Food packaging characterization, composition profiles and in vitro testing of micro(bio)plastics from selected...

Plastic food packaging represents a significant source of microplastics (MPs) in food and the environment, posing risks to humans and ecosystems. Replacing single-use plastics with sustainable food packaging (e.g. from renewable biomass) is essential to reduce MPs exposure, although risk assessment studies are still needed. On the other hand, food packaging often labelled as bio-based or biodegradable may contain synthetic polymers that can mislead consumers. This study investigated the composition of e-commerce food contact items (both petroleum-derived and plant-based), and the cytotoxicity of micro(bio)plastics obtained from them by cryo-milling in in vitro assays using Caco-2 cells. Fourier transform infrared analysis identified greenwashing and non-compliance with the EU regulatory framework in certain food packages whose main composition was polypropylene (PP) containing plant fiber additives. Furthermore, in vitro assays showed that none of the MPs tested (50-100 μm, doses 1 mg/mL) caused acute toxicity in Caco-2 cells, although some of the PP-MPs induced cellular stress (up to 25 %), while plant-based microbioplastics (MBs) reduced reactive oxygen species (ROS) levels (by 20-25 %). Particularly valuable results were derived from palm leaf (PL)-MBs where doses above 1 mg/mL induced ROS scavenging and potential cytoprotective effect in Caco-2 cells subjected to oxidative stress. This can largely be attributed to the presence of (poly)phenols (448 ± 25 μg/g) (mainly flavonols and hydroxycinnamic acids, 110 ± 7 and 297 ± 15 μg/g, respectively) in PL-MBs, which are natural antioxidants, highlighting the potential benefits of this type of active packaging for the food industry and human health.