Dual pH-responsive packaging film based on modified bacterial cellulose Pickering emulsion: impact of anthocyanin...

In this study, bacterial cellulose (BC) was functionally modified to obtain BC-COOH nanoparticles, which were used to prepare Pickering emulsions (5-25%, v/v). The 10% oil emulsion showed optimal stability with a droplet size of 6.67 μm, a zeta potential of -45.16 mV, and pronounced pH sensitivity. The dual pH-responsive packaging films, featuring both triggered-release and indicator functions, were prepared by incorporating different anthocyanin (Ant) concentrations (0-0.1 mg/mL) into emulsion/sodium alginate composite (EC) (10%, v/v). The composite film with 0.02 mg/mL Ant (0.02Ant/EC) showed enhanced tensile strength and elongation at break, reaching 16.43 MPa and 84.12%. The film also showed good light barrier, hydrophilicity, and antioxidant activity, and was therefore selected for dual pH-responsive analysis. This film showed reversible visible color changes across pH 2-13. The cumulative release of essential oil reached 0.254 μL/mg over 36 h at pH 10.0, representing a 37.79% increase compared to release at pH 7.2.