Biodegradable Poly(butylene adipate-co-terephthalate) Films Incorporated with Nisin: Characterization and Effectiveness against Listeria innocua

ABSTRACT: Biodegradable poly(butylene adipate-co-terephthalate) (PBAT) films incorporated with nisin were prepared with concentrations of 0, 1000, 3000, and 5000 international units per cm² (IU/cm²). All the films with nisin inhibited Listeria innocua, and generated inhibition zones with diameters ranging from 14 to 17 mm. The water vapor permeability and oxygen permeability after the addition of nisin ranged from 3.05 to 3.61 × 10¹¹ g m m⁻² s⁻¹ Pa⁻¹ and from 4.80 × 10⁷ to 11.26 × 10⁷ mL·m·m⁻²·d⁻¹·Pa⁻¹, respectively. The elongation at break (ɛ_b) was not altered by the incorporation of nisin (P > 0.05). Significant effect was found for the elastic modulus (E) and the tensile strength (σ_s) (P < 0.05). The glass transition and melting temperatures with the presence of nisin ranged from −36.3 to −36.6 °C and from 122.5 to 124.2 °C, respectively. The thermal transition parameters such as the crystallization and melting enthalpies and crystallization temperature were influenced significantly (P < 0.05) by incorporation of nisin into films. The X-ray diffraction patterns exhibited decreasing levels of intensity (counts) as the concentration of nisin increased in a range of 2θ from 8° to 35°. Formation of holes and pores was observed from the environmental scanning electron microscopy images in the films containing nisin, suggesting interaction between PBAT and nisin.