Furan-based polyesters loaded with nisin for sustainable antimicrobial packaging

This work focuses on the realization of fully bio-based blends from two different furan-based polyesters and natural preservatives, to obtain innovative/active food packaging. As preservative, nisin, a polycyclic antibacterial peptide produced by Lactococcus lactis, was mixed in 2.5 wt% amount, with the homopolymer poly(trimethylene furanoate), PTF, and the copolymer poly(butylene/pentamethylene furanoate), P(BPeF). The mechanical properties of the blends evidenced a modulation for flexibility and toughness, in particular in P(BPeF), owing to the presence of nisin, keeping at the same time the thermal stability, which is a key feature of these polyesters, as well as their thermal transitions.The evaluation of the functional properties highlighted the preservation of excellent gas barrier characteristics of PTF and P(BPeF). Lastly, the addition of nisin allows for the implementation of antibacterial features,absent in the pristine polymers, as the blends showed antimicrobial activity, by disc diffusion assay, against Lactiplantibacillus plantarum and Listeria monocytogenes. PTF containing 2.5% nisin were tested also in ACE juice, pH 4.5, inoculated with Listeria monocytogenes at 10^2 CFU/mL and stored at 4°C. L. monocytogenes growth was checked for 12d. After 8 d, it decreased under the detection limit in the sample with active packaging. In the control sample, the pathogenic species remained constant during the juice shelf-life.