Effect of Postharvest Drying on the Composition of Mexican Oregano ( <i>Lippia graveolens</i> ) Essential Oil

Abstract

Mexican oregano (Lippia graveolens), an aromatic herb harvested in the wild, represents a significant income for rural households. Despite the economic importance of Mexican oregano, however, no information on the effects of postharvest drying on the chemical composition of the essential oil is available. In this study, the chemical composition of Mexican oregano essential oil from plants dried under four treatments, including shade, sun, and oven at 20 and 40°C, were compared. A gas chromatography/mass spectrometry (GC/MS) analysis of the oil was used to identify six major components and their mean percentages in the oil: carvacrol (62.2%), p-cymene (6.8%), thymol (5.9%), trans-caryophyllene (4.9%), γ-terpinene (4.0%), and α-caryophyllene (3.1%). Postharvest drying treatments had no effect on either the qualitative or quantitative composition of the Mexican oregano oil. The percentages of carvacrol detected in the essential oil of individual Mexican oregano plants growing in Yucatán are the highest reported to date for the species, suggesting that the studied individuals belong to the carvacrol chemotype and may have a significant economic value.