510 Novel food packaging techniques manufacture conditions of the package thickness of the functional barrier layer type of functional barrier plastic molecular weight and chemical structure of penetrants(contaminants) concentration and mobility of contaminants in the matrix behind the functional barrier time period between manufacture of package and filling type of foodstuff, i.e. fat content, polarity etc filling conditions and storage(time, temperature)of the packed foodstuffs More scientific background and guidance can be found in the published literature 132,33 as well as in the case studies described below Three-layer PP cups for dairy products In 1994 a study was presented where the safety in food contact use of symmetrically coextruded three-layered polypropylene(PP)cups with recycled post-consumer PP in the core layer(mass fraction 50%)and virgin food grade PP in the adjacent layers was investigated. The recycled PP, which contained about 95% PP and 5%Ps, was completely under source control in the recollection system and had been used in its prior application for packaging yoghurt. The intended application for the recycled material was again packaging milk products such as yoghurt with storage for short times under refrigerated conditions The essential working strategy in this study was to compare the recycled plastic with new, food grade plastic material of the same type. This comparison ncluded experimentally three investigation levels (1)compositional analysis of the raw materials(virgin versus recycled PP pellets) (2)compositional analysis of the finished food contact articles(virgin versus recycled cups) (3) migration testing on both types of cup(virgin and recycled) under regular as well as more severe test conditions After identification and quantification of post-consumer or recycling-related potential migrants on levels(1)and(2)these compounds used as indicator substances to be monitored in migration measurements on level (3) The major post-consumer related compound was identified as limonene,a flavour compound which can be found in many foodstuffs and also in the non- food area. In summary it turned out that none of post-consumer or recycling- related substances could be analytically detected in the food simulants(at a detection limit of 13 ppb) under prescribed migration test conditions However. from the results obtained under more severe test conditions. it could be concluded finally that for the compound with the highest migration, limonene, the migration into a milk product will be below I ppb and for other post-consumer substances far below of I ppb. In conclusion, based on the US• manufacture conditions of the package • thickness of the functional barrier layer • type of functional barrier plastic • molecular weight and chemical structure of penetrants (contaminants) • concentration and mobility of contaminants in the matrix behind the functional barrier • time period between manufacture of package and filling • type of foodstuff, i.e. fat content, polarity etc. • filling conditions and storage (time, temperature) of the packed foodstuffs More scientific background and guidance can be found in the published literature31,32,33 as well as in the case studies described below. Three-layer PP cups for dairy products In 1994 a study was presented34 where the safety in food contact use of symmetrically coextruded three-layered polypropylene (PP) cups with recycled post-consumer PP in the core layer (mass fraction 50%) and virgin food grade PP in the adjacent layers was investigated. The recycled PP, which contained about 95% PP and 5% PS, was completely under source control in the recollection system and had been used in its prior application for packaging yoghurt. The intended application for the recycled material was again packaging milk products such as yoghurt with storage for short times under refrigerated conditions. The essential working strategy in this study was to compare the recycled plastic with new, food grade plastic material of the same type. This comparison included experimentally three investigation levels: (1) compositional analysis of the raw materials (virgin versus recycled PP pellets), (2) compositional analysis of the finished food contact articles (virgin versus recycled cups) (3) migration testing on both types of cup (virgin and recycled) under regular as well as more severe test conditions. After identification and quantification of post-consumer or recycling-related potential migrants on levels (1) and (2) these compounds were used as indicator substances to be monitored in migration measurements on level (3). The major post-consumer related compound was identified as limonene, a flavour compound which can be found in many foodstuffs and also in the non￾food area. In summary it turned out that none of post-consumer or recycling￾related substances could be analytically detected in the food simulants (at a detection limit of 13 ppb) under prescribed migration test conditions. However, from the results obtained under more severe test conditions, it could be concluded finally that for the compound with the highest migration, limonene, the migration into a milk product will be below 1 ppb and for other post-consumer substances far below of 1 ppb. In conclusion, based on the US 510 Novel food packaging techniques