Biobased Formulations Made of Poly(trimethylene furanoate) Loaded with Nisin for Sustainable Antimicrobial Packaging

In the present study, biobased nisin-containing formulations were prepared to obtain innovative, sustainable, and active food packaging. Poly(trimethylene furanoate) (PTF) was blended with three different amounts of commercial nisin powder (0.05, 1.0, and 2.5 wt %; Sigma-Aldrich, 2.5% active nisin, balance NaCl), corresponding to 0.0125, 0.25, and 0.625 mg of active nisin/g of polymer, respectively. Circular films (Ø = 11 cm, thickness ≈ 200 μm) were obtained by compression molding. The high thermal stability and barrier properties of PTF have been maintained, while mechanical properties and surface wettability were tuned thanks to the introduction of nisin. Lastly, the addition of this active agent allows for the implementation of antibacterial features, absent in the pristine PTF. When tested in ACE juice inoculated with Listeria monocytogenes, films containing 1.0 and 2.5 wt % of nisin powder (0.25 and 0.625 mg active nisin/g polymer) reduced the Listeria load below the detection limit during storage, whereas Listeria counts in the controls remained constant throughout the juice shelf life.