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Biodegradable poly(butylene adipate-co-terephthalate) (PBAT) films incorporated with nisin were prepared with concentrations of 0, 1000, 3000, and 5000 international units per cm(2) (IU/cm(2)). 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 x 10(11) g m m(-2) s(-1) Pa(-1) and from 4.80 x 10(7) to 11.26 x 10(7) mL.m.m(-2).d(-1).Pa(-1), respectively. The elongation at break (epsilon(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 (sigma(s)) (P < 0.05). The glass transition and melting temperatures with the presence of nisin ranged from -36.3 to -36.6 degrees C and from 122.5 to 124.2 degrees 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 2theta from 8 degrees to 35 degrees . 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.

Biopolymer films were developed from apple peels of apple process co-products and their physical properties were determined. Apple peel-based films with glycerol (23%, 33%, and 44%[w/w, dry basis]) were prepared using high-pressure homogenization (HPH) at different levels of pressure (138, 172, and 207 MPa). An evaluation of the rheological properties (elastic modulus [G'], viscous modulus [G''], and viscosity) of the film-forming solutions was performed. For the apple peel films, the water sorption isotherms, the kinetics of water absorption, the water vapor permeability (WVP), the oxygen permeability (OP), and the tensile properties were determined. The G' and viscosity of the film-forming solutions decreased significantly with increasing processing pressure (P < 0.05). However, no difference was observed in G'' values at different homogenization pressures (P > 0.05). The viscosity decreased from 644 to 468 kPa.s as the pressure increased from 138 to 207 MPa at 90 degrees C. The monolayer water content of the apple peel films decreased with increasing content of glycerol from 23% to 33%. Further increase in glycerol content did not change the monolayer water content. The water diffusion coefficient of the films was highest at the intermediate level of glycerol content. The barrier properties (WVP and OP) of the films increased with increasing level of glycerol, while processing pressure did not influence the gas barrier properties. The films prepared at 207 MPa were less stiff and strong, but more stretchable than those prepared at 138 and 172 MPa.