Volatile compounds of leaves and fruits of Mangifera indica var. coquinho (Anacardiaceae) obtained using solid phase microextraction and hydrodistillation

Volatile compounds present on fruits and leaves of Mangifera indica var. coquinho were investigated by headspace solid phase microextraction (HS-SPME) and hydrodistillation (HD). Conventional techniques, such as hydrodistillation, may impart chemical changes to the original oil composition being also time-consuming. On the other hand, HS-SPME provides solvent-less extractions, shorter extraction times and may supply complementary information about the composition of the compounds. The HS-SPME technique was previously evaluated by the comparative study among the fibres: commercial PDMS, NiTi-ZrO₂ and NiTi-ZrO₂-PDMS. The fibre NiTi-ZrO₂-PDMS showed better sensitivity and precision and was used on the extraction of components. The influence of several parameters like the time and temperature of extraction and desorption time were examined to obtain better efficiency. Fruits and leaves were analysed in mature and immature stages. The profiles corresponding to the volatile compounds detected by both techniques are discussed.     

Comparison of essential oils of clove buds extracted with supercritical carbon dioxide and other three traditional extraction methods

Supercritical fluid extraction (SFE) of essential oil from clove buds with CO₂ was explored. The effect of different parameters, such as temperature (30 °C, 40 °C, 50 °C), pressure(10 MPa, 20 MPa, 30 MPa) and particle size (three degree index), on the extraction yield and the content of eugenol in extracts was investigated using three-level orthogonal array design. The experimental results show that the temperature has the largest effect on the eugenol content of the extracts, and particle size has the maximum effect on the oil yield. The essential oil of 19.56% yield, in which the maximum content of eugenol in extracts is 58.77%, can be extracted from clove buds at pressure of 10 MPa and temperature of 50 °C. Essential oil of clove buds obtained by SFE, hydrodistillation, steam distillation and Soxhlet extraction were further analyzed by gas chromatography/mass spectrometric detection to compare the extraction methods. Twenty three compounds in the clove oils have been identified, showing that the composition of the clove oil extracted by different methods is mostly similar, whereas relative concentration of the identified compounds is apparently different. General characteristics of the clove oils obtained by different methods were further compared, and SFE is considered as the optimum process among the four processes for obtaining clove oil with high quality.     

Supercritical fluid extraction of wormwood (Artemisia absinthium L.)

The objective of the work was to optimize the extraction of wormwood oil by supercritical fluid extraction (SFE) of growth-controlled plant material. Different extraction conditions, two growth techniques and various crops were tested and the evolution of the extracted oil composition was screened chromatographically. A comparison with conventional techniques such as hydrodistillation (HD) or organic solvent extraction (OSE) was also presented. Particularly, six CO₂ densities ranging from 285.0 kg/m³ to 819.5 kg/m³ were studied in the range of 9.0-18.0 MPa and 40-50 °C. A systematic study was carried out with plant material from 2005, while SFE of 2006, 2008 and aeroponically grown crops was performed for comparative purposes. The effect of ethanol as a modifier of the supercritical fluid extraction was also studied. The major compounds found in the SFE extracts as well as in the HD essential oils were Z-epoxyocimene, chrysanthenol and chrysanthenyl acetate. A model based on mass transfer equations, the Sovová model, was successfully applied to correlate the experimental data.     

Comparative evaluation of the antibacterial activities of the essential oils of Rosmarinus officinalis L. obtained by hydrodistillation and solvent free microwave extraction methods

Rosmarinus officinalis L. is a perennial herb that belongs to the Lamiaceae family. It is used as a food flavouring agent, and well known medicinally for its powerful antimutagenic, antibacterial and chemopreventive properties. Essential oils were obtained from this plant by hydrodistillation (HD) and solvent free microwave extraction (SFME). GC–MS analyses of the oils revealed the presence of 24 and 21 compounds in the essential oils obtained through HD and SFME, respectively. The total yield of the volatile fractions obtained through HD and SFME was 0.31% and 0.39%, respectively. Higher amounts of oxygenated monoterpenes such as borneol, camphor, terpene-4-ol, linalool, α-terpeneol (28.6%) were present in the oil of SFME in comparison with HD (26.98%). However, HD oil contained more monoterpene hydrocarbons such as α-pinene, camphene, β-pinene, myrcene, α-phellanderene, 1,8-cineole, trans β-ocimene, γ-terpenene, and cis sabinene hydrate (32.95%) than SFME extracted oil (25.77%). The essential oils obtained using the two methods of extraction were active against all the bacteria tested at a concentration of 10 mg ml⁻¹. Minimum inhibitory concentration (MIC) values for all the susceptible bacteria ranged between 0.23 mg ml⁻¹ and 7.5 mg ml^−1.     

Evaluation of four isolation techniques for honey aroma compounds

The analysis of the volatile fraction of honey provides useful information for the determination of the botanical and geographical origin. However, the results obtained vary greatly upon the extraction procedure employed. Four different isolation techniques were compared, that is hydrodistillation (HD), micro‐simultaneous steam distillation–solvent extraction (MSDE), ultrasound‐assisted extraction (USE) and solid‐phase microextraction (SPME). From the data obtained, USE and SPME seem to be more suitable for the isolation of potent marker compounds. HD and MSDE have main drawbacks because of the drastic conditions used that lead to the formation of artefacts and the degradation of sensitive compounds. These drawbacks are avoided when employing USE and SPME. Copyright © 2004 Society of Chemical Industry     

An experimental design approach for the extraction of volatile compounds from turmeric leaves (Curcuma domestica) using pressurised liquid extraction (PLE)

Pressurised liquid extraction (PLE) was used to obtain an oleoresin from aromatic turmeric leaves. Four major compounds, which constituted 72% oleoresin, were monitored during the optimisation study. Components in the extract were identified using GC/MS and retention indices. Based on maximum extraction of 1,8-cineole, the optimised operating conditions for PLE, were heating at 147 °C, a pressure of 7150 kPa and a static time of 17 min. The results obtained were compared with conventional isolation procedures, hydrodistillation and Soxhlet extraction, whereby the proposed method was found to be better in term of quantity of the targeted oleoresin compounds, namely, α-phellandrene, p-cymene, 1,8-cineole and terpinolene.     

Comparison of essential oil compositions of Salvia mirzayanii obtained by supercritical carbon dioxide extraction and hydrodistillation methods

Essential oil of Salvia mirzayanii cultivated in Iran was obtained by hydrodistillation and supercritical (carbon dioxide) extraction methods. The oil was analysed by capillary gas chromatography using flame ionization and mass spectrometric detections. The compounds were identified according to their retention indices and mass spectra (EI, 70 eV). The effects of different parameters such as pressure, temperature, modifier volume and extraction times (dynamic and static) on the supercritical fluid extraction (SFE) of S. mirzayanii oil were investigated. The results showed that, under a pressure of 35.5 MPa, temperature of 35 °C, 6% methanol, dynamic extraction time of 50 min and static extraction time of 30 min, extraction was more selective for the linalyl acetate. Thirty four compounds were identified in the hydrodistilled oil. The major components of S. mirzayanii were linalyl acetate (7.6%), 1,8-cineole (8.0%), linalool (9.0%) and 8-acetoxy linalool (11.0%). However, by using supercritical carbon dioxide in optimum conditions, only three components contain more than 63% of the oil. The yield of the obtained oil based on hydrodistillation was 2.20% (v/w). Extraction yield based on the SFE varied in the range of 1.50–9.67% (w/w) under different conditions. The results revealed that, in Iranian S. mirzayanii oil, linalyl acetate is a major component.     

Supercritical carbon dioxide extraction of volatile oil from Italian coriander seeds

Supercritical CO₂ fluid extraction of the volatile oil from Italian coriander seeds was carried out under different conditions of temperature (40 and 50 °C), pressure (90, 100 and 150 bar), mean particle size (0.4, 0.6 and 0.8 mm) and CO₂ flow rate (0.79, 1.10 and 1.56kg/h) in order to evaluate their influence on the yield and composition of the volatile oil. Hydrodistillation with the same mean particle sizes was performed and used as a comparative method. The best supercritical fluid extraction conditions were found to be 90 bar, 40 °C, 1.10 kg/h and 0.6 mm. The chemical composition of each supercritical fluid extraction sample was analysed by GC and GC–MS and the global composition was compared with that obtained by hydrodistillation. The dominant components were linalool (65–79%), γ-terpinene (4–7%), camphor (3%), geranyl acetate (2–4%), α-pinene (1–3%), geraniol (1–3%) and limonene (1–2%). Moreover, supercritical fluid extraction samples were collected at specific intervals of amount of CO₂ consumed, during each extraction, and the contribution of the main volatile components from each sample, for the global volatile compositions, was evaluated. In general, the first sample of each extraction contained up to 50% of the mass of each component.     

Experimental Study and Modeling of Essential Oil Extraction from Plants by Hydrodistillation

Hydrodistillation of essential oils from leaves of myrtle, rosemary, and sour orange was experimentally studied and the extraction process was modeled. A mass balance was carried out over an assumed flat leave particle and the use of Fick's second law of diffusion led to the mass transfer equation. Its resolution required adequate boundary and initial conditions. The model considered the effect of the main processing parameters on the overall essential oil extraction efficiency as well as the determination of the optimum conditions. To assess the reliability of the model, yield curves for all studied conditions and variation of the oil composition with time were compared with the experimentally obtained results for each plant leave. The agreement seems to be reasonable, although some refining of the model is necessary by taking into account both the diffusion and reaction contributions.     

Effects of Operating Parameters on the Cinnamaldehyde Content of Extracted Essential Oil Using Various Methods

Supercritical fluid extraction (SFE) of essential oils from commercial cinnamon bark was compared with essential oils that were obtained by hydrodistillation. Effects of operating parameters (pressure, temperature and extraction time of SFE) on the extraction yield and the composition of the extracted volatile oil were studied. Moreover, in the hydrodistillation process, the effect of the pH of the solvent on the concentration of cinnamaldehyde in the extracted volatile oil was studied. The maximum yield of extract in the SFE process is about 7.8 % at 70 °C and 240 bar. The maximum concentration of cinnamaldehyde in the SFE process was obtained at 70 °C and 160 bar, and the maximum concentration of this component in hydrodistillation was achieved at pH = 4.1.