Improving the functional properties of chitosan-curcumin films using microwave

Recently, bio-based polymers have been utilized in packaging film production as a sustainable alternative to non-renewable synthetic plastics. This study aimed to evaluate the effects of microwaves on the functional properties of chitosan incorporated with curcumin (CSCur), and to determine the optimal microwave duration to enhance these properties. The films were subjected to microwave treatment for 30, 60, and 120 s at a constant power of 800 W and were analyzed for thickness, color/opacity, water solubility, mechanical strength, vibration, crystallinity, and surface morphology and compared to untreated samples. The results indicated that the microwave treatment did not significantly affect the thickness (ANOVA, p>0.05). However, the 120-second treatment significantly improved color (ANOVA, p<0.05) (L*: 30.70, a*: 1.91, b*: 8.93), opacity (2.19), reduced water solubility (47.51% unheated, 59.96% heated), and increased crystallinity (17.35%) compared to untreated and shorter treatment durations. Conversely, the highest tensile strength (1.30 MPa) was observed at 60 s because strength reduction occurred beyond this duration. FESEM analyses revealed that the microwave-treated CSCur films had smoother and denser surfaces with fewer pores. The changes detected in ATR-FTIR and XRD supported the observed improvements in mechanical and barrier properties, indicating rigidification of the hydrophilic domains at the OH/NH moiety and fluidization of the hydrophobic domains at the CH moiety, along with a significant increase in the crystallinity index (ANOVA, p<0.05). Thus, 120 s of microwave treatment is recommended to optimize the chitosan films incorporated with curcumin.