512 Novel food packaging techniques 40C up to 76 days. From the results it was concluded that HIPs was an appropriate functional barrier under given application parameters which need to be optimised for the particular purpose. Generally, layer thicknesses from 100um to 200um were found to be very efficient, and this even in the case of exaggerated test conditions as applied in this study for fatty contact. When considering aqueous food products and room or cooling temperature applications, this conclusion is still much more valid and of general character Again, as with the PET study, the contamination effect from the core layer to the virgin barrier layers during the high temperatures of the coextrusion process was investigated. For instance, for a 50um thick HIPS layer it turned out that the same contamination effect of the food contact surface with the surrogate toluene, which is obtained after one year's storage at room temperature, is achieved within I second only at the coextrusion temperature of 200C 23.5.2 Direct contact applications Mono-layer PET bottle for soft drink applications As mentioned before. Pet is one of the most favoured candidates for closed- loop recycling. Due to higher costs of manufacturing multi-layer bottles, the bottle manufacturing and recycling companies started the development of recycling processes without a functional barrier of virgin PET. One decade later several super-clean recycling processes were established on an industrial scale In 2002, companies in Europe have built an overall recycling capacity of about 65.000 tons per year of super-clean post-consumer PET which can be used in direct food contact applications. The cleaning efficiencies of all the applied deep-cleansing recycling processes were investigated by challenge tests and the cleaning efficiencies are well known(see for example Lit. 414). In Europe today, the mono-layer direct food contact approach has received clearance for use in Austria, Belgium, France, Germany, The Netherlands, Norway, Sweden and switzerland Mono-layer hDPE bottles for fresh milk In 2002 the following project was started in Northern Ireland. Milk bottles were recovered by a deposit system and were subjected to a bottle-to-bottle recycling process. Due to the recovery system the recycled HDPE was completely under source control and had been used in its prior application only for packaging fresh milk. The recovered material was recycled first by a conventional washing based recycling process and then further deep-cleansed using a super-clean process. Subsequently the recycled material was used with a content of 20 to 30% without a functional barrier. The intended application for the recycled material was again bottles for fresh milk with short time storage under refrigerated conditions The project had several R&d phases before: after a screening of post consumer HDPE milk bottles for compounds which are potential migrants the deep-cleansing process was evaluated and optimised. Subsequently, the40ºC up to 76 days. From the results it was concluded that HIPS was an appropriate functional barrier under given application parameters which need to be optimised for the particular purpose. Generally, layer thicknesses from 100m to 200m were found to be very efficient, and this even in the case of exaggerated test conditions as applied in this study for fatty contact. When considering aqueous food products and room or cooling temperature applications, this conclusion is still much more valid and of general character. Again, as with the PET study, the contamination effect from the core layer to the virgin barrier layers during the high temperatures of the coextrusion process was investigated. For instance, for a 50m thick HIPS layer it turned out that the same contamination effect of the food contact surface with the surrogate toluene, which is obtained after one year’s storage at room temperature, is achieved within 1 second only at the coextrusion temperature of 200ºC. 23.5.2 Direct contact applications Mono-layer PET bottle for soft drink applications As mentioned before, PET is one of the most favoured candidates for closed￾loop recycling. Due to higher costs of manufacturing multi-layer bottles, the bottle manufacturing and recycling companies started the development of recycling processes without a functional barrier of virgin PET. One decade later several super-clean recycling processes were established on an industrial scale.1 In 2002, companies in Europe have built an overall recycling capacity of about 65.000 tons per year of super-clean post-consumer PET which can be used in direct food contact applications. The cleaning efficiencies of all the applied deep-cleansing recycling processes were investigated by challenge tests and the cleaning efficiencies are well known (see for example Lit. 20,21,22). In Europe today, the mono-layer direct food contact approach has received clearance for use in Austria, Belgium, France, Germany, The Netherlands, Norway, Sweden and Switzerland. Mono-layer HDPE bottles for fresh milk In 2002 the following project was started in Northern Ireland.37 Milk bottles were recovered by a deposit system and were subjected to a bottle-to-bottle recycling process. Due to the recovery system the recycled HDPE was completely under source control and had been used in its prior application only for packaging fresh milk. The recovered material was recycled first by a conventional washing based recycling process and then further deep-cleansed using a super-clean process. Subsequently the recycled material was used with a content of 20 to 30% without a functional barrier. The intended application for the recycled material was again bottles for fresh milk with short time storage under refrigerated conditions. The project had several R&D phases before: after a screening of post￾consumer HDPE milk bottles for compounds which are potential migrants the deep-cleansing process was evaluated and optimised. Subsequently, the 512 Novel food packaging techniques