B-Amazing: extracting essential oils from plants

While many of the plants growing in the Secret Garden are there for their beauty or their edible properties (and preferably both) we also discuss the use of plants and plant extracts for remedial or cosmetic purposes. Last June, we made our own rosewater; in December, we made bath salts using lemon zest.

In our last Secret Garden Club meeting, on herbs and medicinal plants, we were lucky enough to welcome Elke de Wit, creator of the B-Amazing skincare range, to talk about the nature of plant extracts and essential oils and how they are used in cosmetics and in her products.

Elke set up B-Amazing to create all-natural skincare creams based on beeswax and honey. Honey is an excellent humectant and antiseptic and beeswax locks in moisture and protects skin from damaging environmental factors. She is conscious about sourcing her ingredients from reputable suppliers who care about the high quality of their oils and she produces her aromatic creams in small batches in order to minimise the use pf preservatives. When caring for her bees she tries to handle them with care and love, trying to be as little invasive as possible. She is a supporter of the Natural Beekeeping Trust and their methods.

Scent and stress

Smell influences the central nervous system. States of mind such as anxiety, stress, or anger can cause physical change, including increased heart-rate, change in breathing patterns and muscle tone. In fact the stress and mental unrest so prevalent today can and often do lead to degenerative effects or ‘dis-ease’ in the body.

Fragrance can and does have the capacity for reversing this. Smelling something (or someone) you like precipitates pleasant thoughts. The physical reaction also causes deeper breathing and a slowing of the heart rate, similar states that are induced by meditation.

Essential oils, which carry fragrance, can have astonishing effects on a person’s well-being, whether inhaled, or applied to the skin. Recent research has established that certain essential oils can and do stimulate cellular regeneration, oils such as rose, neroli, frankincense, and myrrh, for example, making them even more desirable to the cosmetic industry.

Essential oils can also be used in food, though in MINUTE quantities: two drops to 300 or even 600ml of a pudding, ice-cream, or sauce is already sufficient to infuse a dish with taste.

Essential oils

A single essential oil is made up of hundreds of different chemical components, each one of which may possibly interact with another. There are over 300 different constituents to a rose scent, for example, some of which have not even been identified yet.

This is why it’s so difficult to replicate an essential oil synthetically. ‘Nature identical’ oils are only about 96% accurate, while the remaining 4%, the ‘trace elements’, are often what really defines a fragrance. So just as an artificial plastic rose bloom is only an approximation of the real thing, so a synthetic rose oil can’t truly replicate the real thing. Each component brings its own set of properties to the oil, so that the total result is a very complex substance.

The best way to ensure that you source a high-grade oil is to buy from a supplier with a genuine interest in the therapeutic properties of essential oils and a good reputation. NHR in Brighton is the only company B-Amazing has found where all essential oils are organic.

However, using essential oils from an organically grown plant is only part of the story. In order to extract essential oil from the plant, some form of chemical process may be necessary, or expedient.

Methods of extraction

Steam distillation

Here the plant is placed into a container, and boiling water or steam is passed through the plant matter, then forced into an outlet pipe that carries away the vapours produced. The boiling water/steam softens the tissues of the plant material so that it releases its essential oil content. These then flow through a pipe that passes through a jacket of cold water, which acts as condenser and the resulting liquid then drips into a second vessel.

Oil and water have different densities and so will separate. The oil floats on top of the water and can be skimmed off. Some essential oils (such as rose, lavender, and orange flower waters) are partially soluble in distillation water, so the water can be recovered and also used, in ironing, as a skin tonic, or as an air freshener.

When we made rose water at the Secret Garden Club, we set up a very simple homemade steam distillation kit. Extracting rose oil by distillation is also possible, although yields tend to be very low making the resulting oil highly expensive. Rose oil is particularly good for healing wounds and skin regeneration.

Jasmine oil is too delicate for the steam distillation process – the heat destroys its beautiful scent.

Solvent extraction

The plant material is placed in a container with a volatile solvent, usually a petroleum ether (benzine) or hexane, Blades fitted inside the drum ensure that the solvent can completely penetrate the plant tissue. What remains is plant waxes, essential oils, resinous matter, and chlorophyll which are dissolved out.

Hexanes are a significant constituent of gasoline. They are all colourless liquids with a gasoline-like odour, and widely used as a cheap, relatively safe, largely unreactive and easily evaporated solvent. You’ll find hexanes in screen cleaners, and the automotive industry.

However, companies are moving away from using it in the food industry to extract oil from grains or protein from soya: it’s a known carcinogen and can cause nerve system damage.

Petroleum ether (benzine) is the main ingredient of some label or sticker remover products. You’ll also find benzine in paints and varnishes.

The vessel containing the plant material and solvent is gently heated until the highly volatile solvent is vapourised off leaving

a) concrete residue if the plant material was live, such as bark, flower, leaf, herb or root

or

b) resinoid residue if it was derived from dead organic material, such as benzoin, amber, frankincense, myrrh

Frankincense and myrrh can be either steam-distilled or become a resin absolute by alcohol extraction directly from the gum resin. Benzoin is insufficiently volatile to produce an essential oil by steam distillation. If found in liquid form it’s simply a benzoin resinoid dissolved in a suitable solvent or plasticising diluent.

Resinoids are used as fixatives to prolong the effects of scent in perfumery.

The final stage of solvent extraction involves the concrete residue being subjected to pure alcohol which separates the absolute from residual wax, a process which can be repeated several times in an attempt to separate all the wax. The alcohol is then recovered and an absolute of essential oil remains. Some absolutes will still retain 2% or more ethyl alcohol even at the end of the extraction process. They should not be used for cosmetics or massage treatments.

Enfleurage

This is an ancient form of extraction. Wooden-framed glass plates were spread with fat, and freshly-picked flowers placed on top. The fat was treated with alcohol to produce an absolute. Today solvent extraction has largely replaced this process.

Expression

This is most commonly used to produce citrus oils, for example, lemon, sweet orange, bergamot, or grapefruit oils. The entire fruit is crushed or its skin subjected to abrasion by machine (in the olden days, it was done by hand). The oil, in the outer peel of the fruit, will separate from the water and pulp.

Nitrogen/carbon dioxide extraction

Oils extracted in this manner are solvent free and non-volatile matter! This is currently being experimented with but it will take time for producers of oils to switch to this method.

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