Physicochemical characterization, antioxidant and antimicrobial activities of chitosan film containing Sauropus androgynus extract prepared by solution casting and supercritical impregnation

Abstract

Sauropus androgynus extract (SAE) was incorporated with chitosan to produce solution casting film (SAE-SCF) and supercritical impregnation film (SAE-SIF). The physicochemical characterization and biological activities of SAE-SCF and SAE-SIF films were evaluated and compared. In terms of total phenolic content (TPC) and total flavonoids content (TFC), SAE-SCF (TPC: 49.14–71.88 mg GAE/g; TFC: 32.73–57.05 mg QE/g) obtained higher results than SAE-SIF (TPC: 8.40–18.90 mg GAE/g; TFC: 1.97–12.34 mg QE/g). FTIR results confirmed the interaction between SAE-active compounds and chitosan via hydrogen bonding and electrostatic interaction. Due to the formation of hydrogen bonding or cross-linking effects in SAE-chitosan film, the light opacity (1.748–3.375 AU), water vapor permeability (2.87–3.92 × 10−11 g m−1.s−1.Pa−1), and mechanical properties (tensile strength; 8.65-15.72 MPa; elongation at break: 7.95–13.25%) were enhanced compared to neat chitosan film, with SAE-SCF showing higher performances than SAE-SIF. The antioxidant activities of both films were evaluated using ABTS (IC50: 55.98–97.85 μg/mL) and DPPH assays (IC50: 53.68–143.04 μg/mL), with SAE-SCF showing higher inhibition of free radicals than SAE-SIF. The ferric-reduction power was recorded (28.17–94.95 Trolox μmol/mL), and SAE-SCF achieved a higher reduction power than SAE-SIF. In antimicrobial analysis, SAE-SCF demonstrated the best reduction of viable growth of all tested foodborne microorganisms. Overall, the functional performance of SAE-SCF is better than SAE-SIF in all tested aspects. The results revealed the potential of SAE-SCF to be utilized as a food packaging material.