Structural, Physical, and Antifungal Characterization of Starch Edible Films Added with Nanocomposites and Mexican Oregano (Lippia berlandieri Schauer) Essential Oil.

The aim of this study was to evaluate the structural, physical, and antifungal characteristics of starch edible films added with nanocomposites and Mexican oregano (Lippia berlandieri Schauer) essential oil (EO). Starch edible films were formulated with Mexican oregano EO (0%, 1%, or 2% v/v) and bentonite or halloysite (2%). Physical properties such as L* (luminosity), hue, film thickness, and O2 and CO2 permeability were determined. Structural analysis was carried out via atomic force microscopy (AFM). Antifungal activity against Aspergillus niger, Fusarium spp., and Rhizopus spp. was evaluated. The addition of EO and nanocomposites reduced luminosity, providing color to the edible films. Film thickness increased through the addition of EO concentration. O2 and CO2 permeability was increased by bentonite/EO films, and for halloysite films, CO2 permeability decreased as EO concentration increased. The addition of EO with both nanocomposites shows an evident morphological change in film structure, decreasing pore density and increasing pore size. In general, Mexican oregano EO added to edible starch films has an adequate fungicidal effect. The most sensitive microorganism tested was A. niger. Edible films added with Mexican oregano EO and nanocomposites show better physical and antifungal properties due to an adequate structural change in the biopolymer matrix.

Antimicrobial activity of whey protein films supplemented with Lactobacillus sakei cell-free supernatant on fresh beef.

The aim of this work was to evaluate the antimicrobial activity of whey protein isolate (WPI) films supplemented with Lactobacillus sakei NRRL B-1917 cell-free supernatant on beef inoculated with Escherichia coli ATCC 25922 or Listeria monocytogenes Scott A; additionally, sensory evaluation was performed on wrapped beef cubes. Supernatant concentrates were obtained from Lb. sakei cultures in MRS broth after centrifugation, filtering, and freeze-drying. Films were prepared with WPI (3% w/w), alginate (0.625% w/w), rehydrated supernatant (18 mg/ml), and glycerol. Films were used to wrap beef cubes inoculated with ≈103 CFU/g E. coli or L. monocytogenes. Sensory evaluation was carried out on grilled beef wrapped or not with the studied antimicrobial films. During refrigerated storage, antimicrobial films reduced 1.4 log10 CFU/g of L. monocytogenes after 120 h, while E. coli decreased 2.3 log10 CFU/g after 36 h. Grilled beef wrapped with antimicrobial film was well accepted by panelists, besides scores evidenced no significant differences (p > 0.05) between wrapped and unwrapped beef.