The extraction methods of white cardamom essential oil are commonly used steam distillation method and solvent extraction method. The former is widely used. In recent years, some new methods for extracting plant essential oils have also been developed, mainly microwave-assisted steam distillation and supercritical CO2 extraction methods.
In some laboratory studies, the essential oil of white cardamom was extracted by steam distillation, and the extraction process was optimized by orthogonal experiments. The amount of water added and the extraction time had no significant effect on the yield of essential oils, and there was no statistical significance.
Extraction of White Cardamom Essential Oil by Steam Distillation
In the experiment, white cardamom was ground through a 20-mesh sieve, added 6 times of water, and extracted for 4 hours. According to the determined optimal extraction process, the relative standard deviation (RSD) of 3 repeated experiments was 2.65%. The researchers found that the pulverization and the degree of pulverization have a certain influence on the oil yield of white cardamom essential oil. From the analysis of the results of the orthogonal test, the factors affecting the yield of cardamom essential oil were as follows: particle size> water amount> extraction time> soaking time.
Microwave-assisted steam distillation
The essential oil of white cardamom was extracted by steam distillation and microwave-assisted steam distillation respectively, and the optimum conditions for microwave-assisted extraction of essential oil of white cardamom were determined, that is, the microwave output power was 800W, the microwave action time was 300S, and the ratio of material to liquid was 1:25. , the yield of white cardamom essential oil was 2.67%.
The highest content of white cardamom essential oil is nuclear olein. Nuclear olein accounted for 43.0% of the white cardamom essential oil obtained by steam distillation, and 50.1% of the essential oil by microwave-assisted method. And the nucleotide in Java white cardamom essential oil is 47.6% and 48.6% respectively. It can be seen that microwave-assisted extraction can increase the content of nuclear olein, the main component of essential oils.
The cardamom seed coat was extracted with petroleum ether, and the residue was further extracted with ether. Diethyl ether was removed from the extract by distillation, carbon tetrachloride was added to the residue, and the residue was heated to reflux, and then the insoluble matter was separated by centrifugation. The insoluble was then separated by a chromatographic column. The column packing is a silica gel adsorbent. The insoluble material is transferred into the chromatographic column with the mixed solution of chloroform-acetone (9:1), the column is washed with acetone, and the mixed solution of chloroform-acetone-n-hexane (8:1:1) is used as the eluent. After washing, fractions with antioxidant activity were collected. The obtained fraction was further mixed with acetone and n-hexane and extracted. The obtained mixed solution of n-hexane and acetone was cooled, and then crystals were precipitated. In addition to the above-mentioned solvents, the solvent used for extracting and washing this compound can also be ethyl acetate and ethanol as extractants, and the compound insoluble or insoluble solvent petroleum ether and chloroform can be used as eluent.
Supercritical CO2 Fluid Extraction of White Cardamom Essential Oil
The white cardamom essential oil was extracted by supercritical CO2 fluid extraction technology, and the CO2 extraction process was: the optimization single-factor operating conditions such as raw material particle size 60-80 mesh, extraction temperature 50 ℃, extraction pressure 28MPa, extraction time 2h, etc. The rate is 2.92%.
CO2 extraction methods of cardamom essential oil
CO2 extraction is a popular method for obtaining cardamom essential oil due to its ability to preserve the delicate aromatic compounds present in the plant material. Here are the two commonly used CO2 extraction methods for cardamom essential oil:
- Supercritical CO2 Extraction:
- In this method, cardamom seeds or pods are placed inside an extraction vessel.
- Supercritical CO2, which is CO2 in a supercritical state (between a gas and a liquid), is passed through the vessel at high pressure and temperature.
- The supercritical CO2 acts as a solvent and selectively extracts the essential oil compounds from the cardamom material.
- The CO2 carrying the extracted oil is then passed through a separator, where the pressure is reduced, causing the CO2 to convert back to a gas state and leaving behind the essential oil.
- The resulting oil is a highly concentrated and aromatic extract of cardamom.
- Subcritical CO2 Extraction:
- This method involves using CO2 in a subcritical state, which means it is below its critical temperature and pressure.
- Cardamom seeds or pods are placed inside an extraction vessel, similar to the supercritical extraction method.
- Subcritical CO2 is introduced into the vessel at lower temperatures and pressures compared to supercritical extraction.
- The subcritical CO2 extracts the essential oil compounds from the cardamom material, preserving the delicate aromatic profile.
- The CO2 and essential oil mixture is then depressurized, causing the CO2 to evaporate, leaving behind the essential oil extract.
Both supercritical and subcritical CO2 extraction methods offer advantages for extracting cardamom essential oil. They allow for selective extraction of the desirable aromatic compounds while minimizing thermal degradation. These methods also offer the advantage of producing high-quality essential oil without the use of harsh solvents or leaving behind residual solvent traces. The resulting cardamom essential oil is highly concentrated, aromatic, and retains the natural fragrance and therapeutic properties of the plant.
It’s important to note that the specific parameters, such as pressure, temperature, and extraction time, may vary depending on the equipment used and the desired outcome. Optimizing these parameters ensures maximum extraction efficiency and the preservation of the desired aroma and bioactive compounds in the cardamom essential oil.