Potencial antifúngico e antiocratoxigênico do óleo essencial de Rosmarinus officinalis e Callistemon viminalis encapsulados em nanofibras de PLA frente aos fungos do gênero Aspergillus

Abstract

Food contamination by microorganisms has caused significant losses for industries because of the deterioration of food, as well as the production of mycotoxins. Essential oils, a complex mixture of various constituents, play an important role in controlling fungal contamination because of their biological properties. The essential oil has been incorporated into nanofibers, seeking to increase its stability, avoiding volatilization and degradation, obtain a controlled release of its compounds. The objectives of this work were to extract and chemically characterize the components of the essential oils from Rosmarinus officinalis and Callistemon viminalis; to produce nanofibers of poly(lactic acid) (PLA) containing the essential oils by means of solution blow spinning (SBS); to physicochemically characterize the nanofibers and evaluate the in vitro antifungal and antimycotoxigenic activity of the nanofibers, the essential oils, and the monoterpene 1,8-cineol against Aspergillus carbonarius, Aspergillus niger, Aspergillus ochraceus and Aspergillus westerdjikiae. The essential oils were extracted by hydrodistillation, characterized and quantified by gas chromatography coupled to a mass spectrometer (GC/MS) and gas chromatography with a flame ionization detector (GC/FID). The nanofibers produced were characterized by scanning electron microscopy (SEM), nfrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The antifungal and antiocratoxigenic activities were evaluated by the fumigation method, and the morphological analysis of the microorganisms by SEM. The principal compounds found in the essential oil from R. officinalis were 1,8-cineole and camphor and those in the essential oil from C. viminalis were 1,8-cineole and α-pinene. Electromicrographs showed an increase in the diameter of nanofibers containing an essential oil. The antifungal potential was significant for all concentrations of the essential oil and nanofibers tested, and there was no inhibition of mycelial growth only for the fungus A. niger. The production of ochratoxin A by the fungi A. carbonarius, A. niger, A. ochraceus and A. westerdijkiae was inhibited by treatments with the essential oil, nanofibers incorporated with the oil and by the monoterpene 1,8-cineole. The results suggest that essential oils and PLA nanofibers can be promising and viable for application in the food industry to control toxigenic fungi and ochratoxin A.