Citral Chemotype of Pectis elongata Essential Oil: Nanoemulsification and Enhanced Antimicrobial Properties for Food Safety

Abstract

Aims: Essential oils of Pectis elongata from the Brazilian Amazon were analyzed to estimate the citral (neral and geranial stereoisomers) content in the vegetative and reproductive phases and their circadian cycle. Also, a nanoemulsification bioassay was performed to determine its impact on the oil composition and antimicrobial effectiveness against food contaminant agents. Methodology: Gas chromatography (GC) and gas chromatography coupled to mass spectrometry (GC-MS) analyzed the oil composition, nanoemulsion, and the citral standard. Nanoemulsion was prepared using low-energy input methodology with phase inversion, and its mean diameter, polydispersity index, and volatile composition were evaluated on the 1st, 7th, and 15th-day post-processing. Results: The citral content of P. elongata oil ranged from 70.0% to 92.5% in the performed studies. The disk diffusion and minimum inhibitory concentration bioassays conducted with the emulsified essential oil exhibited antimicrobial activity that was two to four times greater than the oil itself, with this nanoemulsion showing an average diameter between 140.7 ± 6.79 and 177.07 ± 9.24 nm, a polydispersity index between 0.36 and 0.47 ± 0.09, and a zeta potential between -2.54 ± 2.6 and -7.25 ± 2.37. Conclusion: Citral was maintained as the oil main constituent, preserving its biological properties and significantly enhancing its antimicrobial activity against various pathogenic agents contaminating and spoiling food. These findings highlight the potential application of a citral-rich oil nanoemulsion to enhance food safety.