Upcycling of post-consumer PLA into active packaging films: Structural and functional assessment of rPLA/PCL blends with quercetin

The detrimental impact on the environment derived from the wrong management of conventional plastics is promoting the use of biobased and biodegradable materials for food packaging. Specifically, poly(lactic acid) (PLA) is characterized by its compostability, availability and its easy processing by melt extrusion, becoming one of the most used biopolymers in the industry. Because PLA is a valuable polyester, its recyclability should be considered as an alternative to compostability. In this work, the post-consumer recycled PLA (rPLA) obtained after simulating the service life and recycling processes of commercial PLA-based water bottles was used to develop new active packaging systems. Polycaprolactone (PCL), a polyester known for its excellent deformability, was added to mitigate the deterioration of rPLA during its reprocessing and afford different characteristics. Likewise, the addition of quercetin (Q), a natural polyphenolic antioxidant, can increase the interaction between both polymers and allow a greater preservation of food sensitive to oxidation through its progressive release. In this work, active films based on rPLA and PCL blends at different ratios (85/15 and 70/30) incorporating Q at 3 wt% were melt-extruded. Thermal, optical, diffusional (specific and overall migration) and morphological properties were analyzed, in addition to their antioxidant capacity and Q release profiles. Micrographs showed polymeric blends exhibited spherical-shaped PCL particles surrounded by rPLA matrix, and their characterization indicated the blending with PCL and Q increased rPLA crystallinity. In addition, the release of Q and their antioxidant activity increased with PCL concentration and ethanol content in the food simulant. • Use of post-consumer PLA from water bottles to develop new active packaging systems. • PLA bottles underwent accelerated aging and washing to simulate post-consumer rPLA. • Active films composed by rPLA, PCL and quercetin were produced via melt extrusion. • Quercetin release depended on food simulant and PCL concentration.