Chemical migration, digestive behaviors and effect on gut microbiota of PLA and PBAT oligomers

As biodegradable food contact materials (FCMs), polylactic acid (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) may release oligomers into food and raise potential health concerns. This study investigated the migration characteristics and digestive behaviors of oligomers by combining migration experiments, an in vitro digestion model, and high-resolution mass spectrometry. Moreover, the effects of the migrants from both materials on gut microbiota were evaluated following in vitro colonic fermentation for 48 h. The results indicated that 51 PLA oligomers and 45 PBAT oligomers were released into food simulants, with the migration increasing with ethanol concentration. Cyclic oligomers exhibited higher migration than linear oligomers. During digestion, PLA oligomers were almost completely degraded, whereas PBAT oligomers increased, additionally, cyclic oligomers were more susceptible to degradation. Migrants from both materials exhibited cytotoxicity effect on Caco-2 cells, disrupted the gut microbiota homeostasis, affecting multiple metabolic pathways. Especially, the migrants from PBAT inhibited the production of acetic, butyric, and isobutyric acids, while reducing the degradation of propionic acid. Overall, PBAT may pose a greater hazard than PLA. In conclusion, based on a new perspective of "lifecycle", this systematic study will contribute to a deeper understanding of the safety of PLA and PBAT when utilized as FCMs.