Research project aims to make recycling safer

An EU-funded project is currently being undertaken to establish safer recycling methods for food packaging materials such as PET resins.

Currently the project, which is being undertaken at the Fraunhofer Institut für Verfahrenstechnik und Verpackung​ in Germany, is considering the recycling of a wide range of materials for food purposes, including paper, glass and plastics. But the team says that its research has been limited by the fact that the European legal requirements for materials re-use are not clearly defined.

The major reason for this, the researchers claim, has been the lack of knowledge on additives and contaminants migration from the recycled materials into food, which is prohibited according to current EU Directives. This, they said, is why the food industry has not been willing to accept the use of these materials.

In a previous EU-funded project (contract AIR-CT93-1014), a group of scientists from the Institute focused their research on the migration and recycling of packaging materials. They are now carrying out a project with the aim of documenting the nature and extent of contamination in PET recovered from the food packaging market, and to generate a knowledge base on migration from reused paper and board packaging materials into foods. The scientists will also investigate the use of the so-called Functional Barriers between the recycled material and the food.

Currently PET is an excellent material for food with a low diffusivity and is the most promising polymer for recycling. It is mostly used for bottles and cups and is conventionally recycled by sorting, grinding, washing and drying steps. However, PET for food contact use must be further deep-cleansed by so-called 'super-clean processes' in order to eliminate later transfer of flavour material, for instance.

The project group analysed 900 samples from European PET recyclers. By far the greatest portion of contaminants found in conventionally reprocessed PET were soft drink flavour components originating from the first bottle use. These foodstuff components were typically found in post-consumer PET samples in minute amounts (in the low ppm range). Besides that, a few low molecular weight components were found at very low levels as PET unspecific compounds in trace amounts (lower than 0.5 ppm). Super-clean processed PET, however, was found to be indistinguishable from virgin food grade PET.

In order to investigate the migration behaviour of paper and board (P&B) packaging materials, experimental studies were run using 12 model contaminants and 15 P&B samples. The results of those studies, including the total and specific migration into the foods or food simulants, are to be published shortly. The final report is also to include experiments and new knowledge of the effects of Functional Barriers.