In situ multi-crosslinked bacterial cellulose with enhanced mechanical and barrier properties for antimicrobial food contact packaging

To mitigate environmental pollution and food contact safety concerns associated with traditional non-biodegradable plastic packaging, biodegradable and edible polysaccharide-based materials such as bacterial cellulose (BC) can serve as an ideal alternative for food packaging. In this paper, BC/Nisin/SA-PBA composite films were prepared using an in situ multi-crosslinking strategy to enhance the mechanical strength, barrier performance, and antimicrobial activity of BC films. The goal was to develop biodegradable and food-contact safe packaging films based on BC composites. Specifically, amphiphilic alginate derivatives (SA-PBA) were synthesized and incorporated during the bacterial cellulose biosynthesis together with Nisin, while subsequent cross-linking with Ca 2+ was performed after harvest. Compared to pure BC film, the BC/Nisin/SA-PBA composite film containing 0.2 wt% SA-PBA exhibited significant improvements in mechanical properties, with tensile strength (TS) increasing by 3.08 times (24.77 MPa) and elongation at break (EAB) increasing by 37.51 times (16.13%). The oxygen transmission rate (OTR) and water vapor permeability (WVP) decreased by 98.11% and 80.93%, respectively. Additionally, the composite film demonstrated excellent antimicrobial activity, particularly against Staphylococcus aureus , and extended the shelf life of pork to 10 days at 4 °C. The film significantly reduced the total volatile basic nitrogen (TVB-N) and total viable count (TVC), indicating its potential for preserving food quality. This work proposes a novel in situ multi-crosslinking strategy to develop biodegradable, food-safe, and high-performance food packaging materials.