Gluten-Based Composite Film for Smart Food Packaging Applications

Extensive research has been conducted on the potential applications of bioplastics from natural protein sources in active food packaging and edible coatings. However, their practical utility has been limited by their poor mechanical, barrier, antibacterial activity, and water resistance properties. Herein, we synthesized the biodegradable packaging film for the first time by blending curcumin (CCM) with wheat gluten (WG). The interaction between CCM and WG via hydrogen bonds has been confirmed through molecular docking studies and Fourier transform infrared spectroscopy (FTIR). X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and field emission scanning electron microscopy (SEM) results revealed a strong interaction of CCM with the WG matrix, leading to the formation of homogeneous packaging film up to 1.5% of CCM concentrations. Notably, the incorporation of CCM has significantly enhanced the mechanical strength, UV barrier capability, and antioxidant potential of the film, imparted hydrophobic characteristics to the film, and decreased the water vapor permeability. The water contact angle for WG-CCM 1.5 was improved to 82 degrees compared to the pristine WG film (58 degrees). Young's modulus of WG-CCM 1.5 is enhanced by threefold and found to be 8.43 MPa. An in vitro kinetic study revealed a controlled and gradual release of CCM from the film, following a biphasic release pattern described by diffusion- and desorption-limited kinetics, suggesting its suitability for sustained delivery applications. The antimicrobial activity of different samples was evaluated by measuring the zone of inhibition against Gram-positive and Gram-negative bacteria. The WG composite films demonstrated significant antibacterial activity, inhibiting the growth of E. coli (Gram-negative) and S. aureus (Gram-positive). Moreover, the composite film showed visible color alterations at different pH. WG-CCM 1.5 film was found to improve the shelf life of a fish sample and delay microbial spoilage. WG-CCM composite film, with improved mechanical, UV barrier, antioxidant, antimicrobial, and water resistance properties, has the potential to be a promising candidate for future food packaging and biomedical applications.