Assessing artificial contamination of polyolefins for challenge tests of recycling technologies for Food Contact Applications

Increasing the recycling content in packaging requires novel technologies assessed by authorities, such as the European Food Safety Authority, which requests decontamination efficiency data from challenge tests. To conduct these challenge tests, artificially contaminated input-materials are required. This study examined solid and melt contamination methods and assessed the effectiveness of incorporating surrogates into polyolefins, specifically polypropylene. For solid contamination, polypropylene granules were mixed with surrogates for 14 d at various temperatures. For melt contamination, surrogates were dispensed in polypropylene, polyethylene, and polyethylene terephthalate during the compounding process. Additionally, melt contamination with a tenfold higher surrogate concentration was conducted to compare the contamination behaviours. The concentrations of the surrogates in the matrix materials were determined using gas chromatographic analysis. The results indicate that solid contamination achieves higher surrogate concentrations than melt contamination, but it is time-consuming and challenging to handle on an industrial scale. These findings suggest that both methods can achieve the recommended minimum concentration of 250 mg/kg surrogates with appropriate adjustments and specific recipes of surrogate mixtures for each material. Moreover, this study highlights the need to standardise contamination methods to ensure reliable challenge test results for recycling technologies, ultimately protecting consumers.