Synthesis, characterization, and evaluation of antibacterial properties of silver/ carboxymethyl cellulose/ bacterial cellulose/ Clitoria ternatea extract aerogel composites

Food packaging for meat, processed food, and fresh food is often equipped with adsorbent pads to regulate moisture. However, most adsorbents are derived from synthetic polymer materials. There has been increasing demand for functional packaging materials that are not only durable, cost-effective, and well-designed, but also capable of extending the product shelf-life. Butterfly pea (Clitoria ternatea L.) flowers and silver nanoparticles have been reported to exhibit antibacterial activity in several studies. This study aimed to synthesize novel aerogel composites made of carboxymethyl cellulose (CMC), bacterial cellulose (BC), and C. ternatea flower extracts as adsorbent material in food packaging. BC was used as a reinforcing agent. The composites were synthesized by reacting silver solution and carboxymethyl cellulose, and then adding bacterial cellulose and C. ternatea extracts. Three different ratios of C. ternatea extract i.e. 0.5 %, 1 % and 2 % were used in this study (AT1, AT2, AT3). These aerogel composites were tested against four pathogenic bacteria i.e. Staphylococcus aureus, Eschericia coli, Pseudomonas aeruginosa, and Salmonella Typhimurium using disk diffusion and microdilution methods. The aerogel composites were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray fluorescence (XRF), Fourier-transform infrared (FTIR) spectroscopy, and color analysis. The results showed that AT3 had good antibacterial activity against P. aeruginosa, S. Typhimurium, and S. aureus with inhibition zones of 10.14 mm, 11.63 mm, and 7.69 mm, respectively, while composite AT2 had good inhibition against E. coli with the value of 9.82 mm. Equipped with good antibacterial activity, these aerogel composites have excellent potential to be used as adsorbent pads in food packaging to prolong the food shelf-life.