Variations in chemical compositions of essential oil from sour orange (Citrus aurantium L.) blossoms by different isolation methods

The main goal of this research was to study the impact of different extraction methods on the yield and chemical compositions of essential oil (EO) obtained from sour orange blossoms. Seven different methods were used for the purpose of extracting the EOs, namely, commercial hydrodistillation (CoM), hydrodistillation (HD), steam distillation (SD), Ohmic-assisted hydro distillation (OAHD), solvent-less microwave extraction (SLME), solvent-free microwave extraction (SFME), and microwave-assisted hydrodistillation (MAHD). The isolated EOs were analyzed by GC and GC-MS in three replications. The highest EO yield in relation to the extraction time was obtained by the HD method (0.34%) and the lowest one (0.04%) was detected by the SD method. The main compounds and their ranges of concentration in the EOs were as follows: linalool acetate (12.2 ± 0.08–28.9 ± 0.2) %, linalool (22.9 ± 0.07–54. ± 0.2) %, Farnesol (0.2 ± 0.04–10.4 ± 0.07) %, E-nerolidol (0.4 ± 0.1–21.4 ± 0.04) % and geranyl acetate (0.97 ± 0.05–9.3 ± 0.08)%. Moreover, SLME caused a selective extraction of E-nerolidol (21.42%) and farnesol (10.45%). The SFME resulted in a two-fold extraction of linalool (54.08%), compared to the COM which yielded an amount of 22.9%. Significant changes in the amounts of limonene (1−14) % and β-pinene (0–9.6)% were also observed by the extraction methods. Overall, the results suggest that MAHD and SFME can be termed as green technologies because of their less energy requirements and less carbon dioxide emissions. Their high-quality EO and cost effective performance for EO extraction can be of importance to pharmaceutical industries.