Due to modern environmental packaging requirements the question of recyclability of post-consumer PET-recyclate into new food packaging applications is of increasing interest. In consequence the recycling process and the qualtity assurance of the PET-recyclate must satisfy special requirements. The Fraunhofer-Institute has developed so-called "Challenge-Tests" for the testing of various different recycling processes. These Chanllenge-Tests investigate if a recycler provides a PET-recyclate quality suitable for direct food contact applications. In worst-case scenarios, misuse of PET-beverage bottles such as storage of domestic chemicals and the possible introduction of these compounds into the recycling process is simulated by means of the artificial contamination of post-consumer PET-material with model contaminants. The efficiency of a recycling process can be assessed and optimised with the help of these worst-case scenarios. In addition the requirements for the necessary quality ass urance analysis for PET-recyclate production can also be determined from the results.