Photothermal functionalized antibacterial packaging film with controllable release capability for fruit preservation

The traditional contact release active packaging film is easily restricted by the strict storage environment and designing a more intelligent release system to achieve lasting food preservation is still a challenge. Herein, a light-responsive thermal-controlled curcumin release packaging film was fabricated by integrating chitosan with Cu-MoO_x and curcumin (CS/CMC). The addition of filler did not destroy the crystal structure and thermal stability of the chitosan matrix. CS/CMC film also possessed satisfactory visual identifiability (ΔE* ≥ 14.98), good light transmittance (T₆₆₀ ≥ 79.99 %), enhanced mechanical properties (≥ 48.21 MPa), and excellent barrier performance against ultraviolet light (T₂₈₀ ≤ 29.2 %), and water vapor (≤ 0.74 × 10^-10 g m^-1 s^-1 Pa^-1). Additionally, CS/CMC film obtained superior photothermal performance from Cu-MoO_x and exhibited good photothermal stability. Benefiting from the photothermal activity, CS/CMC film realizes the intelligent and controllable release of curcumin. The released curcumin and photothermal showed synergistic antibacterial ability with an antibacterial rate of 99.33 % for E. coli and 99.23 % for S. aureus based on CS/CMC_0.02 under near infrared (NIR) irradiation. Besides, CS/CMC_0.02 film could also efficiently inhibit P. italicum and P. expansum under NIR irradiation. Tangerine treated with CS/CMC_0.02 + NIR exhibited a longer shelf life and less nutrient loss than polyethylene (PE) film, verifying the good potential of CS/CMC_0.02 as packaging film. Our release active packaging film based on photothermal agent provides a new insight to designing contactless intelligent active packaging.