give a competitive advantage due to more sustainable and greener image, maintain properties. RefuCoat project aims to develop hybrid bio-based high oxygen/water barrier and active coatings to be used in a monolayer bio-based packages (films and trays) as alternative to current metallised and modified atmosphere (MAP) packages. Currently, both types of packages are based on the use of non-renewable materials in multilayer structures that lead to complex and expensive recycling steps.

- Overall objectives:
- 1: Microbiological modification of middle chain polyhydroxyalkanoates (PHA) to achieve a polymer with high water barrier.
- 2: Production and purification of glycolic acid (GA) for reactive extrusion polymerization from mono ethylene glycol (MEG) using gold based catalysts.
- 3: Development of polyglycolic acid (PGA) low melting temperature based adhesives to be used in the hybrid coating formulations (Linked to WP3).
- 4: Development of biodegradable Organic–Inorganic Hybrid Coatings based on the combination of modified silica oxide and PGA as a real alternative to metallised coatings.
- 5: Incorporation of an active substance (antimicrobial and antioxidant) to the hybrid coating to enlarge the shelf life of selected foods. Shelf life target increase of selected food products up to 15% .
- 6: To produce new packages based on Bio-PET + hybrid and active coating with high water and oxygen barriers.
- 7: To produce new packages based on Bio-PE + hybrid and active coating with high water and medium oxygen barriers.
- 8: To produce new packages based on PHA middle chain + hybrid and active coating with high water and medium oxygen barriers.
- 9: To demonstrate the safety & regulatory compliance, as well as environmental & economic sustainability of the developed processes and products (linked to WP6).
- 10: To maximize the innovation impacts of the project for contributing to the uptake of the project results for companies’ business and employment growth.
REFUCOAT projects investigates hybrid bio-based high oxygen/water barrier and active coatings to be used in a monolayer bio-based food packages (films and trays) as alternative to current metallized and modified atmosphere (MAP) packages to avoid the use of non-renewable materials in multilayer structures that currently lead to complex and expensive recycling steps.

After development of REFUCOAT project and once the different packages obtained have been characterized and validated, it can be concluded that the package developed for Potato Chips Package from GRUPO APEX is a good alternative to the current one. Barrier properties are comparable as well as the mechanical properties as sealing temperature and friction coefficient. Furthermore, the packaging is compostable while the current structure is hardly recyclable. In the case of breadcrumb package, a workable structure has also been obtained. It presents better barrier properties than the actual one and regarding the mechanical properties, the sealing temperature and the friction coefficient are lower, so this structure represents an improvement in the production speed. As in the potato chips package, the structure obtained is compostable, more sustainable than the current one that is hardly recyclable (PP/PE). Finally, for chicken packaging, the shelf-life has been extended thanks to the active coating developed and the mechanical properties (sealing temperature and friction coefficient) are better than those of the current packaging. Also, business plans for final users was developed in the project, in order to set the ground to futur project results exploitation as soon as they are fully developed.
a) Progress in the field of mcl-PHA
An efficient fermentation process is being developed for the production of modified mcl-PHA. Using starch rich residues from DACSA, different production pathways of selected Pseudomonas and other bacterias strains are exploited, through β-oxidation pathway through the manipulation of genes to obtain higher hydrophobicity in the mcl-PHA. The PHA monomer composition modulation procedure according to a desired final application properties still being a novelty solution for polymer design.
By the other hand the improvement of PHAs properties for packaging can be optimised by blending them with other polymers or additives. In order to increase market feasibility, low cost renewable feedstock such as starch rich residues from DACSA production process will be employed.

b) Progress in the field of hybrid coating
There are a wide range of companies focusing in sol-gel technology for the of production functional coating based on sol-gel approach for different applications. A sol-gel approach for obtaining an inorganic-organic hybrid coating PGA/micro size Si-SiO2 still being a challenge for most biodegradable polymer. REFUCOAT has being able to formulate PGA hybrid coating based on hydrogen bonds.

c) Progress in the field of PGA
Within Refucoat a continuous solvent-free method for PGA polymerization was developed using the polycondensation route. Polycondensation is seen as a possible way to produce PGA in a one-step-synthesis. Using this method compared to solvent-based batch processes not only saves potentially costly and/or hazardous solvents but also ensures minimal process steps and therefore less thermal stress on the product. The processing knowledge about PGA polycondensation can potentially be used for other polycondensation reactions to transfer their synthesis from batch to continuous as well.

d) Progress in the field of PGA hybrid coating
Biodegradable polymers like PGA have a great potential and widely used in biomedical applications due to their biodegradability and biocompatibility, however, limited research based on PGA polymers has been studied for other applications due to insolubility of PGA in most of the solvents and rapid degradation of PGA. A sol-gel approach for obtaining an inorganic-organic hybrid coating PGA/micro size Si-SiO2 still being a challenge for most biodegradable polymer. REFUCOAT has being able to formulate PGA hybrid coating based on hydrogen bonds.

e) Progress in the field of active coating
In this project, there are two very novel approaches on active coating:
• introducing bacteriophages in the packaging technology is proposed, with the expected result of reducing foodborne illness by actively inhibiting target microorganisms providing an additional inactivation process beyond the end of the production process.
• hybrid coating with barrier and active properties by including antioxidant compounds that will be tailored to the application on different substrates and validated for different food products such as potato chips and bread crumbs.
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