Fibras ultrafinas produzidas a partir de poli (ácido lático), lignina e óleo essencial de pimenta rosa (Schinus terebinthifolius Raddi) sobrepostas em filmes de amido para aplicação em embalagens de alimentos

Abstract

The present study aimed to produce bilayer films based on wheat or bean starch, overlaid with ultra-fine polylactic acid (PLA) fibers, lignin and pink pepper essential oil (PPEO). In the first chapter, ultrafine fibers of PLA and lignin at concentrations of 0.5, 1.5 and 2.5% were produced by the electrospinning technique. In this study, fibers with average diameters between 314 and 587 nm and thermal stability with degradation peak around 360 ºC were obtained. The wettability analysis showed that all treatments had a hydrophobic surface, with contact angles above 100°. Fibers containing 2.5% lignin exhibited greater antioxidant activities, with around 70% inhibition of DPPH and ABTS radicals. In the second chapter, fibers of PLA and PPEO were produced at concentrations of 10, 20 and 30%, being characterized by the same methodologies as in the previous chapter. In addition, the in vitro and in situ antimicrobial effect of the fibers was evaluated, which were applied to the lid of a simulated cream cheese package, replacing the conventional aluminum seal. The major component of the PPEO was myrcene and the lowest minimal inhibitory concentrations (MIC) and minimal bactericidal concentrations (MBC) were found against Staphylococcus aureus, with 256.9 and 385.3 mg/mL, respectively, and Listeria monocytogenes, with MIC of 513.8 and MBC of 642.3 mg/ml. Fibers applied to cream cheese packaging showed an inhibitory effect on the twenty-first day of storage for L. monocytogenes. For S. aureus, fibers inhibited colony growth on the fourteenth and twenty-first day, with reductions of 30 and 62%, respectively. In the third chapter, ultrafine fibers were produced with 8% PLA, 2.5% lignin and 30% PPEO, characterizing them according to the first chapter. For the formation of bilayer films, wheat starch films (WSF) and HTC beans (hard to cook) (BSF) were prepared and then the fibers were deposited on them. It was found that the set of WSF+PLA/lig/PPEO had higher opacity, with 71%. Treatment with BSF+PLA/lig/PPEO proved to be more rigid, with a tensile strength of 6.7 MPa and indicated greater elongation, with 45%, compared to treatment with WSF+PLA/lig/PPEO. It also exhibited lower moisture content, with 15%, and lower water solubility, with 16%. Regarding water vapor permeability, the treatment with BSF+PLA/lig/PPEO did not differ statistically from the WSF+PLA/lig/PPEO treatment, with approximately 2.0 g.mm/m²dia.kPa. Thus, both treatments are promising for application in food packaging due to the synergism of the set of polymers and bioactives used, which showed potential results in food preservation.