Diffusion behaviour of the acetaldehyde scavenger 2-aminobenzamide in polyethylene terephthalate for beverage bottles

Polyethylene terephthalate (PET) bottles are widely used as packaging material for natural mineral water. However, trace levels of acetaldehyde can migrate into natural mineral water during the shelf life and might influence the taste of the PET bottled water. 2-Aminobenzamide is widely used during PET bottle production as a scavenging agent for acetaldehyde. The aim of this study was the determination of the migration kinetics of 2-aminobenzamide into natural mineral water as well as into 20% ethanol. From the migration kinetics, the diffusion coefficients of 2-aminobenzamide in PET at 23 and 40°C were determined to be 4.2 × 10^{− 16} and 4.2 × 10^{− 15} cm² s^–1, respectively. The diffusion coefficient for 20% ethanol at 40°C was determined to be 7.7 × 10^{− 15} cm² s^–1, which indicates that 20% ethanol is causing swelling of the PET polymer. From a comparison of migration values between 23 and 40°C, acceleration factors of 9.7 when using water as contact medium and 18.1 for 20% ethanol as simulant can be derived for definition of appropriate accelerated test conditions at 40°C. The European Union regulatory acceleration test based on 80 kJ mol^–1 as conservative activation energy overestimates the experimentally determined acceleration rates by a factor of 1.6 and 3.1, respectively.