Incorporation of Limonene Oligomers into Poly(itaconic acid)/Starch Blend Films for Antimicrobial and Antioxidant Packaging Applications

In this study, we devised novel poly­(itaconic acid)/starch (PIA/S)-based films by incorporating both limonene (LIM) and low-molar-mass poly­(limonene) (PL) at varying concentrations (3, 6, and 9/100 g of starch). Our investigation centered on evaluating their antimicrobial and antioxidant capabilities with a focus on characterizing the most promising bioactive film formulations. Surprisingly, LIM-incorporated films showed no discernible bioactivity, contrasting with the remarkable outcomes seen in PL-incorporated films. Specifically, the latter demonstrated effectiveness against several pathogenic microorganisms including Bacillus cereus, Clostridium perfringens, Pseudomonas aeruginosa, and Colletotrichum gloeosporioides. Moreover, these films exhibited notable 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of up to 13.4%, showcasing the hitherto unexplored potential of PL in this domain. This study also highlights the influence of PL incorporation on the general film properties. Overall, the films displayed uniform morphology, reduced tensile strength, and decreased elongation at break, accompanied by an increased moisture content and water solubility. No significant alterations were noted in the water vapor barrier properties. Notably, the introduction of PL also brought about an exceptional ultraviolet (UV)-light barrier effect, raising the prospect of utilizing PIA/S/PL films as innovative active packaging materials in the future.