C-phycocyanin as a functional additive to modulate the structural, antioxidant, and antibacterial properties of chitosan-based films for active food packaging

This study developed films for bioactive packaging based on chitosan (Ch) or chitosan and glycerol (ChG) incorporated with C-PC at 1–8%. Ch4 and Ch8 shifts the thermal degradation of chitosan from 257.9 °C to 266.3 °C, demonstrating that the C-PC strengthens the polymer network and enhances thermal stability of the films. Ch4 and Ch8 had the highest tensile strain (σ u ), (28.3 ± 0.2; 27.4 ± 4.3) and ChG4 and ChG8 had lower values (2.4 ± 0.2; 1.7 ± 0.1). The Young's modulus of Ch4 and Ch8 were (28.3 ± 0.2; 27.4 ± 6.5), whereas ChG4 and ChG8 were (0.1 ± 0.0 for both), Ch samples had superior tensile strength compared to plasticized films, and C-PC has led to decreased stiffness. Color remained stable under visible light but degraded rapidly under UV, although the polymer matrix was preserved, and C-PC acted as an effective light barrier. Ch films had a weaker water barrier, being more indicated for fruit and vegetable packaging due to the greater breathability required by this foodstuff, whereas ChG are more convenient for packaging dried foods. Ch8 had the strongest antioxidant activity (18.82 ± 1.06 for ORAC and 483.83 ± 2.30 for ABTS, μmol of TE/g of sample) and antibacterial activity against Staphylococcus aureus and Escherichia coli (89.78 and 95.71% of inactivation, respectively), whereas ChG8 presented 42.5 and 31.81%, respectively. All films were biocompatible, maintaining >75% cell viability in 7 days. Thereby, Ch films containing C-PC demonstrated strong potential as innovative, active, and bio-based food packaging. • C-PC improved film flexibility, strength, and reduced roughness; • C-PC improved films' opacity and acted as a natural UV-light barrier; • Chitosan films were more thermally stable, and C-PC (4–8%) improved this parameter; • Chitosan and C-PC at 8% had the highest antioxidant and antibacterial activities; • Chitosan and C-PC at 8% exhibited the best bioactive compound release after 48 h.