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Supercritical CO2 extraction of natural plant essential oils

Natural essential oils

Supercritical CO2 extraction technology is more and more widely used in the field of natural essential oils.

Natural essential oils have a unique, natural and comfortable aroma and scent. Therefore, with the development of the food industry and people’s pursuit of naturalness and health, the scope and amount of application in food have gradually increased.

The processing and separation process of natural essential oils has always emphasized the preservation of the unique aroma of various natural essential oils, and minimize the destruction of their aroma components and the loss of trace components during the separation process, in order to prepare essential oil products with the inherent aroma of natural plants.

Extraction method of natural essential oil

The traditional extraction methods of natural essential oils include squeezing, steam distillation, solvent extraction and adsorption to make essential oils, extracts, absolutes, oleoresins and other essential oil products.

Disadventage

Due to the complex composition of natural essential oils naturally formed by plants, especially with many trace components, although the extraction technology continues to develop and improve, due to the heat treatment or solvent treatment in the processing process, the aroma of many natural essential oil products and natural aromatic plants is still There is a certain gap.

Supercritical CO2 extraction

Therefore, the use of new natural essential oil extraction and separation methods to produce essential oil products closer to the natural fragrance has become the development direction of the natural essential oil industry, and supercritical CO2 (supercritical CO2) extraction technology is the focus of research.

CO2 has become the first choice extractant in the field of supercritical extraction because of its non-toxic, odorless, non-flammable, no residue, cheap and easy-to-obtain, and suitable critical temperature and critical pressure.

Application

The application of supercritical CO2 extraction technology in the food industry mainly focuses on the extraction of natural pigments, natural essential oils, functional oils, VE and other fat-soluble substances, the separation of polar substances such as flavonoids and alkaloids, and the caffeine, heavy metals, and organic substances in agricultural products. Removal of pesticides, food sterilization and other fields, especially in the field of natural essential oil extraction, related research is extremely active.

Supercritical CO2 extraction of essential oils

Description

The non-polar substances contained in spice plants include not only volatile essential oils, but also free fatty acids, oils, waxes, resins, and pigments.

Oxygenated terpenoids

Volatile essential oils generally contain a large amount of monoterpenes, oxygen-containing terpenoids and their derivatives, small molecules of aromatic compounds, small molecules of phenolic substances, and heteroatom-containing chemical components, among which oxygen-containing terpenoids The greatest contribution to aroma is the key component of natural essential oil aroma, while monoterpenes generally contribute less to aroma.

Oleoresin

Oleoresin is the main component that affects the flavor of natural essential oils, and it is also the main component that has clinical and medical effects.

The oils and free fatty acids in some spice plants have a certain contribution to the aroma and flavor, while wax contributes little to the aroma and flavor of spice plants.

The complexity of the composition of spice plants determines that appropriate process conditions must be selected when supercritical CO2 extraction is used. According to the target requirements, comprehensive consideration of target factors such as extraction rate and product quality, the extraction of essential oil products with the best aroma or flavor.

At the same time, due to the different available parts of the spice plant, the oil storage form of the different parts is also different. For example, the oil sac of the leaf of the general spice plant is located on the surface, and the volume is also large;
The oil cells in the woody parts of spice plants are in the deep layer, and the oil cells are small and dense.

Therefore, the supercritical CO2 extraction characteristics of different plant organs are also different.

Supercritical CO2 extraction of spice plant roots, stems and bark

The available parts of many spice plants are roots, stems (rhizome) or bark. These parts are generally dense in structure, with high content of wood components such as cellulose and lignin, and high content of volatile oil and oleoresin.

Such as cinnamon and ginger

Supercritical CO2 extraction of cinnamon essential oil

Cinnamon essential oil is a volatile oil extracted from the dried bark of cinnamon. It has a strong aromatic and spicy smell.

Method of CO2 extraction

The effects of pressure, temperature, extraction time and other factors on the extraction effect of supercritical CO2 extraction of cinnamon essential oil were studied. The optimal extraction process conditions were determined through orthogonal experiments:

The extraction pressure was 15MPa, the temperature was 40℃, and the time was 2h. Under these conditions, the yield of cinnamon essential oil was 3.69%.

GC-MS was used to determine the essential oil of cinnamon extracted by supercritical CO2, and 43 components were identified, mainly including trans-cinnamaldehyde, 3-methoxycinnamaldehyde, α-propene, δ-cadinene, and α-hop Among them, trans-cinnamaldehyde has the highest content, reaching 30.97%.

Contrast

The volatile oil was extracted from cinnamon by steam distillation. The yield of cinnamon volatile oil was 1.3%, and its trans-cinnamaldehyde content was 91.67%.

The cinnamon essential oil extracted by supercritical CO2 extraction method and steam distillation method was compared, and the transfer rate of trans-cinnamaldehyde was determined. The results showed that the transfer rate of supercritical CO2 extraction method was 83.32%, and that of steam distillation method. It is 70.76%.

Ginger oil and ginger oleoresin

Ginger oil and ginger oleoresin are currently the two main deep-processed products of ginger.

Supercritical CO2 Extraction of Volatile Oil from Ginger

The extraction and separation technology of volatile oil in ginger with supercritical CO2 was studied, and the optimal process parameters were optimized by orthogonal experiment: supercritical CO2 extraction pressure was 25MPa; temperature was 45℃; time was 120min; flow rate was 25L/ min, the extraction rate of the volatile oil of ginger powder by supercritical CO2 is as high as 4.27%.

Compare

The differences between supercritical CO2 extraction and steam distillation of ginger were compared. Supercritical CO2 extraction and steam distillation were used to treat ginger respectively, and the products were analyzed and compared by GC and TLC.

The results showed that the yield of supercritical CO2 extraction product was 8.1%, and the yield of steam distillation was 0.2%. At the same time, the supercritical CO2 extraction extract had more components than the steam distillation sample.

Taking extraction rate and gingerol content as indicators, using acetone, ethanol extraction and supercritical CO2 extraction methods, the differences between supercritical extraction of ginger oleoresin and solvent extraction were compared. The results showed that the extraction rate of ethanol was 7.5167%. , The extraction rate of supercritical CO2 extraction method and acetone method is lower than that of ethanol method;

The yield of gingerol by supercritical CO2 extraction is 0.7155%, which is significantly higher than that of ethanol and acetone.

Industrialized supercritical CO2 extraction of ginger

The German Degussa company uses supercritical CO2 to extract ginger and has realized industrialization. Among them, two products, the products extracted under 10MPa contain 75% essential oil components and about 14% spice compounds (gingerol, ginger alcohol), and the products extracted under 27MPa contain 33% 35% essential oil components, about 30% spicy compounds.

Postscript

Regarding other spice plants: garlic, galangal, angelica, onion, chuanxiong, angelica, sandalwood, woody and other spice plants have research reports on supercritical CO2 extraction.

Supercritical CO2 extraction of plant seeds and fruits

Supercritical CO2 extraction of star anise

In addition to rich volatile oils and resins, the seeds and fruits of spice plants generally contain more oil components.

Take the supercritical CO2 extraction of star anise, which is more studied, as an example.

The essential oil of star anise extracted from the fruit of star anise is an important spicy essential oil.

Supercritical CO2 extraction method of star anise essential oil

Using supercritical CO2 to extract the essential oil of star anise, the best process conditions are as follows: pressure 16MPa, temperature 35℃, time 2h, CO2 flow rate 30L/h. Under these conditions, the yield of star anise extract was 10.5%.

The essential oil of star anise is extracted by steam distillation. The yield was 7.5%.

Compare

The quality and yield of essential oils obtained by two different extraction methods were compared. The yield of star anise essential oil obtained by supercritical CO2 extraction method was 40% higher than that of steam method, and the aroma was more comprehensive.

Three methods of steam distillation, organic solvent extraction and supercritical CO2 extraction were used to extract star anise oil. The gas phase spectra and chemical components of star anise oil extracted by different methods were analyzed by GC-MS.

The chemical components of the star anise oil extracted by the three methods are similar, but the steam distillation is obviously less chemical than the latter two methods. The star anise extract extracted by organic solvents and supercritical CO2 is more natural and slightly dark brown. It is viscous and has more chemical components after analysis, especially with various saturated and unsaturated fatty acids, and the flavor is richer.

In addition

In addition, there are research reports on the supercritical CO2 extraction of spice plants such as vanilla, celery seed, litsea cubeba, nutmeg, pepper, and Chinese pepper.

Supercritical CO2 extraction of plant flowers

Except for varieties such as cloves, the flowers of plants generally have low volatile oil content.

Take the supercritical CO2 extraction of roses, which has been studied more, as an example.

Rose oil is an aromatic essential oil extracted from rose flowers.

Supercritical CO2 extraction method of rose essential oil

The volatile oil components of Lengxiang rose and Sijihong rose produced in Hunchun, Jilin Province were extracted and analyzed with supercritical CO2.

The optimal extraction process was determined to be extraction pressure of 20MPa, separation pressure of 7MPa, extraction temperature of 35℃, and separation temperature of 40℃.

Supercritical CO2 extraction experiment two

Supercritical CO2 extraction technology was used to extract rose essential oil, and then molecular distillation was used to finely separate the resulting extract to obtain high-quality rose essential oil.

Supercritical CO2 extraction experiment three

Supercritical CO2 extraction technology is used to extract Pingyin rose extract in Shandong, China, and molecular distillation technology is used for refining. The yield is increased from 0.03% of traditional steam distillation to 0.1%.

Addition

In addition, the supercritical CO2 extraction of spice plants such as gardenia, hops, osmanthus, jasmine, chamomile, rose, tree orchid, lavender, etc. have all research reports.

Supercritical CO2 extraction of whole plants

There are many kinds of natural essential oils, which use the leaves of spice plants and whole herbs of herbs as raw materials, and they are used in large amounts and have a wide range of uses. Take the supercritical CO2 extraction of perilla which has been studied more as an example.

Supercritical CO2 extraction of perilla

Perilla is an annual herbaceous plant in the Lamiaceae family, containing volatile oil.

BIT studied the effect of supercritical CO2 extraction conditions on the extraction of volatile oil from perilla leaves, and determined that the best extraction conditions are extraction pressure 20MPa, temperature 45℃, CO2 flow rate 30kg/h, time 100min, and extraction rate 5.13%.

The extraction rate of volatile oil from perilla leaves by steam distillation was 0.415%.

The yield of supercritical CO2 extraction is high and the extraction time is short.

Supercritical CO2 extraction experiment two

Supercritical CO2 was used to extract the volatile oil of perilla. The volatile oil of perilla extracted under different conditions was analyzed by GC-MS and compared with the chemical components of the volatile oil obtained by steam distillation. The quality and yield are better than those obtained by distillation.

Addition

In addition, there are research reports on the supercritical CO2 extraction of spice plants such as peppermint, tea, rosemary, geraniol, lemongrass, valerian, and thyme.

Summary

Features of supercritical CO2 extraction of essential oils

Compared with traditional extraction methods, supercritical CO2 extraction technology has many advantages. For the extraction of essential oils of perfume plants, the main advantages are:

  • It can be extracted at near room temperature and under the envelope of CO2 gas, effectively preventing the oxidation and volatilization of heat-sensitive substances (such as terpenes).
  • Essential oil products have no solvent residues and are pure natural products. At the same time, they also prevent the human body from being toxic and environmental pollution during the extraction process.
  • The general yield of supercritical CO2 extraction is higher than that of traditional methods; extraction and separation are combined into one, the process flow is short, the operation is simple, and the efficiency is high; the latent heat of CO2 evaporation is low, and the energy consumption of the extraction process is low.

Comprehensive use of extraction technology to extract essential oils

Although the supercritical CO2 extraction technology has its unique advantages, as far as the extraction of essential oils of fragrance plants is concerned, because the solubility of supercritical CO2 for non-polar substances is generally high, the extraction products contain aroma and flavor components in addition to , Often contains a lot of waxes, fatty acids, etc., which affect the quality of essential oils. Therefore, for spice plants with complex ingredients, supercritical CO2 extraction technology is often required in combination with other separation methods.

Four suggestions

Four suggestions for supercritical CO2 extraction of plant essential oils

  • Supercritical CO2 extraction of natural essential oil products should be products that are difficult to produce by traditional methods, such as the extraction of some fresh flower top notes.
  • The selection of supercritical CO2 extraction of natural essential oil products should significantly improve the quality of traditional products, such as the extraction of plants containing polyphenols such as tea.
  • Supercritical CO2 extraction of natural essential oil products should have no obvious disadvantages compared with traditional products, such as vanilla and other raw materials with higher value and extraction rate.
  • The specifications of the supercritical CO2 industrial extraction equipment should not be too large. Because of the large variety of natural essential oils and the small demand, it is advisable to use a set of equipment to extract a variety of essential oils.

200L CBD oil supercritical CO2 extraction equipment
200L CBD oil supercritical CO2 extraction equipment

Special vegetable oils approved by China in 2008

VarietyExtraction methodTraits
Tomato seed oilSqueezing method, supercritical CO2 method, extraction method, fluid extraction method, etc.Light yellow to orange oily liquid
Silybum marianum seed oilSqueezing method, water generation method, solvent extraction method, water enzymatic method, microwave method, supercritical CO2 method, etc.Light yellow transparent oily liquid
Almond OilExtraction method, low temperature pressing methodYellow transparent oily liquid
Light Bark Fruit OilLow-temperature squeezing-butanol extraction, supercritical CO2 method, microwave sound assisted method, water enzymatic methodYellow transparent oily liquid
Suaeda salsa seed oilSolvent extraction method, microwave assisted extraction, supercritical CO2 methodLight yellow to golden yellow transparent oily liquid
Miteng Fruit OilCold pressing, supercritical extraction, Soxhlet extractionLight yellow transparent oily liquid
Salt skin tree fruit oilUltrasonic extraction, Soxhlet extractionLight yellow transparent oily liquid
Acer truncatum seed oilSolvent extraction, mechanical oil extractionGolden yellow transparent oily liquid
Peony seed oilPressing method, leaching method, reverse micellar extraction method, super-pro CO2 method, water generation method, water enzymatic method, extraction method, microwave extraction method, etc.Golden yellow transparent oily liquid
Eucommia Samara OilWater enzymatic method, solvent method, supercritical CO2 method, etc.Light yellow transparent oily liquid
Poppy seed oilCold pressing method, water substitution method, solvent extraction methodLight yellow semi-permeable oily liquid
Tea seed oilSupercritical CO2 method, microwave-assisted water generation method, water enzymatic method, pressing method, cold pressing method and organic solvent extraction method, etc.Yellow transparent oily liquid
Eucommia oilseedSqueezing method, solvent extraction method, supercritical CO2 method, consciousness extraction, water extraction method, Soxhlet extraction method, microwave assisted extraction method, etc.Yellow transparent oily liquid

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