Performance of bacterial nanocellulose packaging film functionalised in situ with zinc oxide: migration onto chicken skin and antimicrobial activity

Zinc oxide nanoparticles (ZnO) are cost-effective antimicrobial agents with great potential for the active packaging industry. Bacterial NanoCellulose (BNC) features a porous fibre network, with high absorption capacity, flexible and with good mechanical properties, suitable as a carrier of active agents. In this work, BNC_ZnO films were developed and optimized regarding the particle size and ZnO concentration. The NaOH dropwise addition to BNC membranes immersed in Zn(CH₃COO)₂-PVOH enabled the production of ZnO nanoparticles with an z-average of 144 nm and a low polydispersity index. High ZnO incorporation (∼27%m_Zn/m_BNCZnO) was obtained, with uniform distribution all over the BNC membranes. These composites were then characterized and evaluated for Zn migration using food simulants (10%, 20%, and 50% ethanol) with results lower than the limit. Migration into chicken skin, as a real food model, was low at 4 °C but exceeded the migration limit at 10 and 22 °C. Zn migration was also found to be temperature and pH dependent. When applied to chicken skin, BNC_ZnO was effective against E. coli, Salmonella (0.5–1.0 log reduction), and Campylobacter spp. (2.0 log reduction), indicating its potential for active packaging applications.