TEMPO-Oxidized Bacterial Cellulose-Stabilized Clove Essential Oil Pickering Emulsions for Sustained-Release Sodium Alginate Active Packaging Films

Abstract

Developing biodegradable active packaging films that combine mechanical reinforcement, barrier improvement, antibacterial activity, and controlled release of natural antimicrobials remains challenging. Here, TEMPO-oxidized bacterial cellulose (TOBC) was used to stabilize clove essential oil (CEO) Pickering emulsions, which were incorporated into sodium alginate (SA) matrices. The effects of TOBC concentration on emulsion stability and emulsion loading on film-forming solutions, film structure, mechanical performance, barrier properties, antioxidant and antibacterial activities, and CEO release were evaluated. The emulsion stabilized with 0.7 wt% TOBC showed good visual stability after 30 days and was selected for film preparation. Moderate incorporation of the TOBC-stabilized CEO Pickering emulsion improved SA film performance, with SA-E10 showing the best overall balance. SA-E10 reached a tensile strength of 38.56 ± 1.66 MPa and an elongation at break of 10.27%, while the moisture content decreased from 36.48 ± 2.32% to 27.93 ± 0.46%. The films also showed enhanced UV-shielding capacity and lower water vapor permeability. Antioxidant activity increased with emulsion loading, reaching 71.43 ± 2.55% for DPPH and 83.66 ± 1.49% for ABTS. Film-coated paper disks showed visible inhibition zones against Escherichia coli and Staphylococcus aureus. Compared with direct CEO incorporation, the Pickering emulsion system delayed CEO release, indicating potential for sustained-release active packaging.