Depending on the nature of the plant material and properties of essential oils, they are extracted in a way that allows you to get the highest yield of good quality products. carried out in the following ways:
Raw materials with a large accumulation of essential oil are obtained mechanically, located close to the outer (integumentary) tissue, accessible for cell destruction by mechanical action. This method is used mainly in the processing of the peel of citrus fruits (oranges, lemons, tangerines). To obtain essential oils from citrus peel cells, they are destroyed by pressing or crushing, piercing or rubbing. The intensity of obtaining oils depends on the degree of ripeness of the fruit: mature fruits release oil more easily. A higher yield of essential oil is obtained by distilling it with water vapor from the crushed peel of the fruit. However, with this method, associated with elevated temperature, essential oils of low quality are obtained. The preparation of essential oils using volatile and non-volatile solvents is based on their ability to dissolve in animal fats, vegetable oils and organic solvents. way maceration(extraction with non-volatile solvents) process flowers that contain essential oils in small quantities and stop their accumulation after cutting. As a solvent, a mixture of internal beef and pork fat, melted at an elevated temperature with the addition of preservative products, is used. Of vegetable fatty oils, the most valuable are olive, almond and apricot and peach kernel oils. way extraction(extraction with volatile solvents) essential oils are obtained, the raw materials of which are adversely affected by high temperature, as well as raw materials containing many non-volatile substances and resins (oak moss and rockrose). Volatile solvents for extraction are petroleum and diethyl ethers, ethyl alcohol, acetone, methylene chloride, etc. Liquefied gases (carbon dioxide, freon) can also be used for extraction.
The extraction process consists in the fact that essential oil raw materials are processed in one way or another with a solvent. The raw material in the extractor can be in a quiescent state (in this case, it is necessary to make several infusions) or in motion through a layer of solvent. Absorption of essential oil by fats or sorbents based on the ability of fats and vegetable oils, as well as other liquid and solid sorbents (activated carbon, aluminum oxide, diethyl phthalate, etc.) to adsorb natural oil vapors from the gaseous medium. This method is used only for the processing of flowers, the biological functions of which to release fragrant substances continue after their cut (jasmine, tuberose, lily of the valley, etc.). When choosing a method for obtaining an essential oil, the properties of the essential oils in it, the quantitative content, the form of their location and the nature of their distribution are taken into account. If the raw material can be processed in several ways, then the most economical and simple in terms of technical design, but providing a higher yield of good quality essential oil, is chosen. Of all the methods, the method of distillation of essential oil raw materials with steam is the most common. As a result, essential oils are obtained in an unaltered form with a good yield, since the process proceeds at a temperature below 100 °C. In addition, in this case, it is possible to additionally obtain essential oils from distillation waters. If essential oils are found in the plant in small quantities, change their properties at high temperatures or are hardly volatile, the extraction method is used. Thus, the production of essential oils is mainly carried out by such basic methods as distillation of essential oils and extraction with volatile solvents. The sorption process is generally carried out in separate steam stripping steps to capture the essential oils. Of the other methods, mechanical is used as an independent method to obtain citrus essential oil. In the production of essential oils, the following types of steam distillation are encountered:
In practice, the distillation of essential oils is carried out in two ways: hydrodistillation and steam distillation. During hydrodistillation, the source of water vapor is water poured into the apparatus along with the processed material (essential oils or essential oil raw materials). Prolonged exposure of essential oils to boiling water leads to an improvement in their quality, for example, saponification of linalyl acetate in lavender and sage essential oils. In most cases, for the distillation of essential oils, live steam is used, supplied to the apparatus from a steam generator (boiler room), this process is called steam distillation. When distilling essential oils by hydrodistillation and with the help of externally introduced hot water vapor, the distilled liquid must first be heated to a temperature close to 100 ° C (under normal distillation conditions).
Subsequently, the formed bubbles of water vapor pass through the liquid layers without condensation (with reliable thermal insulation of the outer walls of the distillation apparatus). Essential oil evaporating from its outer surface diffuses into each such bubble, and such evaporation can occur until the total vapor pressure inside the bubble becomes equal to atmospheric pressure. Rising bubbles reach the surface of the liquid, and the mixture of vapors contained in them passes into the vapor space of the distillation apparatus. In practice, water vapor bubbles pass through the essential oil layer so quickly that the complete saturation of the mixture with essential oil vapor is not achieved, so the latter remain unsaturated.
When distilling essential oils with water vapor, the composition of the distilled fractions will be different due to the difference in the partial vapor pressure of the individual components of the essential oils. First of all, components with a higher partial pressure are distilled off, and, consequently, with the lowest boiling point, and by the end of the distillation, the components with the highest partial pressure - high-boiling ones - will predominate in the distillate. The process of distillation of essential oils from plant raw materials proceeds under somewhat different conditions compared to the steam distillation of essential oils, due to the fact that the essential oil contained in the raw material is separated from the water vapor by the cell membranes in which it is enclosed. The essential oil, located in the tissues of raw materials and inaccessible to direct exposure to water vapor, must first penetrate through the cell membranes as a result of hydrodiffusion, after which it can be carried away by water vapor.
During hydrodiffusion, some of the essential oil dissolves in the water contained in the same container as the oil, penetrates through the cell membrane swollen under the influence of moisture and heat and is carried away by water vapor. The process of hydrodiffusion lasts until all the essential oil is distilled from the raw material. Hydrodiffusion can proceed only if there is water present in the raw material itself or concentrated in the process of steam exposure to cold raw material. In this regard, air-dry raw materials at the beginning of the distillation process must be treated with wet steam or pre-moistened with water.
Preliminary grinding of raw materials before steam processing releases a certain amount of essential oil contained in it, which comes into contact with water vapor and is carried away by it in a vapor state. The essential oil remaining included in the tissues of the unground part of the raw material and therefore inaccessible to direct contact with steam must first undergo a diffusion process. Extraction has a number of advantages over the steam distillation of essential oils. The extraction process takes place at lower temperatures, so the possibility of changing the chemical composition of essential oils is sharply reduced. Extraction oils have a higher yield, they almost do not contain terpene and sesquiterpene hydrocarbons undergoing chemical transformations, and therefore the introduction of extraction oils into perfumery products ensures their high storage stability.
Extraction oils are divided into extracts (concretes, resinoids) and absolute. specific called a mixture of fragrant, tannin, coloring and other substances obtained by processing essential oil raw materials by extraction with an organic solvent, followed by distillation of the solvent. Concretes from floral raw materials are semi-products and, as a rule, are not used in perfumery. Resinoids- extracts obtained by processing raw materials with hot ethyl ether, followed by its distillation. absolute oil is a part of the concrete, soluble in alcohol, and has an odor that most fully conveys the smell of the feedstock.
Due to the presence of non-volatile resinous extractive substances in absolute oils, which prevent the evaporation of highly volatile components, absolute oils have high fixing (fixing) properties. The combination of an odor that reproduces the aroma of flowers well with fixing properties makes absolute oils extremely valuable products for use in perfumery. The most important conditions for obtaining high-quality extraction oils are the freshness of the flower raw materials, the correct choice and quality of the solvent, and the observance of the optimal process regime. Preliminarily distilled petroleum ether or brand A gasoline is used as a solvent for obtaining concretes from flower raw materials. Lichens and cistus are extracted with hot ethyl alcohol.
extracts can also be isolated using liquefied gases (freon, butane, CO, etc.). They are chemically resistant, dissolve essential oils very well, without affecting their quality. Gases almost do not dissolve the substances accompanying essential oils, have no smell, evaporate at low temperatures without residue, their cost is relatively low. The extraction process with these solvents can be carried out at low temperatures, so the extracts have high perfume qualities. At present, with the help of CO, extracts of calendula, St.
Extraction from flower raw materials is usually carried out at normal temperature in order to avoid the extraction of ballast substances. Upon receipt of resinous products - resinoids - raw materials are pre-crushed and heated. Over 95% of all essential oil raw materials are processed by the method of steam distillation in devices of periodic and continuous action. The processing of raw materials consists of the processes discussed below. Raw material preparation for processing covers all types of essential oil raw materials.
So, grain raw materials must be cleaned and crushed, flower-herbaceous and root raw materials must be crushed, and rose flowers must be fermented. Stripping Essential oils are produced using steam supplied to the apparatus. The amount of steam supplied to the apparatus, i.e. the speed of the race depends on the type of essential oil raw materials and the type of apparatus. With a decrease in steam pressure, the oil content of the waste increases.
Vapor condensation and distillate cooling occurs in the refrigerator due to heat transfer to the cooling medium. The separation of the primary essential oil and distillate is carried out in special receiver-separators called florentines. The process of separation of primary oil is based on the difference in density between oil and water, on their mutual solubility. The speed and completeness of separation depend on the temperature of the medium, the design and size of the florentine. Recovery essential oil from distillation waters is necessary because the distillate leaving Florentine partially carries away the essential oil in a dissolved state and in the form of emulsions.
On average, 5-6% of essential oils are carried away with the distillate, but the distillate contains up to 95% of rose oil, and up to 50% of basil oil. For the recovery of essential oils, the method of distillation of oils with water vapor is used - cobation and sorption of essential oils with the help of sorbents (when processing roses). The quality of the secondary cobation oils can differ significantly from the quality of the main (primary), which is associated with different solubility of the components of essential oils. In many cases, they do not blend (do not mix). Bringing essential oils into a marketable condition consists in settling, dehydration, and filtration. Rectification essential oils - distillation with water vapor at atmospheric pressure - is needed to purify them from unpleasantly smelling components and coloring substances, since some of them have a pungent odor and a darker color.
Packing is carried out in accordance with current standards in glass jars with a capacity of up to 3 liters, in tinplate jars with a capacity of up to 10 liters, in cans, steel, aluminum and stainless steel barrels with a capacity of 200 liters. packaging, labeling and storage essential oils are also carried out in accordance with current standards. Essential oil production waste contain many valuable biologically active and medicinal substances, vitamins, etc. They are used to produce livestock feed (meal, silage and fodder vitamin flour), extract various substances used in cosmetics, medicine, and the production of synthetic aromatic substances. A deep study of the composition of waste, the development and implementation of methods for their production, the expansion of production of products using already mastered technologies are topical issues. essential oil industry. Solving them will make it possible to expand the range of perfumery and cosmetic products, increase the profitability of essential oil production and, in some cases, load enterprises during the off-season. In the production of absolute oils from specific flower raw materials, wax remains as a waste - a mass of dark yellow or brown color.
After separation of mechanical impurities and bleaching, rose, azalea and jasmine wax is used in the cosmetic industry for the preparation of mascara, lipstick, etc. In addition, an additional 2% of rose essential oil is released from rose wax.
Oils extracted from plants by distillation are called essential oils; obtained by cold pressing (usually from citrus fruits) - essences; by extraction method (usually from delicate flower petals of jasmine, rose, bitter orange) - absolutes.
Distillation (from lat. distillatio - "draining drops") - distillation with water or steam, followed by cooling and condensation of steam into a liquid.
This is the main and, according to experts, the only method for extracting essential oils from plants, which can be used to obtain substances that fully comply with the definition of "essential oil". This method extracts 10% of essential oils. (Substances extracted from plants by other methods are called essences or absolutes (from which the essential oil is then isolated)).
Even the ancient Egyptians obtained essential oils by distillation. For this, the necessary raw materials - grass, flower petals, roots, resin - were placed in a huge clay vessel and filled with water, and the neck of the vessel was wrapped in several layers of linen or cotton fabric. The vessel was left to "languish" under the action of direct sunlight, it naturally heated up, and the mixture began to evaporate. At the same time, the steam passed through all layers of the fabric, and the essential oil contained in it was retained in them. It only remained to squeeze this fabric from time to time.
Later, the ancient Greeks, Romans and Persians began to use the distillation method to extract essential oils from plants and resins. The Arabs highly valued essential oils and incense for their fragrance and were the first to widely use them as ... perfumes.
Currently, it is the distillation method (of course, improved) that is the main one in obtaining essential oils. To do this, some plants are processed immediately after they are harvested, fresh, others are preliminarily kept for several days, dried, others are completely dried.
The plant materials subjected to distillation - roots, leaves, fruits, flowers, twigs, shoots, coniferous legs, moss, wood, bark and resins - are immersed in water, which is then brought to a boil and evaporated (the so-called direct distillation), or placed on a grid located above boiling water so that steam passes through the raw material located on it from the bottom up (steam distillation). This method is called the hydrodiffusion method (by the way, it is considered the most modern way to obtain an extract).
Steam destroys plant cells - essence reservoirs, while the "bags", "bags" and "tubules" already known to us, filled with fragrant essence, are emptied, it is released outside, mixing with water (in the first case) or steam (in the second).
And then it’s a matter of technology, or rather, distillation. In the process of distillation, essential oil molecules move along with steam through a special outlet tube that passes through a cooling tank, condense and merge into a special container. The steam is converted into water distillate and the plant essence into essential oil. But since oils, as you know, are insoluble in water, it is distributed either on its surface (if it is lighter than water), or sinks to the bottom of the container (heavy oils include patchouli, sandalwood, and clove). It remains only to separate the essential oil from the water and carefully collect it.
But the remaining water (water distillate) is also a very valuable product: it is saturated with aromatic substances, contains a whole range of useful components, so it is used as toilet water. For example, natural lavender or rose water is just such an aqueous distillate.
Maceration or infusion is the second method of extracting essential oil from plants. It is based on the ability of essential oils to dissolve in fats and consists in infusing raw materials with fat or neutral oil. To do this, the raw material is placed in a container, poured with warm (60 -70 ° C) vegetable oil and infused. In this case, the essential oil goes into solution.
The filtration method is similar to steam distillation, but in this case, the steam through the plant material located on the grate does not pass from the bottom up, but from the top down. Steam destroys cell membranes and essential oils go into the water with it. The resulting water distillate consists of a mixture of condensed steam and essential oil. Further - according to the same scheme: the liquid is cooled, and the oil is easily separated from the water.
The filtration method extracts essential oils from hard and woody plant materials, for example, from seeds (anise, dill, fennel, etc.), crushed bark, and some types of wood. This method reduces the oil extraction time by 2-3 times, which is very important: with such a short contact of the plant with steam, a higher quality oil is obtained.
If the raw material contains a large amount of essential oil, for example, the peel of citrus fruits - lemon, bergamot, orange, grapefruit, in this case it is extracted by cold pressing or pressing (squeezing).
The solvent extraction method is the extraction of essential oils from raw materials with various substances in which they dissolve. In this case, the aromatic substances first pass into the solvent, and then are already extracted from it.
Solvents can be natural substances (animal fat - purified pork or beef or olive oil), or synthetic - acetone, ethanol, hexane, odorless benzene, liquid butane and carbon dioxide.
The extraction method was invented in the now distant 1830: then, for the first time, menthol was obtained in this way from mint oil and geraniol from citronella. It is especially good when a delicate aroma is distorted by distillation, and therefore it is used for plants with especially delicate flower petals (roses, jasmine, orange flowers), as well as some types of resins, gums, from which it is impossible to obtain essential oils by steam distillation.
The technology used to extract the essential oil using solvent fat is called enfleurage. The enfleurage process is quite laborious and expensive. It passes without heating. Glass sheets are covered with a solvent fat, and freshly cut flower petals are laid on top of it. Fat actively absorbs fragrant volatile essential oils from the petals, and when they fade, they are removed and fresh ones are added. And so several times, until the fat-solvent is maximally saturated with essential oil. The whole process can take several days (for jasmine, for example, as many as three weeks!), until the fatty base is saturated and stops absorbing the essential oil. Then such a fragrant, essential oil-saturated fat (it is called "lipstick") is collected, cleaned of parts of plants and specks, washed with alcohol to dissolve the fragrant products in it, and then this aroma alcohol is evaporated. The result is a fragrant saturated extract called "absolute". It has a viscous, semi-solid or solid consistency, a very rich aroma and pronounced medicinal properties, so it is used only in low concentrations. Pure essential oil is extracted from the absolute, having a high concentration of all components and the highest quality.
Instead of glass sheets, you can use wooden frames with gauze sheets stretched over them soaked in olive oil. Delicate flower petals are placed on them in a dense layer and changed daily until the oil is so saturated with plant essence that it can no longer absorb it. Now it remains to soak the canvas with the resulting product in the solvent, separating the absolute from it. 80% of the absolutes (particularly rose and jasmine absolutes) are extracted by the extraction method, thanks to which even the most delicate and refined aromas are preserved.
Considering the duration and high cost of enfleurage technology, at present no more than 10% of all absolutes are obtained with its help, and they are usually expensive. Therefore, the method of extraction of essential substances is more often used using a low-boiling volatile solvent - the already mentioned acetone, ethanol (natural or synthetic), hexane, odorless benzene, liquid butane or liquid carbon dioxide. To do this, special perforated metal baskets with plant materials are immersed in a container with a solvent that extracts the essential oil from it. At the same time, the extraction process is repeated several times, replacing the spent raw materials with fresh ones, until the solvent is completely saturated with essential oil. Then the solvent is distilled off, while the aromatic substances and wax remain at the bottom of the container.
A fragrant product obtained by extraction from dry plants, resins, balms, roots, seeds, moss, is called a resinoid (this is a finished product for perfumery), from flowers - concrete. Then the resinoid (concrete) is dissolved in alcohol to remove the wax, and then, after evaporating the alcohol, the final product is obtained - the same absolute.
Unfortunately, when extracting an essential oil by extraction with synthetic solvents, traces of the solvent chemical almost always remain in it. Therefore, the absolute obtained by this method is less pure than that obtained by distillation. In addition, such not quite pure absolutes can be falsified!
The use of essential oils has long gone beyond the perfume industry and gained wide popularity. Therapists in polyclinics can now easily prescribe aromatherapy treatment, and cosmetologists even consider these drugs to be indispensable in restoring beauty. Their only drawback is their high price. But this problem is easily solved by knowing how to make essential oil at home. As practice shows, in terms of quality it is not inferior to the pharmacy one, but it is several times cheaper.
Aroma oil can be extracted from almost any vegetation, whether it is a wild bush or a noble flower from a country flower bed. But before making essential oils at home from the selected plant, it should be clarified in which part of it the maximum amount of aromatic substances is concentrated. For example, in the flowers of the May lily of the valley, despite the pronounced pleasant smell, they contain only about 0.04%, and in the fruits of the clove tree - 22%.
There are several methods for making your own essential oil. These are pressing, distillation, enfleurage and infusion. The choice of method largely depends on the type of raw material.
The easiest and fastest way to get aromatic oil, which does not require any additional devices and extra costs, is spinning. But it is good only in the case of processing citrus fruits. The essence of this method is the manual squeezing of an oily liquid from the fruit peel.
But if you build such a device at home, then the production process will practically not differ from how essential oils are made in pharmaceutical factories, and at home it will be possible to obtain a very high-quality product that is in no way inferior to pharmaceutical preparations.
The beautiful word "enfleurage" refers to a complex procedure for obtaining aromatic oils by extraction with purified solid (mainly beef) fat. The bottom line is that parts of plants are laid out on a thin layer of fat, pressed with a press and left for a while. The fat absorbs the fragrance and the result is what perfumers call a flower lipstick. Further, it is dissolved with alcohol and filtered, obtaining a pure oil. This method is very expensive and laborious, so it is used only for processing very delicate and fragile flowers of plants such as rose, violet, jasmine.
For the preparation of this aromatic oil with a subtle enticing smell, strong-smelling red garden roses are taken.
For the preparation of a natural preparation called "Mint Symphony", which relieves stress and calms the nervous system, only fresh and intact peppermint leaves are used. They must be thoroughly washed, dried with a paper towel and torn into small pieces with your hands to speed up the release of juice.
The beauty of this product, in addition to its healing properties and pleasant aroma, is that orange or lemon peels are used for its preparation. Thus, you can eat the fruit, replenishing the body's vitamin supply, and use the peel with benefit. To prepare an aromatic remedy, peels from several fruits are crushed, put in a jar and poured with any refined vegetable oil that does not have its own smell. After letting the mixture brew for a week, a jar with a loosely closed lid is placed on a steam bath for 30 minutes, after which the resulting liquid is filtered, carefully squeezing it out of the peel. Once cooled, homemade essential oil is ready to use. Before using any aroma oil for medicinal or cosmetic purposes, you should consult a specialist, because each of them has a number of contraindications. For example, mint can cause miscarriage in early pregnancy, and citrus can cause allergies in children.
There are several ways to extract aromatic substances from plants, the main ones are described below. Some of them have been used since time immemorial, others are more modern and much more productive. However, strictly speaking, only those obtained by distillation or pressing can be called essential oils.
Essential oils, like wines, have good and bad years, and like any harvest, its quality reflects the characteristics of the soil. The therapeutic effect of the same oil may be weaker if it is extracted from a plant grown in poor soil. Some crops are harvested in the summer, such as lavender, while the jasmine flowers, from which the essential oil is made, are harvested at night, when their fragrance is strongest. Flower oils, such as those from jasmine or rose, require thousands of petals to make, since they contain only a small amount of oil. This is reflected in the price of such oils (they are the most expensive). Other oils, such as those based on tea tree or eucalyptus, which have both medicinal and refreshing effects, are produced in much larger quantities by evaporation from the leaves and sometimes from the stems of plants. They, in turn, are less expensive.
Essential oils are clear, colorless or colored liquids. They are distinguished from vegetable oils by the property of volatility. Their density is usually less. They are practically insoluble in water, but readily soluble in alcohol and other organic liquids, as well as in fats, waxes and other oils. These properties are used in various methods for obtaining essential oils. Some parts of the plants from which essential oils are derived, especially flowers, tend to lose quality quickly and should be used as soon as possible after harvest. Other parts, including roots and seeds, can be stored for a long time. They are transported to different parts of the world.
Each technology for the production of essential oil has secrets and features associated with the extraction of aroma from a particular plant and the purification of this aroma from hydrocarbons that have a free radical (deterpenization). Preference should be given to gentle methods, since essential oils are very "sensitive" and easily volatilize. With careless and improper handling, their quality noticeably deteriorates, therefore, careful observance of the technology is a necessary condition for obtaining essential oils.
Distillation (steam evaporation)
This is the most economical way to extract essential oils. Many historians attribute the discovery of distillation to the Persian physician and scientist Avicenna, who was mentioned in the first chapter. But there is an assumption that this process could be used in ancient Egypt. Distillation must be carried out very carefully and correctly in order to avoid loss of valuable essential oils and possible changes in their chemical composition. Some plants are distilled immediately after harvest, others after several days. And some plants are first dried, and then the essential oil is extracted from them.
Plant mass (be it roots, petals, flowers) is placed in a container, then in water and heated, bringing to a boil, or exposed to steam under pressure. High temperature and steam destroy the structure of plant cells, and the essential oil flows out of them, oil particles and steam move through the tube to another container. There, the steam cools and turns into a liquid, which is a mixture of water and particles of essential oils contained in the plant mass. Water and essential oils are separated, essential oils are lighter than water, so they float, then they are collected. This is the most accepted distillation method for extracting aromatherapy oils, and purists believe that only an oil obtained in this way can be called an essential oil.
The water passing through the distilled plant is saturated with aromatic substance and reused, it can be used as an eau de toilette, like lavender or rose.
The first distillation gives the best quality. Re-distillation of the resulting oil is called rectification. Repeated and subsequent distillations produce cheap oils unsuitable for aromatherapy.
In this production technique, the selection of the optimal steam temperature is very important, since intensive thermal treatment increases the yield of essential oil at the expense of its quality. That is why domestically produced essential oils often do not meet international standards.
Spin (pressing)
This method is used exclusively for citrus fruits: bergamot, grapefruit, lemon, real lime, tangerine, orange. Oil is secreted from small sacs located under the surface of the fruit. Initially, the oil was simply squeezed out, squeezing the fruit with your hands. The liquid was collected with a sponge and then squeezed into a glass. Indians, Chinese, Japanese do not disdain to work in such "old" ways. Why don't you squeeze the oil out of a citrus fruit right in your kitchen?
However, given the labor costs, at present, citrus essential oil is extracted using special combines. A lot of orange essential oil is produced by fruit juice factories in the USA. This is not the best oil, because fruit growing uses pesticides and chemical fertilizers, and they can spoil the oil. The best oil for aromatherapy is naturally grown fruit oil.
Unfortunately, some citrus oil factories distill the pressed peel to effectively separate the oil. Obviously, such an essential oil will be of lower quality, but it is often added to the pressed oil to increase the yield of essential oil, and hence income.
Extraction from solution
Nowadays, chemical solvents are used in industries such as ethyl alcohol, petroleum ether, hexane, etc. In this method, heated solvents take oil from plant material, then the solvent is distilled off at low temperature, leaving only an odorous substance known as " flower mass. The extraction process from the solution does not produce essential oils. The resulting extract is called "concrete"; this thick waxy mass contains about 50% essential oil. This method is used for flowers, gums, resins and absolutes (thick highly concentrated liquids) and resinoids are obtained - fragrant extracts of resins.
If dry plants were subjected to extraction - resins, balsams, roots, seeds, moss, then the fragrant product remaining at the bottom of the vacuum is called a resinoid. This is a finished product for perfumery.
If flowers were subjected to extraction - violets, tuberoses, mimosa, roses, jasmine, this product is called concrete, and it is not the final product. The concretes are treated with alcohol to remove the wax, then the alcohol is removed.
The method is used to increase the yield or to obtain oils in the case when there are no other methods. However, jasmine, unlike other flowers, is treated with hot water and steam. This method is more suitable for the production of oils for perfumery, rather than aromatherapy. The absolute (absolu), although to a small extent, always contains traces of a solvent. Therefore, when using an essential oil for aromatherapy purposes, it must be carefully analyzed to prevent the presence of substances harmful to the body.
Absolutes
To obtain an absolute from aromatic plant material (flowers, leaves, etc.), hydrocarbon solvents are used - such as gasoline or hexane. The plant material is placed in a solvent and heated slowly to extract the aromatic molecules, which go into solution. The solution is then filtered to separate the concrete. Concrete is a hard, wax-like mass. It contains approximately 50% wax and 50% volatile essential oil such as jasmine.
To isolate the absolute from the wax-like mass of concrete, the latter is mixed with pure alcohol to dissolve the molecules of the aromatic substance, and then cooled. The mixture is filtered to remove unwanted impurities and separate insoluble substances. Then, creating a vacuum, the alcohol is slowly evaporated. The result is a thick, sticky, colored liquid, which is called the absolute.
The described method is widely used for roses, jasmine, neroli. But, although to a small extent, traces of the solvent always remain. Therefore, the absolute will never have the purity that can be achieved by obtaining essential oils by distillation. Absolutes are expensive and are sometimes falsified. Purchase goods only from a reliable supplier.
Resinoids, fragrant resin extracts
The extraction of essential oils with solvents can be used for gums and resins in order to obtain fragrant extracts. At the site of damage to a tree or plant, a substance protrudes; when thickened, it becomes solid or plastic - this is the resin. For the needs of production, resin is obtained by making incisions in the bark or trunk. The exposed resin hardens in air.
Natural fragrance resin extracts are obtained using hydrocarbon solvents such as petroleum ether*, hexane or alcohol. Solvents are removed by filtration followed by distillation. If a hydrocarbon solvent is used, the result is a resinoid, a fragrant resin extract (eg, benzoic resinoid). If the solvent was alcohol, then the absolute of the aromatic resin is obtained. For example, absolutes of aromatic resins of frankincense and myrrh can be extracted from resin - raw hardened plant juice that stands out on sections. However, both can be extracted by steam distillation, resulting in an essential oil.
Essential oils and scented extracts (resinoids) may contain small amounts of the solvent used in their extraction (eg ethyl alcohol). Resinoids are often used in the perfume industry to provide longevity.
Enfleurage (extraction of aromatic substances from flowers)
This method was used in ancient Egypt more than 5000 years ago. This ancient method, which allows you to get the absolute, and invented by our non-lazy ancestors, is used less and less, due to the considerable duration and laboriousness, and hence the high cost. In our time of continuous commerce, they are mainly concerned not with quality, but with the cheapness of the cost of the product. Previously, the process was used to obtain fragrant extracts from delicate flowers, such as jasmine, that continue to be fragrant even after they have been cut. The process uses odorless purified cold fat (pork or beef), applying it to sheets of glass in large rectangular wooden frames. The flowers are laid out on a layer of fat that absorbs the essential oil. About a day later, spent flowers are replaced with new ones. The process is repeated many times until the fat has absorbed enough essential oil. Fat rich in aromatic substance is called lipstick. Lipstick is dissolved in alcohol and then processed. The alcohol evaporates and a pure absolute is obtained.
Extraction with carbon dioxide
This is a relatively new method, it has been used only since the 80s of the XX century. The cost of the product is high due to the high cost of equipment. The process was developed for the perfume industry. The oils produced in this way are expected to be of high quality, purity and natural state, just like inside a living plant. And of course, they will be free of impurities and carbon dioxide.
The price of the currently available product is too high for an aromatherapist. However, as prices fall and production increases, the resulting oils will become more affordable. The new essential oils have a different chemical composition than those already used, and therefore more research will be needed to determine their therapeutic effects.
Hydrodiffusion/percolation
Hydrodiffusion, or percolation, is the most modern way to obtain an extract. The process is faster than distillation, and the equipment used is much simpler than carbon dioxide extraction. A scattered jet of steam (spray) is passed from top to bottom through the plant material placed on the grate. Then the resulting liquid, and it consists of a mixture of condensed vapor and essential oil, is cooled. As with distillation, essential oil and water can be easily separated from each other. Although this method is promising, research is still needed to determine the place of such oils in aromatherapy.
Maceration (soaking)
The maceration method is based on the dissolution of essential oils in vegetable fatty oils. The crushed plant (chamomile, yarrow, St. John's wort, calendula, etc.) is placed in a flask with warm vegetable oil, and kept in the light for seven days (the solution is shaken periodically), the cells with the aromatic substance are destroyed and the essential oil goes into solution. It is best to use a dried plant, which has less moisture. After filtering, the oil is poured into a tightly closed glass vessel and stored in a cold, dark place, it is ready to use for massage. This is how calendula, carrot, peach oils are obtained.
Why don't you make your own oil at home? Half fill a glass jar with your chosen herbal material (such as lemon balm). Add warm vegetable oil so that the jar is full. It will be very good to add a little (about 10 percent of the vegetable oil by volume) common wheat oil to protect the entire mixture from spoilage. Close the jar with a lid and store for at least a week. Remember that the contents must be thoroughly shaken daily. Once the time has passed, filter the plant material, bottle and label.
Essential oils obtained in various ways and their volatile functions are not exactly the same set of substances that are released by plants. This is due to the fact that under the action 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.
The big advantage is that the technologies for obtaining essential oils are quite simple and there is a raw material base for industrial essential oils. Essential oils can be quite easily obtained from the waste accumulated during the harvesting of wood: spruce, pine, fir and trees of other species. And these wastes are huge. Studies of their component composition and standardization are organizationally easy to solve.
The average yield of essential oil from 100 kg of vegetable raw materials is: eucalyptus - 3 kg, lavender - 2.9 kg, sage - 1.4 - 1.7 kg, chamomile - 0.7-1 kg, etc. To obtain 1 kg of rose essential oil, it is necessary to process 1-2 tons of plant petals, and only 50 g of essential oil is obtained from 100 kg of bitter orange flowers. The cost of an essential oil depends on the yield of oil per 1 kg of an ether-bearing plant. The lower the yield, the more expensive the essential oil, although there are exceptions.
Many fragrant oils formerly derived from flowers, such as carnation, gardenia, lily, are now produced almost entirely synthetically. In the pharmaceutical industry, these chemically synthesized products are referred to as "natural copies". Natural copies are not essential oils and cannot be used in aromatherapy.
It is believed that only natural oils (unrefined, undiluted) obtained directly from the distillation apparatus and having certificates of quality and compliance with international standards (ISO) have real and full aromatherapeutic properties.
The use of essential oils is quite common and has many followers. But it should be remembered that the quality of essential oils is an extremely important condition for the effectiveness and safety of aromatherapy. Only natural essential oils, unadulterated, undiluted and free of hazardous substances, have a full range of medicinal properties and, when used correctly, do not cause allergies and do not have a toxic effect.
Literature: 1. Allison England. Aromatherapy for Mother and Child. 2. Anastasia Artyomova. "Aromas and oils healing and rejuvenating." 3. Vladislav S. Brud, Ivona Konopatskaya. "Fragrant Pharmacy. Secrets of Aromatherapy". 4. Denis Vicello Brown "Aromatherapy". 5. Lavrenova Galina. "Inhaling the marvelous aroma. Aromatherapy is a pleasant and easy way to heal." 6. Leonova N.S. "Aromatherapy for beginners". 7. Libus O.K., Ivanova E.P. "Healing Oils" 8. Tatyana Litvinova. "Aromatherapy: A professional guide to the world of scents". 9. Novoselova Tatiana. "Aromatherapy". 10. Dmitrievskaya L. "Deceiving age. Practices of rejuvenation". 11. Kedrova Maria. "Fragrances of beauty and health. Secrets of Cleopatra". 12. Nikolaevsky V.V. "Aromatherapy. Handbook". 13. Semenova Anastasia. "Oil Treatment" 14. Edited by Zakharenkov V.I. "Encyclopedia of aromas". 15. Carol McGilvery and Jimmy Reed. "Fundamentals of Aromatherapy". 16. Wolfgang Stix, Ulla Weigerstorfer. "In the Kingdom of Smells". 17. Mirgorodskaya S.A., "Aromology: Quantum Satis".
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.
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, they contain 0.02-0.10% in rose flowers, and 20-22% in clove buds, 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 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 in which the essential oil is found in the plant (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). 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 by various methods. A variety 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 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 when distilled 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 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, the low yield of oil makes it possible to obtain only aromatic water 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 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. 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. The insoluble matter is filtered off under strong cooling to separate from the waxes, and the alcoholic solution is decolorized with activated charcoal 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 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 fatty 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.
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.
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. Its good quality is that it does not contain phototoxins.
The International Organization for Standardization ISO (ISO) defines essential oils as follows:
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:
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 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.
