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

Abstract

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.

Migration Testing of Polyethylene Terephthalate: Comparison of Regulated Test Conditions with Migration into Real Food at the End of Shelf Life

“…Furthermore, an increase in migration was observed with the increasing ethanol content of the food simulant. This can be explained by the known swelling effect of ethanolic solutions on PET . The results found in this study are in compliance with migration results recently published for 2‐aminobanzamide .…”

“…This can be explained by the known swelling effect of ethanolic solutions on PET . The results found in this study are in compliance with migration results recently published for 2‐aminobanzamide . The value determined with the rapid extraction conditions of 24 h at 50°C according to DIN 1186–15 using 95% ethanol was higher than the value found in the same simulant after 10 days at 40°C and also higher than the values after 10 days at 60°C using the non‐swelling food simulants 3% acetic acid and 10% ethanol.…”

“…The migration values under the test conditions 10 days at 40°C in the food simulants 3% acetic acid and 10% ethanol approximately agree with the predicted values at the end of shelf life, whereas the simulants with higher ethanol contents also overestimate the migration. This agrees closely with the results of a previous study which showed that 20% ethanol causes PET to swell, thus accelerating migration, but also revealed that swelling was temperature dependent . The migration values under the test conditions 10 days at 40°C in the food simulants 3% acetic acid and 10% ethanol also approximately agree with the predicted values after 10 days at 40°C.…”

“…The migration value in iso ‐octane was within the same concentration range as the calculated value, whereas the other screening test conditions using 95% ethanol for 24 h at 50°C and 60°C also yielded overestimates, which is the intention of screening approaches. These overestimates are due to the applied high temperatures as well as to the swelling effect of highly concentrated ethanolic solutions like 95% ethanol . The migration values under the test conditions 10 days at 40°C in the food simulants 3% acetic acid and 10% ethanol approximately agree with the predicted values at the end of shelf life, whereas the simulants with higher ethanol contents also overestimate the migration.…”

“…The migration of 2‐aminobenzamide at the end of shelf life was calculated by mathematical migration modelling for a real application storage time of 365 days at 23°C. The diffusion coefficients at 23°C (4.2 10 −16 cm 2 /s) and 40°C (4.2 10 −15 cm 2 /s) are given in the literature . Both values were determined from migration kinetics into water.…”