Caracterização das propriedades funcionais de filmes ativos antimicrobianos aditivados com óleos essenciais e plastificante

Abstract

The use of active packaging incorporated with natural antimicrobials as essential oils (EOs) for food preservation is a modern concept for the food industry. The objective of this study was to characterize cellulose acetate film (CA) incorporated with EOs and their combinations and/or added plasticizer, evaluating the influence of additives on the behavior of these materials. It is characterized as the thickness of the films, visual aspect, chemical structure, surface, mechanical strength, water vapor rate of transmission (WVRT) and antimicrobial activity. Through technique "casting" were obtained films incorporated with 50% (w/v) of EOs oregano or cinnamon or sweet fennel or combinations thereof and/or glycerol (5, 10, 20 and 30% (w/v)). Having as controls only films containing 50% (w/v) glycerol, and CA pure film, a total 41 treatments. The incorporation of EOs did not change the thickness and transparency of the films, but it reduced the WVRT. The color parameters L *, a* and b* were affected by the incorporation with EOs and/or glycerol the films exhibited clear with different colors compared with the AC pure film. Incorporating the most EOs cause increased tensile strength (TS) of the modulus of elasticity (ME) and reduced elongation at break (EB), except for the film with fennel EO (FEO) who presented plasticizer power differing from the other for all the evaluated mechanical parameters. The drilling force (DF) has increased to most films EOs incorporated with the exception of the film incorporated with the three EOs. The scanning electron microscopy (SEM) images revealed that most of the EOs and their combinations did not cause changes in the surface and cross-sectional area of the films, except the film with FEO. In the spectra of infrared spectroscopy with Fourier transform (FTIR), it observed that the interactions between the polymer matrix and most EOs were similar except for the film with FEO. As for the antibacterial efficiency in vitro, only the film incorporated with FEO showed no efficacy against Staphylococcus aureus (Gram +) and Escherichia coli (Gram +). It was observed that glycerol causes increased thickness and WVRT the AC films, however, the active films with EOs does not modify the parameter to most treatments. Transparency was not affected for most films. The addition of glycerol for most films incorporated with EOs caused reduction of TS, the ME and increased EB and DF. From the SEM pictures it can be observed that the glycerol promoted the emergence of porous structures, networked or compact, depending on the EO concentration and glycerol. The FTIR spectral showed that glycerol has different interactions, depending on the embedded EOs. The antibacterial efficiency of films with EO oregano or cinnamon or oregano more cinnamon has been improved with the presence of glycerol, while the others were not affected. In the face of changes in functional properties observed, it appears that with the additivation materials it is necessary to characterize them to define their applicability