Optimising essential oil yields and quality from <i>Pimenta dioica</i> (L.) merr. Leaf: impact of NaCl concentrations, pH media and sequential separation of essential oil components during hydrodistillation

The study examined the effects of herb drying, salt concentration, pH, and sampling approach on essential oil yield and composition in <i>Pimenta dioica</i> (L.) Merr. Fresh samples yielded higher essential oil (EO) (1.25%) than shade-dried ones. Increasing NaCl concentration correlated with higher EO yields, while a basic pH favoured superior yields. Gas Chromatography identified Eugenol and β-myrcene as primary constituents. Eugenol content peaked at 10% NaCl (56.429%) and was lowest at pH 4 (42.850%). β-myrcene content was highest at pH 4 (31.476%). Hydro distillation with systematic sampling evaluated the effects of 14 fractions in different time frames. Phenylpropanoids (mainly eugenol) and acyclic monoterpene (mainly β-myrcene) dominated all fractions, with cyclic monoterpene (mainly limonene) enriched in the first four fractions. Fractions 10 to 14 showed significant increases in eugenol compared to the control. These findings provide insights for meeting market demands, enhancing the commercial potential of <i>P. dioica</i> EO.