Active 3D-Printed PETG bottles functionalized with olive leaf-derived powders for enhanced olive oil preservation

Bottles (∼180 mL) were produced by three-dimensional (3D) printing using food-grade glycol-modified poly (ethylene terephthalate) (PETG) as an alternative packaging for olive oil. Internal surfaces were functionalized with polydimethylsiloxane (PDMS) coatings containing either freeze-dried powder or freeze-dried aqueous extract powder from cv. ‘Cobrançosa’ olive leaf (0.92 ± 0.10 and 0.80 ± 0.13 mg GAE/mL PDMS , respectively), aiming to reduce oil oxidation while promoting olive leaf valorization. Functionalized bottles were compared with non-functionalized 3D-printed and conventional glass bottles. Olive oil quality was evaluated before and after accelerated storage (30 days, 40 °C, dark) using free acidity, peroxide value (PV), UV extinction coefficients (K 232 , K 268 ), total phenolics, antioxidant activity, oxidative stability (OS), and sensory analysis. All samples suffered oxidation and quality downgrade from extra virgin to lampante (K 232 > 2.60). However, oils stored under accelerated conditions in functionalized bottles showed significantly (P-value < 0.05) lower PV and K 268 , higher OS, better phenolic retention and lower rancidity (3.0–3.1 vs. 4.3) than glass-stored oils. Overall, functionalized bottles provided the greatest protection against oil sensory degradation, followed by non-functionalized and conventional glass bottles. This suggests that PETG/PDMS material itself exhibits a protective effect, enhanced by functionalization, although this empirical interpretation requires mechanistic confirmation. Unsupervised and supervised multivariate analysis confirmed the active packaging protective effect, with oils in functionalized bottles clustering closer to unstored samples. Both coatings were effective, though freeze-dried olive leaf powder being less technically-demanding is more practical. Thus, functionalized 3D-printed bottles emerge as a sustainable and active solution to reduce olive oil oxidation and support by-product valorization.