When it comes to essential oils, it is estimated that girls (and boys with girlfriends) will not be strangers.
The refining of essential oils can be traced back to ancient Egypt. Cleopatra cleopatra used "sesame oil" skin care, once spent a huge amount of money on the "balm garden" plants to make "sesame oil", she liked to rub jasmine balm when negotiating, "sesame oil" and jasmine balm refers to essential oils.
But why do plants produce essential oils? What chemicals are contained in essential oils? How exactly are essential oils extracted from plant material?
Today I take you to explore the secrets behind the essential oils
The street is full of essential oil advertisements, what is the composition of essential oils?
Essential oil, known as essential oil in English, is a class of secondary metabolites that exist in different parts of plants such as flowers, leaves, stems, roots or fruits, and are mostly volatile aromatic oily liquids at room temperature, mainly composed of terpenes, alcohols, phenols, aldehydes, esters, ketones and other compounds. The compound components contained in each plant essential oil range from as few as a dozen to hundreds of species, and the content of each ingredient is not fixed, which will vary greatly with plant varieties, origin, habitat, growth period, etc.
Among them, the main ingredients of the most famous lavender essential oil are linalool and linaloyl acetate.
The beloved rose essential oil contains more citronellol, geraniol and so on:
Bulgaria's Kazanlăk Rose Valley, with its excellent geographical location and climatic environment, makes it an excellent source of rose essential oil.
These compounds are also important aromatic components of essential oils. The cool odor of essential oils is mostly emitted by the compounds it contains, such as dragon brain, dragon's brain acetate, and eucalyptin. If the content of camphor in essential oils is too high, it will affect the smell of essential oils and reduce the quality of essential oils. These uniquely scented and effective essential oil ingredients are combined in different proportions to form the unique and recognizable aromatic smell of each essential oil.
If you want to know exactly what chemical components are contained in an essential oil, you need to use a gas chromatography-mass spectrometry (gc-ms), using the normal alkane mixture as the standard, calculating and comparing the retention index, and you can know the structure of the compound from the database. Interestingly, although the chemical composition of various essential oils is significantly different, due to the similar synthesis path, many chemical components can be found in a variety of plant essential oils, such as the common pinene, limonene, dipteroster acetate, terpine, cypressene and so on. The reason why essential oils have the effects of sterilization and anti-inflammatory, sedative and hypnotic, and desalination of scars is also because they contain these biologically active chemical components.
Most of the compounds in essential oils are small molecular substances with molecular weights between tens and hundreds and are easily volatile. It is also for this reason that essential oils are generally stored in sealed opaque containers, and the lid should be tightened as soon as possible after each use, and the number of openings should be minimized.
In addition to being applied to daily life, essential oils have other development and utilization values. For example, some plant essential oils have the effect of killing insects and weeds, and can be developed into biopesticides. Because essential oils are natural ingredients produced by plants, they can be degraded by microorganisms in nature, avoiding the problem of chemical pesticides polluting the environment, so they are very suitable for the needs of sustainable development.
Why do plants produce essential oils? For whitening or acne removal?
So, why do plants produce essential oils? Small partners can not be sentimental, plants produce essential oils are definitely not for human use, to give us whitening acne, people are of course from their own interests.
For example, some plants such as flowers produce essential oils in order to attract insects to pollinate; and conifers produce essential oils to avoid pests and inhibit the growth of pathogenic bacteria; and some plants such as the Italian ear of the Asteraceae family, the thorn ear, etc. can produce chemical components that inhibit the growth of other plants, and they secretly release these compounds into the air and pass them to neighboring plants, so that neighbors can grow poorly, so that they can enjoy more valuable resources such as light and nutrients. This is the so-called allelopathy, which is allelopathy in English, and is one of the necessary invasion magic weapons for a variety of exotic plants. So you see, since plants can't change their position like animals, they have to rack their brains and produce secondary metabolites with various biological activities.
Refining essential oils and steaming steamed buns are surprisingly similar at this moment...
Although plants produce essential oils that are not for human service, since humans have found such a good treasure, how can they easily let it go.
Human beings have long been using plant essential oils, extraction methods include water vapor distillation, chemical solvent extraction, supercritical fluid extraction, etc., water vapor distillation method is the most common, we see in the market lavender essential oil, Roman chamomile essential oil, rose essential oil are extracted with this method.
In fact, the equipment for refining essential oils is not complicated at all, and the principle is very simple. Everyone has seen the steamed bun scene, right?
The equipment used to refine the essential oils is a large pot of steamed steamed buns equipped with a condensation system.
For small-scale refining in the lab, we put the cut plant material into a round-bottom flask, add water to the material, and then heat it with an electric heating sleeve, and keep it slightly boiling for 2-4 hours after the water boils. At this time, the volatile components in the plant material will be steamed out with the water vapor. The round bottom flask mouth is connected to the volatile oil collector and the condensing tube, and the steamed water vapor meets condensation upwards, drips in the collector and is collected.
At this time, some components are insoluble in water and the specific gravity is less than water, will float on the surface of the water, forming what we call "essential oil"; the lower layer is water with a large specific gravity, but it is not pure water, which contains a small amount of essential oil components, but also contains complex multi-plant water-soluble compounds, we call it "pure dew".
The extraction rate of essential oils is not high, generally between a few tenths of a percent and a few percent. Because microorganisms cannot grow in essential oils, their shelf life is very long, and they are said to be able to last for one hundred years. Depending on the chemical composition of the essential oil, the extracted essential oil may appear colorless, light yellow, golden, light green, sky blue, purple and black.
Yes, you read that right, there are indeed black essential oils in this world, and the essential oil of Artemisia annua in Xinjiang, which was extracted by our laboratory (The Phytochemistry Department of the Key Laboratory of Biological Resources and Biogeography of the Xinjiang Institute of Ecology and Geography of the Chinese Academy of Sciences) not long ago, is ink black and inky black, almost like black ink!
The black color is caused by the abundance of sagebrush (The English name azaulene, pronounced yu, homophonous with "healing", is also often called sky blue hydrocarbons) in the essential oil of Artemisia annua in Central Asia. ) and its derivatives. However, the plant itself does not contain catalpa and its derivatives, which are formed by the decarboxylation reaction of matricin (matricin) in the plant as a precursor during distillation.
In some plant essential oils, the content of sagebrush or its derivatives is low, at this time the essential oils show a beautiful sky blue, such as chamomile essential oil, mugwort essential oil, Xinjiang artemisia flower essential oil and so on. It is not only the face value of a variety of essential oils, but also has the functions of anti-inflammatory and mucosal repair, which can be applied to drugs, cosmetics, daily necessities and so on.
(Author Affilications:Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences)
Author: Shao Hua
Editor: Jin Wanxia
Editor-in-charge: Gu Jun
Source: Science Compound