Characterization and Inhibitory Effects of Essential Oil and Nanoemulsion from Ocotea indecora (Shott) Mez in Aspergillus Species

The Aspergillus genus, the etiological agent of aspergillosis, is an important food contaminant and mycotoxin producer. Plant extracts and essential oils are a source of bioactive substances with antimicrobial potential that can be used instead of synthetic food preservatives. Species from the Lauraceae family and the Ocotea genus have been used as traditional medicinal herbs. Their essential oils can be nanoemulsified to enhance their stability and bioavailability and increase their use. Therefore, this study sought to prepare and characterize both nanoemulsion and essential oil from the Ocotea indecora’s leaves, a native and endemic species from the Mata Atlântica forest in Brazil, and evaluate the activity against Aspergillus flavus RC 2054, Aspergillus parasiticus NRRL 2999, and Aspergillus westerdjikiae NRRL 3174. The products were added to Sabouraud Dextrose Agar at concentrations of 256, 512, 1024, 2048, and 4096 µg/mL. The strains were inoculated and incubated for up to 96 h with two daily measurements. The results did not show fungicidal activity under these conditions. A fungistatic effect, however, was observed. The nanoemulsion decreased the fungistatic concentration of the essential oil more than ten times, mainly in A. westerdjikiae. There were no significant changes in aflatoxin production.