Assessment of Volatile Compounds Released from Conventional Materials Used for Packaging Beverages

The research observed migrated volatiles, differentiated their origins as primary (manufacturing residues) or secondary (degradation during storage), and evaluates their multifaceted impacts. This study employed a controlled experimental design in which 100 mL samples of UHT skimmed milk and fresh whole cow’s milk were aseptically packaged in pre-cleaned PET bottles, pasteurised at 70 °C for 20 minutes, and stored at 4 °C for 35 days.

Duplicate samples were analysed at seven-day intervals (days 0, 7, 14, 21, 28, 35) using headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry (HSSPME-GC-MS) on a DVB/CAR/PDMS fibre. A total of 404 distinct volatile organic compounds (VOCs) were identified in UHT skimmed milk and 261 in fresh whole milk, with aliphatic hydrocarbons dominating both profiles (≈53 %), followed by oxygenated compounds (≈29–31 %).

In skimmed milk, 2-heptanone was the most abundant and consistently detected compound (mean Area % = 21.59; present in all 12 analyses), accompanied by primary migrants such as the phthalate ester DEHP, whereas whole milk exhibited lower diversity and intensity due to fat-mediated sequestration of lipophilic volatiles. Origin classification indicated approximately 60 % primary (PET-derived) volatiles in skimmed milk compared with a balanced 50:50 primary to-secondary ratio in whole milk.

Principal component analysis revealed clear temporal separation between control and PET-exposed samples, with PC1 explaining 42.1 % of variance in skimmed milk and 51.3 % in whole milk. Two-way ANOVA identified storage duration as the strongest predictor of migration (R² = 0.610, p < 0.001), followed by milk type and their interaction (R² = 0.659), while regression modelling showed migration levels increased by approximately 0.58 units per additional storage day (β = 0.62, p < 0.001).

Sensory risk was markedly higher in UHT skimmed milk, where elevated methyl ketones (2-heptanone, 2-nonanone) and aldehydes (nonanal, heptanal) produced intensifying rancid, musty, and cardboard-like off-flavours; safety concerns arose from the presence of phthalates and numerous non-intentionally added substances (NIAS), although most concentrations remained below current specific migration limits; shelf-life stability was more compromised in skimmed milk, as progressive VOC accumulation served as an early indicator of lipid oxidation and quality deterioration.

Overall, measurable VOC migration from PET packaging occurs under realistic refrigerated conditions and is significantly amplified in low fat milk matrices.</p>