608 Novel food packaging techniques 10 ppm 5 ppm 3 0.05 ppm 0.Ol ppm 0.001 350 Molecular weight of contaminant Ig/mol l Fig 23. 1 Correlation of migration into food and calculated maximum allowable concentrations(in ppm) of the surrogates in the bottle wall in dependency of the molecular weight for a II Pet bottle in 95% ethanol (10 d at 40C) view of challenge tests and particular focus on surrogates the following very conservative maximum allowable concentrations of surrogates in the bottle wall can be calculated independently of the package thickness: toluene 4.5 ppm, chlorobenzene 5.5 ppm, phenyl cyclohexane 7.5 ppm, benzophenone 8.6 ppm and methyl stearate 17 ppm. These concentrations can be considered to correlate safely with the 10 ppb migration limit for any food or simulant at test conditions of l0 days at40℃C Hot-fill conditions are also covered by the above mentioned modelling data Using test conditions of I h at 70C followed by 10 days at 40oC, which are the usual test conditions for hot-fill testing, instead of only 10 days at 40C the calculated migration rises only insignificantly. Going to a more severe ndition,e.g. 30 min at 100oC followed by 10 d at 40oC the factor is 1, 21 This shows that the migration from PET containers into food simulants (e.g 95% ethanol as a worst case)are very low even under hot-fill conditions 23. 4.5 Sensory Test Requirements luber and Franz investigated the sensory properties of conventionally recycl polymers(HDPE, PP, PS and PET). 4 They found in all samples the polymer specific odour found in virgin polymers. Nevertheless, all of the recycled polymers could be identified due to additional odour notes. For PEt the lowest odour deviation was noticed and an increasing off-odour was perceptible from PS to PP and HDPE. However, the results are not surprising because in all investigated polymer samples flavour compounds like limonene can be found inview of challenge tests and particular focus on surrogates the following very conservative maximum allowable concentrations of surrogates in the bottle wall can be calculated independently of the package thickness: toluene 4.5 ppm, chlorobenzene 5.5 ppm, phenyl cyclohexane 7.5 ppm, benzophenone 8.6 ppm and methyl stearate 17 ppm. These concentrations can be considered to correlate safely with the 10 ppb migration limit for any food or simulant at test conditions of 10 days at 40ºC. Hot-fill conditions are also covered by the above mentioned modelling data. Using test conditions of 1 h at 70ºC followed by 10 days at 40ºC, which are the usual test conditions for hot-fill testing, instead of only 10 days at 40ºC the calculated migration rises only insignificantly. Going to a more severe condition, e.g. 30 min at 100ºC followed by 10 d at 40ºC the factor is 1,21. This shows that the migration from PET containers into food simulants (e.g. 95% ethanol as a worst case) are very low even under hot-fill conditions. 23.4.5 Sensory Test Requirements Huber and Franz investigated the sensory properties of conventionally recycled polymers (HDPE, PP, PS and PET).14 They found in all samples the polymer specific odour found in virgin polymers. Nevertheless, all of the recycled polymers could be identified due to additional odour notes. For PET the lowest odour deviation was noticed and an increasing off-odour was perceptible from PS to PP and HDPE. However, the results are not surprising because in all investigated polymer samples flavour compounds like limonene can be found in Fig. 23.1 Correlation of migration into food and calculated maximum allowable concentrations (in ppm) of the surrogates in the bottle wall in dependency of the molecular weight for a 1 I PET bottle in 95% ethanol (10 d at 40ºC).30 508 Novel food packaging techniques