Migration of di (2-ethylhexyl) adipate plasticizer from PET bottles into acidic food simulant: Determination of diffusion coefficients and activation energy of diffusion

The migration of packaging material constituents into food is a product of the interaction between the food and packaging material. This phenomenon is of importance because some migrating substances may be toxicologically carcinogenic and endanger consumer safety. Gas chromatography was used to determine the migration of di (2-ethylhexyl) adipate (DEHA) into food simulant. Differential scanning calorimetry (DSC) was used to evaluate the effect of an acidic solution on PET structure. The diffusion coefficient of the DEHA plasticizer into the PET bottles was calculated using the Piringer model and the activation energy of diffusion at 45°C was estimated using the Arrhenius relation. It was observed that the migration of DEHA increased over time and temperature. An increase in storage temperature from 25°C to 45°C considerably increased the diffusion coefficient of the migrant in PET. DSC results showed that the glass transition temperature (Tg) of the polymer at a given temperature does not change over time، indicating no change in the polymer structure from contact with the acid solution. The amount of DEHA migration into the acidic food simulant was below the standard limit set by the European Commission for secure PET packaging used for yogurt drinks.