Synthesis of biodegradable chitosan film loaded with Pseuderanthemum palatiferum leaf extract obtained by supercritical CO2 extraction: Characterization, antibacterial properties, and fruit preservation

In this study, the supercritical CO₂ technique was used to obtain polyphenol-rich extracts from the Pseuderanthemum palatiferum (P. palatiferum) leaf. The extraction was conducted at 349 bar and 60 °C for 2 h, using ethanol as a co-solvent. The combination of P. palatiferum leaf extract (PPLE) with chitosan (CS) was investigated to fabricate CS-PPLE films by using the solution-casting method. The effects of different concentration of PPLE (1, 2, and 3 % v/v compared to the weight of CS) on the mechanical, biodegradable, antimicrobial, and food preservation properties of films were evaluated. Characterization of the films was performed via scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) techniques, and Fourier transform infrared spectroscopy (FTIR), revealing the intermolecular interactions between chitosan and the bioactive compounds in the extract. The soil burial tests showed that CS−PPLE films have good biodegradability in soil after 21 days. The antibacterial activity of the material also showed the highest inhibition performance towards Escherichia coli. The P. palatiferum loaded films showed good preservation performance for both persimmon (Diospyros kaki) and sugar apple (Annona squamosa), extending their shelf life to 9 and 5 days at room temperature, respectively, compared to the control films, which preserved them for only 7 and 3 days. All results demonstrated their potential for sustainable material and extending shelf life of fruit, which could be used in food packaging.