Chemical composition of Lippia origanoides Kunt. and Ocimum gratissimum L. essential oils stored at −20 °C

Abstract The objective of this work was to evaluate the chemical stability and quality of Lippia origanoides Kunt. Essential Oil (EO) samples compounds. and Ocimum gratissimum L. during storage. Two separate experiments with EO samples storage were performed, one involving the species L. origanoides Kunt. and the other with O. gratissimum L. For both species, a completely randomized design was used, in a split-plot in the time, with three replications. The primary factor was designated by the plots, consisting of two types of EO samples (extracted from fresh leaves and dried leaves) and the secondary factor consisted of four storage period (0, 3, 6 and 12 months). The EO samples was extracted by hydrodistillation and then stored in a freezer at −20 °C. At times 0, 3, 6 and 12 months of storage, chromatographic analysis of the samples was performed. It was observed that the EO samples extracted from fresh leaves of L. origanoides Kunt. and O. gratissimum L. showed greater stability in relation to chemical changes during storage. Regarding quality, the EO samples extracted from fresh leaves of L. origanoides Kunt. and the EO samples extracted from fresh and dried leaves of O. gratissimum L. showed an increase in the concentration of thymol and eugenol at twelve months of storage, representing an increase in the quality index of essential oils of these species.