Design

Methods for obtaining essential oils of plants. Methods for obtaining essential oils

Olga Petrashchuk, candidate of biological sciences, teacher of the international school MegaSPA.

The essential oil flora includes more than 2000 species of plants, of which about 1000 grow in our country, but only 150-200 species are of industrial importance. Most essential oils are obtained from tropical or subtropical plants, and only a few (coriander, anise, mint, etc.) are cultivated in more temperate latitudes (organic or conventional cultivation). Particularly rich in oils are numerous species of the labiaceae family (mint, lavender, sage, basil, patchouli, etc.), umbellate (anise, fennel, cumin, coriander, ajgon, etc.), rosaceae (essential oil rose), geraniums (pink geranium); amaryllis (tuberose), myrtle (lemon eucalyptus), etc.

Oils are named, as a rule, according to the types of plants from which they are obtained (pink, geranium, lavender), less often - according to the main component (camphor, eugenol, turpentine).

Raw materials for the extraction of oils are used either raw (geranium green mass, lavender flowers, etc.), dried (mint), dried (calamus roots, iris, etc.), or pre-fermented (rose flowers, oak moss). In plants such as bitter almond, cucumber, horseradish or mustard, aromatic substances are contained in a bound form. To release them, it is necessary to destroy the cellular structure of these plants and only then extract the aromatic substances.

Extraction of essential oils from plants

In the XI century, Avicenna described a method for obtaining essential oils by distillation, known to the Arabs from the VIII-IX centuries. Prior to this, ancient civilizations for many hundreds of years used extracts of fragrant flowers, herbs and roots, infused in vegetable oils or melted solid fats (maceration).

Nowadays, chemists use a rich set of methods to extract essential oils from plants. Depending on the form it is in essential oil in the plant (in the free and/or bound state), various extraction methods are used or combinations are used various ways. The free form makes it possible to extract essential oils by steam distillation, air stripping, pressing or solvent extraction (volatile and non-volatile). Extraction of bound forms of essential oils requires prior release of the essential oil via fermentation (enzymatic hydrolysis).

Fermentation consists in maintaining the feedstock from several hours to a day at a temperature of 50-600C. Due to the breakdown of glycosides under the action of the plant's own enzymes, a significant amount of essential oils is formed, which can be extracted various methods. A type of fermentation can be long-term storage(2-3 years) of iris roots in dry conditions, after which the necessary aromatic components accumulate in them. After fermentation, essential oils are distilled off as a free form. Hydrolytic processes can also occur during steam distillation. In some cases, before steam distillation, the raw materials are kept in salt solutions with a concentration of 5-20%. In this case, the essential oil is released from plant cells as a result of the so-called osmotic shock, that is, the destruction of cells under the action of salt.

Obtaining essential oils by steam distillation

Steam distillation is most often used when the plant contains a lot of essential oils. In addition, in some cases, only steam distillation makes it possible to obtain essential oils of a certain quality, for example, those containing azulenes (chamomile, yarrow). Steam distillation is carried out both by distillation of a mixture of raw materials and water (hydrodistillation), and by the direct effect of steam on the raw materials (steam distillation).

hydrodistillation. The simplest option is to distill the water in the presence of plant material. It is used quite rarely, for example, when obtaining rose oil. Used in laboratory conditions. Depending on the pressure, hydrodistillation is carried out at normal pressure (most often) or in vacuum (vacuum hydrodistillation - distillation with steam at reduced pressure). There are proposals to carry out hydrodistillation at elevated pressures up to several atmospheres, which significantly improves the ratio of water in the distillate to the substance distilled off with it. The increased temperature required to boil water promotes faster distillation. The oil isolated in this way differs somewhat from the performance of the oil isolated in the traditional way.

Steam distillation. The most economical and technologically convenient way stripping is to use superheated steam (high pressure steam). At the same time, it is possible to avoid local overheating of the plant material that occurs during hydrodistillation and to drive off the hardly volatile, often very valuable components of the essential oil. By this method, the predominant amount of commercial essential oil is obtained.

The resulting vapor carries with it the volatile components of the essential oil. Then, the steam is cooled with running water, and the liquid mixture of water and essential oil is stratified in the receiver. The device of the receiver depends on the specific gravity of the oil. If the oil is lighter than water, it floats up and the water is removed through the side tube. If the oil is heavier, then it collects at the bottom of the receiver, and excess water is drained through the hole in the top. Both designs are varieties of the so-called Florentine flask. The oil obtained by distillation with steam is called distillation oil.

Some essential oils are partially soluble in water and during distillation with steam, some of them are carried away in dissolved form with distillation waters. Oils containing phenols and terpene alcohols have the highest solubility, esters have the lowest solubility, and terpene hydrocarbons are practically insoluble. With the simultaneous content of both highly soluble and slightly soluble components, phenols and terpene alcohols are washed out of the resulting essential oil. With economic and technological need, this part of the essential oil can be isolated and used. The separation of the soluble components of the essential oil from the distillate is called cobation. Usually cobation essential oil is added to distillation oil to increase the overall yield. However, such a technological operation requires great care not to spoil the primary oil.

In some cases, a low yield of oil allows only aromatic water to be obtained from the plant in the process of water distillation. Then it is used as a toilet. The water that remains from the distillation process is called hydrosol. Hydrosols contain a wide range of water-soluble components of essential oils. In addition to carboxylic acids, hydrosols contain a large amount of terpene and sesquiterpene alcohols, which makes it possible to use them as skin care products (rose, chamomile, St. John's wort, myrtle). Hydrosols are also an excellent source of valuable alcohols that do not have the irritating effect that terpene hydrocarbons do. However, chemical changes easily occur in hydrosols, as well as changes associated with the active actions of microorganisms. To preserve the composition of hydrosols, preservatives are added to them.

A number of essential oils can only be obtained by steam distillation (certain types of chamomile and yarrow). The fact is that in a bound (non-volatile form) the plant contains substances belonging to the class of sesquiterpene lactones. During the decomposition of these lactones, as a result of hydrolysis with water vapor, an important class of components of essential oils is formed - azulene. These substances color essential oils in a deep blue and green color and give them special physiologically active properties (anti-inflammatory, anti-burn).

Destructive distillation. Sometimes, to obtain essential oil, various woody materials (birch, juniper) are heated in a vacuum. At the same time, the aroma components disappear, part of the wood is destroyed and a number of phenolic compounds are formed, which give the resulting essential oil the smell of “tanned leather”. This essential oil has healing properties, it is also used in perfumery in the manufacture of perfumes for men.

A special, very important class of aromatic plant secretions are balms. Balms are obtained from resinous secretions on the bark of some shrubs and trees. These secretions are formed at the site of natural (pests) or artificial (cuts or burns) damage to the surface of the bark. The released resin, at first liquid, eventually hardens and turns into balsamic resins or balms. The composition of balms includes a certain amount of volatile substances (5-60%), the components of which have a smell and determine the aroma of balms. Balsams are steam distilled to produce essential oils that are of some value in perfumery.

Obtaining essential oils by extraction with volatile solvents

For many very important aromatic plants (rose, jasmine, mignonette, narcissus and jonquilla, violet, heliotrope, levkoy, frankincense, hyacinth, lilac), steam distillation does not work at all or leads to an oil completely unusable. In this case, extraction with volatile organic solvents is used. The most commonly used solvents are ethyl alcohol and purified petroleum ether. The use of other solvents (chloroform, ethyl ether, benzene) is often economically disadvantageous, since these solvents are relatively expensive, in addition, their use leads to the production of strongly colored preparations.

The extraction process consists of two stages: the actual extraction of the components from the plant material and the removal of the solvent (often under reduced pressure). After being freed from the solvent, a semi-liquid or solid mass of dark color is obtained, which is called "concrete". Along with volatile aromatic compounds, it contains a lot of non-volatile components (paraffins, wax, esters of higher fatty acids and resins). The content of essential oil in concrete is 5-20%. From concrete, these essential oils are most often extracted with ethyl alcohol. To do this, the concrete is dissolved in alcohol. In this case, 20-60% of the concrete passes into the solution. Insoluble substances are filtered off under strong cooling to separate from the waxes, and alcohol solution decolorize with activated charcoal and evaporate in vacuo. At the same time, an absolute oil (“absolute”) is obtained, which is extremely valued in perfumery.

Liquefied gases (carbon dioxide and freons) are also used for extraction. They allow the process of extraction and obtaining concrete much more efficiently, but this requires a lot of preparatory work with raw materials, often incompatible with maintaining its perfume quality. In the case of spicy-aromatic raw materials, the use of CO2-extraction is the most promising. The extracts retain a bright aroma, taste and biologically valuable components inherent in plants (group E vitamins, di- and triterpenes). They are sterile and have antioxidant properties. The conditions for extracting concentrates from fresh fruits (apples, pears, oranges), spices (black pepper, cloves, cinnamon) and aromatic plants (calamus, cardamom, marjoram) have been selected. The resulting extracts, in addition to the essential oil, also contain a large amount (10-90%) of fatty oil. In some cases, this has a positive value, since the fat part, in combination with the aromatic component, is a good biologically active complex suitable for use in cosmetic products. For use in perfumery preparations, this combination is unacceptable, since the extracts must be dissolved in alcohol, while the fat base, which is insoluble in alcohol, will precipitate.

Maceration and enfleurage. Varieties of the extraction method for extracting essential oil are quite rare methods of maceration and enfleurage. These methods consist in the absorption of volatile aromatic compounds of flowering plants by non-volatile solvents.

Maceration is that the flower petals in bags for some time (up to 2 days) are immersed in animal fat or vegetable oil heated to 50-700, purified by a special method. After a multiple (20-25 times) change of raw materials, a sufficient amount of aromatic substances accumulates in the fat (oil).

Enfleurage consists in the absorption of essential oils of flowers on special frames covered with a layer of fat or fabric soaked in vegetable oil. After 72 hours, the flowers are removed and replaced with new ones, repeating the process up to 30 times. The product obtained in the process of maceration and enfleurage is called flower lipstick (if the extraction was carried out with fat) or antique (incense) oil (if the extraction was carried out with vegetable oil). It is treated with alcohol to extract aromatic components and the resulting concentrate is used as a high-quality perfume raw material.

modern and in a technological way extraction of essential oils of some flowering plants (jasmine) is dynamic adsorption, that is, the absorption of aromatic substances by activated carbon or other solid adsorbents. To do this, flower petals are loaded into the chamber and blown with humidified air. The air saturated with aromas is sent to the activated carbon adsorber, where the coal is saturated with essential oil. The charcoal is then washed with diethyl ether and the ether is evaporated. Most often, the resulting extract is added to the absolute, obtained in the usual way from the concrete. Sometimes, for a more complete extraction of essential oils after adsorption methods, the raw materials are subjected to steam distillation.

Obtaining essential oils by pressing

In some cases (especially in the case of citrus fruits) it is possible and economically profitable to obtain oil by simply pressing the raw material. To do this, the peel or whole fruits are pressed, and the released emulsion of essential oil in juice is centrifuged. In this case, the oil is on top and it is separated.

The disadvantage of citrus oils obtained by pressing is the admixture of phototoxins contained in them. These substances, when applied to the skin, activate sunlight, which leads to skin burns. To prevent this phenomenon, phototoxins are removed chemically. The resulting oil, tested on biological objects, is no longer toxic and safe to use.

After pressing, up to 30% of the essential oil remains in the raw material, which is separated by steam distillation. The additional distillation oil obtained has an inferior aromatic quality, but is sufficient for use as a deodorant. His good quality is that it does not contain phototoxins.

The International Organization for Standardization ISO (ISO) defines essential oils as follows:

100% natural (natural) means that the oil essence does not contain any synthetic additives, emulsifying agents, mineral oils, etc.
100% Pure - No other oil essences have been added to this product. If it is lavender oil, then no other types of lavender oil (such as lavandin) have been added to it.
100% complete (complete) means that this oil essence has not passed special treatment, terpenes have not been removed from it, or the oil essence has not been properly purified, etc.

The chemical composition of an essential oil can vary. The amount of each component can vary widely even for one type of plant, which depends on the place where the plant is grown, the period of harvesting of raw materials and the stage of vegetation, the duration and conditions of storage of raw materials, as well as the technology of its processing. This makes it difficult to standardize essential oils. The International Organization for Standardization ISO (ISO) has established a gas-liquid chromatography (reference) profile for each essential oil, which makes it possible to evaluate the quality of the resulting essential oil.

The high cost of essential oils often provokes their falsification. The most common methods of falsification:

dilution of essential oil with vegetable;
diluting an expensive essential oil with a cheap one (for example, peppermint oil with field mint oil);
dilution of one essential oil with natural components of another (for example, lemon with orange terpenes);
adding synthetic substances to the oil (for example, synthetic linalool to neroli oil).

In the process of using essential oils in aromatherapy, there are many problems associated with their safety. These problems are also associated with the peculiarities of the relationship to essential oils as substances of natural origin. It is assumed that natural substances are quite compatible with the human body and cannot have a harmful effect. At the same time, they forget that they are found in nature in negligible concentrations, and essential oils are highly concentrated mixtures of plant aromas. The degree of concentration in relation to their content in plants is 50-1000 times. If we talk about the content of essential oils in the air, then the degree of concentration of the components of the essential oil reaches several million times. Therefore, the use of essential oils when applied to the skin should be limited in most cases to dilute solutions, usually in ethyl alcohol or fats (vegetable oils). Such solvents of essential oils are called "carriers". Solvents used to dilute essential oils must be chemically stable and free from foreign or unpleasant odors. Used as natural carriers vegetable oils and waxes. The concentration of essential oils recommended in aromatherapy should not exceed 25%; in cosmetic preparations, 5-10% of essential oils are usually used: 1% for dry and sensitive skin; 2% for normal, oily and combination skin; 4% and above - in the form of a concentrate for a pronounced therapeutic effect on the skin.

Aromatherapy is not only the art of managing emotions and the science of health promotion, it is also knowledge about the technologies for obtaining essential oils - both ancient and modern. What factors influence the quality of the final product? What must be remembered in order to choose the right aromatic compounds for certain purposes?

The essential oil flora includes more than 2000 species of plants, of which about 1000 grow in our country, but only 150 ... 200 species are of industrial importance. Most essential oils are obtained from tropical or subtropical plants, and only a few plants (coriander, anise, mint, etc.) are cultivated in more temperate latitudes (organically or conventionally). Particularly rich in oils are numerous species of the labiaceae family (mint, lavender, sage, basil, patchouli, etc.), umbellate (anise, fennel, cumin, coriander, ajgon, etc.), rosaceae (essential oil rose), geraniums (pink geranium); amaryllis (tuberose), myrtle (lemon eucalyptus), etc.

Unlike vegetable oils, essential oils are multicomponent mixtures of volatile organic compounds (aromatic, alicyclic and aliphatic carbonyl compounds, alcohols, acids, esters, etc.) produced in special cells of various plants and causing their smell. Essential oils in the free state or in the form of glycosides are found in leaves, stems, roots, seeds, fruits, bark and wood. The content of oils in plants varies widely: for example, in rose flowers they contain 0.02 ... 0.10%, and in clove buds - 20 ... 22%, but the largest amount accumulates in most plants during flowering and seed ripening. Oils are named, as a rule, according to the types of plants from which they are obtained (pink, geranium, lavender), less often - according to the main component (camphor, eugenol, turpentine). Raw materials for the extraction of oils are used either raw (geranium green mass, lavender flowers, etc.), dried (mint), dried (calamus roots, iris, etc.), or pre-fermented (rose flowers, oak moss). In plants such as bitter almond, cucumber, horseradish or mustard, aromatic substances are contained in a bound form; to release them, it is necessary to destroy the cellular structure of these plants.

Extraction of essential oils from plants

In the 11th century, Avicenna described a method for obtaining essential oils by distillation, known to the Arabs from the 8th-9th centuries. Prior to this, ancient civilizations for many hundreds of years used extracts of fragrant flowers, herbs and roots, infused in vegetable oils or melted solid fats (maceration).

Nowadays, chemists use a rich set of methods to extract essential oils. from plants: depending on the form in which the essential oil is found (in the free and / or bound state), different extraction methods are used or combinations of different methods are used. The free form makes it possible to extract essential oils by steam distillation, air stripping, pressing or extraction with solvents (volatile and non-volatile). To extract the bound forms of essential oils, they must first be released by fermentation (enzymatic hydrolysis).

Fermentation consists in maintaining the feedstock from several hours to a day at a temperature of 50 ... 60 ° C. Due to the breakdown of glycosides under the action of the plant's own enzymes, a significant amount of essential oils is formed, which can be extracted by various methods. A variation of fermentation can be long-term storage (2-3 years) of iris roots in dry conditions, after which the necessary aromatic components accumulate in them. After fermentation, essential oils are distilled off as a free form. Hydrolytic processes can also occur during steam distillation. In some cases, before steam distillation, the raw material is kept in salt solutions with a concentration of 5 ... 20%. In this case, the essential oil is released from plant cells as a result of the so-called osmotic shock, that is, the destruction of cells under the action of salt.

Steam distillation

Steam distillation is most often used when the plant contains a lot of essential oil. In addition, in some cases, only this method allows you to get essential oils of a certain quality, for example, those containing azulene (chamomile, yarrow). Steam distillation is carried out both by distillation of a mixture of raw materials and water (hydrodistillation), and by the direct effect of steam on the raw materials (steam distillation).

Hydrodistillation. The simplest option is to distill the water in the presence of plant material. It is used quite rarely, for example, when obtaining rose oil. Used in laboratory conditions. Depending on the pressure, hydrodistillation is carried out at normal pressure (most often) or in vacuum (vacuum hydrodistillation - distillation with steam at reduced pressure). There are proposals to carry out hydrodistillation at elevated pressures up to several atmospheres, which significantly improves the ratio of water in the distillate to the substance distilled off with it. The increased temperature required to boil water promotes faster distillation. The oil isolated in this way is somewhat different from the oil isolated in the traditional way.

Steam distillation. The most economical and technologically convenient way of distillation is to use superheated steam (high pressure steam). At the same time, it is possible to avoid local overheating of the plant material that occurs during hydrodistillation, and to drive off the hardly volatile, often very valuable components of the essential oil. By this method, the predominant amount of commercial essential oil is obtained.

The resulting vapor carries with it the volatile components of the essential oil. Then the steam is cooled with running water, and the liquid mixture of water and essential oil is stratified in the receiver. The device of the receiver depends on the specific gravity of the oil. If the oil is lighter than water, it floats up and the water is removed through the side tube. If the oil is heavier, then it collects at the bottom of the receiver, and excess water is drained through the hole in the top. Both designs are varieties of the so-called Florentine flask. The oil obtained by distillation with steam is called distillation oil.

Some essential oils are partially soluble in water and during distillation with steam, some of them are carried away in dissolved form with distillation waters. Oils containing phenols and terpene alcohols have the highest solubility, ethers have the lowest solubility, and terpene hydrocarbons are practically insoluble. With the simultaneous content of highly soluble and slightly soluble components, phenols and terpene alcohols are washed out of the resulting essential oil. With economic and technological need, this part of the essential oil can be isolated and used. The separation of the soluble components of the essential oil from the distillate is called cobation. Usually cobation essential oil is added to distillation oil to increase the overall yield. However, such a technological operation requires great care not to spoil the primary oil.

In some cases, a low yield of oil allows only aromatic water to be obtained from the plant in the process of water distillation. Then it is used as a toilet. The water that remains from the distillation process is called hydrosol. Hydrosols contain a wide range of water-soluble components of essential oils. In addition to carboxylic acids, hydrosols contain a large amount of terpene and sesquiterpene alcohols, which makes it possible to use them as skin care products (rose, chamomile, St. John's wort, myrtle). Hydrosols are also an excellent source of valuable alcohols that do not have the irritating effect of terpene hydrocarbons. However, chemical changes easily occur in hydrosols, as well as changes associated with the active actions of microorganisms. To preserve the composition of hydrosols, preservatives are added to them.

A number of essential oils can only be obtained by steam distillation (from certain types of chamomile and yarrow). The fact is that in a bound (non-volatile form) the plant contains substances belonging to the class of sesquiterpene lactones. During the decomposition of these lactones, as a result of hydrolysis with water vapor, an important class of components of essential oils is formed - azulene. These substances color essential oils in a deep blue and green color and give them special physiologically active properties (anti-inflammatory, anti-burn).

destructive distillation. Sometimes, to obtain essential oil, various woody materials (birch, juniper) are heated in a vacuum. At the same time, the aroma components disappear, part of the wood is destroyed, and a number of phenolic compounds are formed, which give the resulting essential oil the smell of "tanned leather". This essential oil has a number of healing properties, it is also used in perfumery in the manufacture of perfumes for men.

A special, very important class of aromatic plant secretions are balms. They are obtained from the resinous secretions on the bark of some shrubs and trees. These secretions are formed at the site of damage to the surface of the bark, natural (by pests) or artificial (cuts or burns). The released resin, at first liquid, eventually hardens and turns into balsamic resins or balms. The composition of balms includes a certain amount of volatile substances (5 ... 60%), the components of which have a smell and determine the aroma of balms. By distillation of balms with water vapor, essential oils are obtained, which are of some value for perfumery.

Extraction with volatile solvents

Steam distillation of many very important aromatic plants (rose, jasmine, mignonette, narcissus, violet, heliotrope, levkoy, hyacinth, lilac, etc.) does not give any result at all or leads to an oil that is completely unsuitable for use. In this case, extraction with volatile organic solvents is used. The most commonly used solvents are ethyl alcohol and purified petroleum ether. Other solvents (chloroform, ethyl ether, benzene) are relatively expensive, in addition, their use leads to the production of strongly colored preparations.

The extraction process consists of two stages: the actual extraction of the components from the plant material and the removal of the solvent (often under reduced pressure). After being freed from the solvent, a semi-liquid or solid mass of dark color is obtained, which is called "concrete". Along with volatile aromatic compounds, it contains a lot of non-volatile components (paraffins, wax, esters of higher fatty acids and resins). Essential oils contained in concrete (their 5 ... 20%) are most often extracted with ethyl alcohol, while 20 ... 60% of concrete passes into the solution. The undissolved substances are filtered off under strong cooling to separate from the waxes, and the alcoholic solution is decolorized with activated carbon and evaporated in vacuo. At the same time, an absolute oil (absolute) is obtained, which is extremely valued in perfumery.

Liquefied gases (carbon dioxide and freons) are also used for extraction. They allow the extraction process and concrete production to be carried out much more efficiently, but this requires a large preparatory work with raw materials, often incompatible with the preservation of its perfume quality. In the case of spicy-aromatic raw materials, the use of CO2-extraction is the most promising: extracts retain a bright aroma, taste, and biologically valuable components inherent in plants (group E vitamins, di- and triterpenes). They are sterile and have antioxidant properties. The conditions for isolating concentrates from fresh fruits (apples, pears, oranges), spices (black pepper, cloves, cinnamon) and aromatic herbs (calamus, cardamom, marjoram) have been selected. The obtained extracts, in addition to the essential oil, also contain a large amount (10...90%) of fatty oil. In some cases, this has a positive value, since the fat part, in combination with the aromatic component, is a good biologically active complex suitable for use in cosmetic products. For use in perfume preparations, this combination is unacceptable, since the extracts must be dissolved in alcohol, while the fat base, which is insoluble in alcohol, will precipitate.

Maceration and enfleurage. Varieties of the extraction method for extracting essential oil are quite rare methods of maceration and enfleurage. They consist in the absorption of volatile aromatic compounds of flowering plants by non-volatile solvents.

During maceration, flower petals in bags for some time (up to 2 days) are immersed in animal fat or vegetable oil heated to 50-70 °, purified by a special method. After a multiple (20-25 times) change of raw materials, a sufficient amount of aromatic substances accumulates in the fat (oil).

Enfleurage consists in absorbing the essential oils of flowers on special frames covered with a layer of fat or cloth soaked in vegetable oil. After 72 hours, the flowers are removed and replaced with new ones, repeating the process up to 30 times. The product obtained in the process of maceration and enfleurage is called flower lipstick (if the extraction was carried out with fat) or antique (incense) oil (if the extraction was carried out with vegetable oil). It is treated with alcohol to extract aromatic components and the resulting concentrate is used as a high-quality perfume raw material.

A modern and technological way to extract the essential oils of some flowering plants (jasmine) is dynamic adsorption, that is, the absorption of aromatic substances with activated carbon or other solid adsorbents. To do this, flower petals are loaded into the chamber and blown with humidified air. The air saturated with aromas is sent to the activated carbon adsorber, where the coal is saturated with essential oil. The charcoal is then washed with diethyl ether and the ether is evaporated. Most often, the resulting extract is added to the absolute, obtained in the usual way from the concrete. Sometimes, for a more complete extraction of essential oils after adsorption methods, the raw materials are subjected to steam distillation.

Pressing

In some cases (especially with citrus fruits) it is possible and economically profitable to obtain oil by simply pressing raw materials. To do this, the peel or whole fruits are pressed, and the released emulsion of essential oil in juice is centrifuged. In this case, the oil is on top, and it is separated.

The disadvantage of pressed citrus oils is the admixture of phototoxins contained in them: these substances, when applied to the skin, activate sunlight, which leads to burns. To prevent this phenomenon, phototoxins are removed chemically. The resulting biologically tested oil is already non-toxic and safe to use.

After pressing, up to 30% of the essential oil remains in the raw material, which is separated by steam distillation. The aromatic quality of the additional distillation oil obtained is worse, but it is sufficient for use in deodorants. Its important property is the absence of phototoxins.

The greatest amount of oil accumulates in plants at the time of flowering and seed maturation.

About International Standards

The International Organization for Standardization ISO (ISO) defines essential oils as follows:

100% natural (natural) - oil essence does not contain any synthetic additives, emulsifying agents, mineral oils, etc.;

100% pure (pure) - no other oil essences have been added to this product: if this is lavender oil, then no other types of lavender oil (for example, lavandin) have been added to it;

100% complete (complete) - the oil essence has not been specially processed, terpenes have not been removed from it, or the oil essence has not been subjected to appropriate purification, etc.

The chemical composition of an essential oil can vary. The amount of each component can vary widely even for one type of plant: it all depends on the place of cultivation, the period of harvesting of raw materials and the stage of vegetation, the duration and conditions of storage of raw materials, as well as the technology of its processing. This makes it difficult to standardize essential oils. However, ISO has established a gas-liquid chromatography (reference) profile for each essential oil, which allows their quality to be judged. The high cost of essential oils often provokes their falsification. The most common methods of falsification:

Dilution of essential oil with vegetable;

Dilution of an expensive essential oil with a cheap one (for example, peppermint oil with field mint oil);

Dilution of one essential oil with natural components of another (for example, lemon - orange terpenes);

Addition of synthetic substances to the oil (for example, synthetic linalool to neroli oil).

In the process of aromatherapy, there are many problems associated with the safety of using essential oils. It is assumed that natural substances are quite compatible with the human body and cannot have a harmful effect. At the same time, it is forgotten that in nature they are found in negligible concentrations, and essential oils are highly concentrated mixtures of plant aromas. Their content in essential oils is 50-1000 times higher than the concentration in plants. Therefore, the use of essential oils when applied to the skin should be limited in most cases to dilute solutions, usually in ethyl alcohol or fats (vegetable oils). Such solvents of essential oils are called "carriers". Solvents used to dilute essential oils must be chemically stable and free of foreign or offensive odors. Vegetable oils and waxes are used as natural carriers. The concentration of essential oils recommended in aromatherapy should not exceed 25%; in cosmetic preparations, 5 ... 10% of essential oils are usually used: 1% - for dry and sensitive skin; 2% - for normal, oily and combination skin; 4% and above - in the form of a concentrate for a pronounced therapeutic effect on the skin.

Methods for obtaining essential oils. Production. Methods for obtaining essential oils. Vegetable raw materials. Ferry transfer. Deterpenization. aaPressing. Maceration. Enfleurage. Aroma extraction.

Production of essential oils.

The technology for the production of essential oils only at first glance seems simple. It has its own secrets and nuances. Each plant needs its own method of extracting aroma, followed by purification from hydrocarbons - deterpenization.
Deterpenization*- separation of hydrocarbons - terpenes and sesquiterpenes, easily oxidized in air, especially in the light, components of essential oils (having high bactericidal activity), resulting in saturation (due to thickening) of the oil with oxygen-containing components.

Distillation*- this is the most old way obtaining essential oils from plant materials. per day and - this is the steam distillation of volatile fractions of vegetable raw materials along the coil through filters. In this production method, it is very importantn selection of the optimal steam temperature, since intensive heat treatment increases the yield of essential oil at the expense of its quality.

Important! Therefore, essential oils domestic production often do not meet international standards.

Method 1. Distillation with water.

The method of distillation of essential oil with water from plant materials is based on the physical law partial* Dalton-Raoult pressure. The essence of the method is based on the fact that two immiscible liquids heated together boil at a temperature below the boiling point of each liquid separately, which is very important, since this does not affect the therapeutic properties of the essential oil, as well as their evaporation rate and practical insolubility. in water. Water vapor from the steam generator passes through the plant material, extracting the volatile substances of essential oils, which are then condensed in coolers and gradually collected in the receiver.

Partial* —(Latin - partiaiis- partial — part- part) - the pressure of a single component of the gas mixture.

The boiling point of the individual components of essential oils ranges from 150 to 350 °C.For example, the boiling point for

pinene - 160°C,
limonene - 177°C,
geraniol - 229°C,
thymol - 233°C.

However, all these substances, as essential oil components, are distilled in the presence of water vapor at temperatures below 100°C. Thus, a mixture of turpentine and water at atmospheric pressure will distill at 95.5°C (instead of 160°C for pinene, the main component of turpentine). Therefore, under these conditions, the partial* vapor pressure of the mixture reaches atmospheric pressure (boiling condition) even before the water boils. This method requires less complex equipment, but gives a lower oil yield, the quality of which can be reduced due to overheating of the raw material.

Method 2: Steam distillation.

Steam distillation- is the most common industrial way for the production of essential oils, it is intended primarily for use in medical practice, as well as in the perfumery and food industries.

The method of distillation of essential oil with water vapor from vegetable raw materials is also based on the physical law of the partial pressure of Dalton-Renier. It is used in cases where the content of essential oil in the raw material is quite high, and the distillation temperature (about 100 ° C) does not affect its quality. Steam distillation is carried out in pot stills or in continuously operating stills.

Stills are intermittent installations consisting of

distillation cube,
capacitor
and receiver.

Cube has a double jacket in which steam circulates, protecting the cube from cooling. At the bottom of the cube there is a perforated coil, through which steam enters for oil distillation.

The cube is closed with a lid, which is connected to the capacitor.

receiver serve the so-called Florentine flasks with drain tubes. They are designed so that if the oil lighter than water, then it is collected in a layer from above, while the water flows out through the drain tube, which is fixed in a tube at the bottom of the bottle. If the essential oil heavier than water then it sinks to the bottom, and the water is removed through a tube fixed at the top of the bottle.

Raw material loaded into a cube on a false bottom. Through the valve and the coil, steam is let into the cube, which, passing through the plant mass, carries with it the essential oil. In cases where running waters contain a lot of valuable essential oil in a dissolved or emulsified state (for example, when receiving rose oil), it is separated by secondary distillation of distant waters. At the same time, most of the retained oil is distilled off with the first portions of water.

For recycling large quantities raw materials are used continuously operating distillation apparatus. Steam distillation can be carried out not only with atmospheric pressure, but also under pressure with superheated steam. In this case, the ratio of water and essential oil favorably changes in favor of an increase in the distilled oil. This is explained by the fact that the decrease in the elasticity of water vapor is disproportionate to the change in the elasticity of the vapor of the essential oil.

Distillation under reduced pressure allows you to lower the temperature of distillation and thereby keep the constituents of essential oils intact. In all cases of distillation of essential oils with water vapor, a distillate is obtained, which is collected in a receiver and settled. Essential oils with a density less than one are collected in the upper part of the receiver above the water. In the case of distillation of essential oils with a density greater than one, they are collected under water.

Essential oils are distilled from both fresh and dried raw materials. However, not all types of essential oil plants can be dried, some of them etc.) require fresh distillation, since drying of raw materials of these types leads to significant losses of essential oil and, consequently, to a decrease in its yield during steam distillation.

In order to increase the yield of essential oil from vegetable raw materials, the so-called salting out method is used, that is, adding any salt (sodium chloride, etc.) to distillation waters. In this case, salt displaces droplets of essential oil from the intermolecular space of the solvent (water). In order to completely extract the essential oil from the distillate, the latter is treated with a low-boiling organic solvent (hexane, diethyl ether) and, after removing the solvent, an essential oil is obtained.

Popular books by some domestic authors describe a method for separating terpene hydrocarbons by vacuum distillation with water vapor (vacuum rectification), but this method does not always give nice results- with it, many other valuable components of essential oils also pass into distillation, in addition, during rectification, gumming or decomposition of valuable components of oils can occur. In this regard, this method is of limited use for a narrow range of essential oils. Some methods for separating terpene hydrocarbons are given according to L. Yu. Bryusova (1947):

Method 3. Cold pressing.

This method is used in the production of essential oils from citrus fruits.

Centrifugation obtained by cold pressing aromatic substances with subsequent filtration. The method is used mainly for fruit and peel essential oils and is the cheapest, especially if you "save" on deterpenization (rectification and freezing).

). This is due to the fact that essential oils are localized in large receptacles of the peel of fruits, which makes it possible to obtain them by pressing. Pressing is carried out on hydraulic presses, acting on the peel remaining after squeezing the juice from the fruit. To do this, the peel is first passed through toothed rollers. The essential oil remaining (up to 30%) in the peel is further extracted by distillation.

Previously, the peel of the fruit was pressed by hand.

Method 4. Maceration or enfleurage.

Enfleurage- this is the absorption (absorption) of aromatic substances from the plant. It is applied to petals, thin leaves, inflorescences and roots). In ancient times, the procedure looked very simple. The silk fabric was stretched over the frames, then soaked in fat. Then raw materials were applied to it and the fat impregnated with aroma was scraped off after a while and an aromatic lipstick was obtained, which was then subjected to extraction. The solution was freed from impurities (alcohol, fats), obtaining an absolute essential oil or absolute.

Oils obtained by maceration* are tuberose, jasmine, verbena, vanilla, orris root, rose, mimosa, violet root, narcissus… As a rule, they have a very high cost.

Maceration*- (Latin - maceratio, macero- soften, soak) - this is the extraction of essential oil by sorbents by dissolving and absorbing volatile substances. It can be carried out, for example, with fat.

Cold or warm extraction essential oils from plants with alcohols, ethers, butane, followed by purification from the solvent.

The method is based on the fact that the essential oil released from the collected raw materials absorbed by sorbents (solid fats, activated carbon, etc.). This process is carried out in special frames, hermetically assembled 30-40 pieces (one on top of the other) into a battery. When working with solid fats, a fat sorbent (a mixture of pork and beef fat, etc.) is applied to both sides of the glass (frame) with a layer of 3-5 mm. The flowers are laid out on top of a sorbent up to 3 cm thick and left for 48-72 hours. After this period, the raw materials are removed and fresh raw materials are placed on the frames. This operation is repeated many times (up to 30 times) until the sorbents are saturated with essential oil. At the same time, the waste raw material containing a certain amount of essential oil (mainly heavy fractions) is additionally processed by extraction or steam distillation.Then the fat saturated with essential oil is removed from the glass, and from the resulting lipstick the essential oil extract(extracted) with alcohol, the alcohol extract is frozen out and the precipitated impurities (fats, etc.) are removed from it by filtration. The alcohol is distilled off under vacuum and pure essential oil is obtained.

When activated carbon is used as a sorbent, the raw material (flowers) is placed in the chamber on the nets, after which the chamber is hermetically closed and a strong current of moist air is blown through it, carrying away the vapors of the essential oil secreted by the flowers. Oil from the air is absorbed by activated carbon, best of all BAU brand (birch activated carbon), located in the adsorber, which is installed above the chamber. Activated carbon, after saturation with essential oil, is unloaded from the adsorber, subjected to elution with ethyl ether, and after distillation of the solvent, essential oil is obtained.

Method 5. Extraction with selective solvents.

Essential oils are soluble in many volatile organic solvents (hexane, petroleum ether, chloroform, diethyl ether). This property is used in cases where, on the one hand, the components of essential oils are thermolabile and are subject to destruction during steam distillation, and on the other hand, there is no need to achieve a high degree of purification (in the case of use in the perfumery or food industry). Extraction consists in the fact that the raw material in special extractors is subjected to extraction with petroleum ether or other extractant. Then the extractant is distilled off, and after removing the solvent, the resulting essential oil is a "tar" (the so-called perfume, or "odorous wax"), which contains impurities of lipophilic substances (sterols, chlorophyll, carotenoids and other fat-soluble vitamins).

Recently, the extraction of essential oils has also been carried out with liquefied gases (carbon dioxide, freon-12, etc.), but this method requires appropriate equipment that can withstand high pressure (up to 200 atm.). With the help of this method, the essential oil industry processes etc.

Sources

This method is based on evaporation and then condensation of liquid vapor, and the ability of water vapor to entrain essential oils. To obtain essential oil by this method, distillation cubes or continuously operating distillation apparatuses are used. The theoretical substantiation of the steam distillation process follows from Dalton's law of partial pressure, according to which a mixture of liquids (mutually insoluble and not chemically acting on each other) boils when the sum of their vapor pressures reaches atmospheric pressure. Steam distillation can be carried out not only at atmospheric pressure, but also under pressure with superheated steam. In this case, the ratio of water and essential oil favorably changes in favor of an increase in the distilled oil. This is explained by the fact that the decrease in the elasticity of water vapor is disproportionate to the change in the elasticity of the vapor of the essential oil. Steam distillation has the advantage over ordinary distillation in that it can be selective, since some insoluble substances are steam distilled, others are not distilled, and some of the substances are distilled so slowly that it is possible to make a clear separation between them. The disadvantage is that fresh water must be added from time to time. This is inconvenient for long periods of work.

Mechanical squeezing method

Squeezing used in cases where the raw material contains a large amount of essential oil, such as citrus fruits. A variation of the mechanical method is pressing. It is carried out on hydraulic presses.

Method of infusion or maceration.

Used in the processing of fragrant flowers. The essential oil is extracted with fat or neutral oil, heated to 60-70 ° C, the infusion of new portions of flowers on the same fat is repeated up to 10-15 times.

Extraction method.

The method is based on the use of some low-boiling organic solvent that extracts the essential oil from the raw material, such as petroleum ether, ethanol, etc. Then the solution containing the extracted oil and aromatic substances is drained from the raw material and the solvent is distilled off. The remainder is essential oil with an admixture of resins and waxes. This product is called an extract.

Anflerange.

This method is used for certain types of flowers: roses, jasmine, etc., which, after being harvested for a more or less long time, release new quantities of essential oil. It is based on the property of fatty oils and fats to absorb essential oils. In this method, the flower petals, after harvesting, are laid out on a thin layer of pork or bovine fat spread over the surface of the framed glass. The flowers are left for 24-72 hours, then replaced with a new batch of fresh flowers. When the fat is maximally saturated with essential oil, it is washed with alcohol so that fragrant products become soluble. Then the alcohol is evaporated and the finished product is obtained.

Received different ways essential oils are not exactly the collection of substances that are released by plants. This is due to the fact that under the influence of, for example, hot steam, some constituents of the volatile components may change, volatilize. In addition, the source material for obtaining essential oil can be not only freshly cut, but in some cases also dried.

Herbal essential oils industrial production are in high demand, but are often expensive. In addition, unfortunately, when buying, you may encounter a counterfeit or low-quality product. Home production can be a solution to such problems. In this case, you will receive a product of guaranteed quality and safety.

Preparing essential oils at home is a rather lengthy and sometimes laborious process, but the result is worth it.

To get high quality oil ester, you must follow certain rules for collecting plants:

You can use wild plants and plants grown in flower beds and plantations. The main thing is that they are not fertilized with chemicals.
Collect raw materials away from highways, from industrial enterprises. Pollution with industrial waste and exhaust makes any plants unsuitable for food and medicinal purposes, including for the production of essential oils.
Harvest in the morning after the dew has gone.
Choose a sunny day.
Dry harvested raw materials in a well-ventilated area. You can use a special electric dryer or even an oven at a temperature of 30-40 degrees. Keep in mind that when dried, plants can lose more than half of their original weight.

Important! In no case do not expose plants to direct sunlight - this will intensively evaporate essential substances.

Collection time

Depending on what part of the plant will be used, the collection time is determined. This is an important condition, because in different parts of the plant organism the maximum concentration useful substances determined at different times. If the timing of the collection is not observed, the resulting essential product may be less effective or even useless.

Flowers are harvested at the peak of flowering. Fully opened mature inflorescences should be chosen.
Stems and leaves are harvested before the buds appear.
If the entire aerial part of the plants is used to obtain ether, they should be collected during flowering.
Roots and rhizomes are dug up in the fall, at the end of the growing season.
Seeds and fruits are harvested after full ripening.

Important! Be sure to sort out the collected raw materials. To obtain essential oil, use only clean and undamaged plants or their fruits, without traces of disease.

How to get

Essential oils can be made at home in a variety of ways. Their choice depends on the original plant product. In addition, some methods require special equipment.

Important! Pour homemade oil into small glass containers with tight-fitting lids and store in the refrigerator. It is optimal if the glass of the container is dark.

Infusion

The method is suitable for any raw material, unless additional conditions are specified in the recipe:

Place prepared plants tightly in a glass container. Take at least 2 tbsp. l. plant mass per 200 ml capacity, but an arbitrary amount is quite acceptable.
Pour base (olive, refined sunflower or other neutral odorless oil) or 70% alcohol until the jar is full. The base must necessarily cover the plant components.
Close the jar with a lid and place in a dry cool dark place. Withstand the infusion for at least 3 days; to increase the concentration of esters in the base, the period can be 1-3 months.
Strain the alcohol tincture; Squeeze out the oil after filtering.

Important! Fill the container to the maximum so that the air layer under the lid is as small as possible.

The method is similar to the preparation of infusion:

Pack plant materials tightly into jars.
Fill with base oil.
Roll up the lids as you would for home canning.
Keep workpieces in a cool place.
Turn the jars several times a day for the first 2 weeks. Then wait for about a month.
Filter the resulting product.

Important! Do not expose jars to heat or they may explode.

Spin

The method is suitable for citrus fruits:

Fresh zest must be finely chopped and crushed with a wooden pusher until an oily liquid is released.
Further, all this mass, without removing the crust, place in a glass container; pour the base so that it completely covers the peel.
Close the jar with a lid and leave for 3 days in a cool, dry place without light.
After infusion, heat the mixture in a water bath for half an hour.
Strain through cheesecloth or a sieve, be sure to squeeze out the crusts.

Important! Citrus fruits are treated with chemicals before storage and transportation. They do not penetrate inside the fruit, but the zest can be literally saturated with them. Therefore, fruits must be washed thoroughly, you can brush or use soda. Before removing the zest, the fruits should be scalded with boiling water.

pomace

Rinse carefully selected foliage under running water. Intense washing can damage the leaves and thus promote the evaporation of esters.
Put the plants in a plastic bag for food products and beat with a kitchen hammer.
After extracting the juice, place the entire plant mass together with the juice in a glass container, pour in the base oil and shake well. Mixing will ensure maximum transfer of esters to the base.
Leave for a day in a cool dark place.
The next day, strain the liquid, squeeze out the leaves.
Repeat the entire cycle at least three times, each time using the previously obtained oil as a base.
If necessary, top up the base, not infused on the leaves, to the desired level. Each time the concentration of esters will increase.

Important! Do not heat the oil infusion unless it is specified in the recipe. Do not neglect the advice on how to mix essential oils with the base at the intermediate stage of obtaining the product. This must be done very carefully.

Distillation

The technique allows the most efficient extraction of essential substances from plants; suitable for any raw material, except for fruits and seeds. Plants can be fresh or dried. Inflorescences are best not dried.

Water-steam distillation is the most popular method of commercial production of essential oils. You can process vegetable raw materials using this method at home, but for this you will need a distiller. small units for home use They are on sale, but they are not cheap. The purchase of the device is justified if you plan to use it regularly, and your device will not pay off immediately. Homemade equipment is unreliable. Whether to do it yourself is up to you. We will not provide instructions for the manufacture of such a device.

Lay the plants in the distiller in a dense layer. Try not to break the raw material.
The water in the machine must be clean and soft. You can pour distilled water into it.
Allow to simmer for at least half an hour or, depending on the recipe, up to 6 hours.
Control the amount of water - if it boils for a long time, it will have to be added.
Filter the resulting oil through 2 layers of gauze or 1 layer of thick cotton fabric.
Drain the remaining water or reuse if the next batch of oil is made from the same plant.

Important! In this case, the essential oil, created by one's own hands, practically does not differ in saturation from the product of industrial production.

Enfleurage

The word sounds beautiful, but the process of fat extraction itself is laborious and not very aesthetic.

In perfumery production, the method is used to a limited extent, only for the most delicate flowers, such as jasmine, rose, violet, hyacinth and others. Other parts of plants are not processed in this way.

If you wish, you can try this method at home, but be patient first.

For enfleurage, you need to prepare 2 glasses, the size of which you will determine yourself. A sufficient working surface will be 30 by 30 cm in size.

Spread a thin layer of melted interior fat, pork or beef, on both glasses. The thickness of the layer depends on the size of the colors and ranges from 1 to 3 mm.
Arrange the flowers on the glass in a single layer.
Cover with a second glass and press lightly. As a result, the petals will be completely immersed in fat.
Wrap the glasses with parchment paper or cling film and seal with tape.
Put them in a cloth bag and place in a warm place for 1-3 days.
Unpack the glasses and separate them from each other.
Select the petals with tweezers.
You can remove the fat with the petals and heat in a water bath, then quickly strain. If there are a lot of petals left in the fat, the mass can be put on a sieve and heated over a saucepan. Then the fat will flow down, and the petals will remain on the grate.
Use the fat mass for the next bookmark as long as you have raw materials and patience. The more repeated cycles you carry out, the higher the concentration of esters in the resulting flower lipstick.