Silver/bacterial cellulose/Clitoria ternatea composite film for packaging application: synthesis, characterization and antibacterial properties

This study aimed to develop novel composite films made of Ag, bacterial cellulose (BC), and Clitoria ternatea flower extract for food packaging applications. The films were synthesized using varying concentrations of Ag ion (10(-3)-10(-1) M) and flower extract (0-2x10(4) mu g/ml), followed by characterization using scanning electron microscopy-energy dispersive X-ray (SEM-EDX), X-ray diffraction (XRD), and Fourier-transform infrared (FTIR) spectroscopy. The antibacterial activity of the films was assessed against five bacteria, including Escherichia coli, Salmonella Typhimurium, Pseudomonas aeruginosa, Bacillus subtilis, and Staphylococcus aureus. The composite films appeared opaque and slightly dark. A porous network of microfibrils was observed under SEM, and higher Ag concentrations resulted in a rougher film surface. Higher Ag+ and extract concentrations resulted in higher percentages of Ag deposited on the surface, as confirmed by EDX (up to 34.7% at 2x10(4) mu g/ml extract and 10(-1) M Ag+). Ag/BC/C. ternatea extract combinations generally exhibit higher antibacterial activity than pure BC film. The highest inhibition of S. Typhimurium, P. aeruginosa, and B. subtilis was achieved by a composite film made with 10(-1) M Ag+ and 2x10(4) mu g/ml extract with inhibition values of 7.78 mm, 8.12 mm, and 8.25 mm, respectively. All tested composite films also had lower water vapor sorption capacity (2.31-6.71%, depending on the compositions) than BC (6.93%), enabling better protection of the preserved food from surrounding moisture. The Ag/BC/C. ternatea extract composite films are promising, sustainable packaging materials for preserving food quality.