how to extract essential oils - esveal Production and sale

METHODS OF EXTRACTION OF ESSENTIAL OILS

The information provided on this site is for informational purposes only and is not intended as a substitute for the advice of a physician or other health care professional, or any information contained on any product label or packaging. The information on this site should not be used for the diagnosis or treatment of any health problem or to prescribe medicines or other treatments.

The following is part of the partial transcription of some practical operational meetings to explain the distillation of essential oils in the amateur sector and the possibility for everyone to produce an excellent essential oil themselves using the "steam current" extraction technique

The Essential Oils, oily, volatile, odorous products are extracted from plants by various methods (e.g. by engraving the plant or by separation with the help of heat) from which you choose according to the characteristics of the type of plant, the tissue that contains them, the nature and physical properties of the Essential Oil that you want to extract.
Once extracted, the Essential Oils undergo a Purification phase (also called rectification).

Extraction of Essential Oils for Squeezing

This method is chosen when the Essential Oils, as in the fruits of the Rutaceae (Orange, Lemon, Bergamot, Mandarin, etc.), are found in the otricoles of the epicarp of the fruit. Cold pressing is convenient. The squeezing can be: manual (sfumatura) on a sponge, which, from time to time, is squeezed in a collecting container, or mechanical with a suitable sfumatrice machine. With this extraction method the Essential Oils and the pulp juice are obtained at the same time..

Essential Oil Extraction for Enfleurage

The Enfleurage method (Flowering) is chosen to extract Essential Oils from parts of very delicate plant species (whole flowers or petals) that would not withstand collection, transport and excessive handling or even when the Essential Oils are present in such low quantities that separation by distillation is not possible; they would be dispersed in the water. It is also used for those flowers that, prolonging their life, give more Essence than the one (extractable by distillation) present at the time of harvesting, such as Tuberose. Enfleurage is very expensive because of the labour required. It consists in placing the flowers, immediately after the harvest, on a layer of a suitable mixture of purified animal fats (typically pig and ox or bull). The flowers are replaced every two or three days and, after about thirty replacements, the fat is saturated with essence (pommade). The fat must be extracted with absolute alcohol or other solvent which will then be evaporated under vacuum. The "pommade N° 30" means that it has been obtained by replacing the flowers on the fat 30 times. 30 is the so-called "flower value". A variant of this extraction system is the "Maceration or Hot Absorption" which consists in mixing the flowers with an amalgam of animal or vegetable fats, made liquid in a bain-marie at 50-70°C. The amalgam thus composed every twenty-four hours is squeezed and the flowers are replaced with others just picked. In this case too, the fat is saturated with essence (Pommade) and must be extracted as described above. The flowers can be immersed in the fat and closed in linen bags. This procedure cannot be carried out with flowers that contain thermolabile active ingredients and suffer a certain loss of essential oils due to their evaporation.

Extraction of essential oils with volatile organic solvents

This method is used for plants with a delicate scent that is not very rich in Essential Oils, which are easily altered by the temperature increase in the distillation process (e.g. Jasmine). Special equipment is used in which the vegetable is placed, which is passed through by a suitable solvent. The solvent must not react with the Essential Oils, be low boiling, immiscible with water, have low toxicity, no or not bad smell and be as cheap as possible. Once the extraction is finished, the solvent is removed, which, being low boiling (volatile), can be removed under vacuum and with moderate heating. In this way will remain the "concrete", not crystalline solid mass. From it the wax is eliminated, by extraction with ethanol and cooling down to -20 °C, to make it precipitate and to be able to eliminate it by filtration or centrifugation. Finally, the alcohol is eliminated through distillation at reduced pressure, thus obtaining the absolute.

Extraction of Essential Oils for Distillation

This is the most widely used technique for the extraction of Essential Oils at all levels. Considered as the most natural is also called Steam Current Extraction. It is the most used at all levels: hobbyist, small laboratory, big industry. We will describe it in detail because it is the most used for most of the plants from which the Essential Oil is extracted. This method exploits some of the physical properties of the Essential Oils previously reported. More precisely those concerning: volatility, solubility in water and density. Distillation is, in fact, a procedure through which the Essential Oils are separated from the tissues of the plant that contains them, through their "transport" by water vapour. A physical property of Essential Oils is volatility, i.e. the ability to be easily dragged (vaporized) by water vapor, despite their high boiling point. Once vaporized, Essential Oils are easily dragged by the flow of water vapor.
The vegetable, appropriately prepared, is placed in a "distillation chamber", into which water vapour is then introduced. This drags the Essential Oils with it, forming a mixture of Essential Oil + Water vapour which, passing through a cooling column, condenses and quickly separates the water from the Essential Oil. This separation occurs because water and Essential Oils are immiscible from each other and are also of different densities. They are separated by simple decantation. This type of extraction is the most widely used method to extract Essential Oils as it offers a number of advantages:
A ) The boiling temperature of the vapour/essential oil mixture is close to 100 °C, still far from the boiling temperature of the essential oils. It does not increase for the entire duration of processing and this avoids the risk of deterioration of the Essential Oils and ensures a good volatility of the same.
B) The water vapor swells the plant tissues, dilates the pores, breaks the essential cells, facilitating the release of essential oils.
C) The Essential Oil obtained in this way is easily separated from the condensed water by decantation thanks to the fact that the two compounds are immiscible and of different density.
D) There is a minimal loss of Essential Oil due to its very low solubility in water. This loss can be further reduced by using the aromatic water, which has just separated from the Essential Oils, to regenerate steam.
E) The process has a very low cost (drinking water from the tap is used) and does not create particular problems for safety at work..
F) The water vapour flow does not contain oxygen, so the Essential Oils are not subject to oxidation. The only disadvantage is the risk of thermal degradation and hydrolytic processes.

Distillation can be carried out with three different techniques: direct distillation or direct fire distillation, steam current distillation, reduced pressure distillation.

Direct distillation or direct fire

The boiler of the distiller has a perforated dividing septum (Grid) with adjustable height that divides the boiler into two parts: in the low one (about 20-30% of the volume) water is put; in the high one (70- 80% of the volume) the vegetable to be distilled is put. In reality, much depends on the type of vegetable to be distilled. This type of distiller can create problems if it remains with little water in the boiler: problems such as the formation of substances with an unpleasant odour, which make the organoleptic characteristics of the essence and/or distilled water lose. The use of a poorly controlled flame heating system can also create problems. The risk is also to heat the boiler walls that are in direct contact with the plant..

Steam distillation in current with separate boiler

This is a method that exploits the physical properties of Essences, in particular their volatility. It consists in separating the Essential Oil from the original plant using a jet of water vapour, which invests the plant tissues and "carries" the Essence with it. The process produces two final products: Distillate and Aromatic Water. The latter derives from the condensation of the same steam and is reused to generate new steam or can be collected and put on the market (Aromatic Water). Since there is a separation between the boiler, where the water vapour is produced, and the distillation chamber, where the plant is placed and where the vapours pass and vaporize the Essential Oils, the risks described above in direct distillation and in particular the burns of the plant are avoided..

Low Pressure Distillation

In this case a vacuum pump is applied to the distiller. This removes air from inside the distiller, creating a vacuum. In this way the boiling temperature of the water is lowered. The vacuum more or less pushed, gives a series of advantages that tend to safeguard those Essential Oils that are particularly unstable when subjected to high temperature, namely:
A) - Chemical reactions (hydrolysis) and thermal degradation, which would be favoured by high temperatures, are at least attenuated if not completely eliminated;
B) – Oxidation and resinification of Essential Oils are avoided thanks to the absence of air or oxygen;
C) – Highly boiling substances are distilled which, under pressure, would distill at high temperatures with consequent degradation of the other components;
D) - Fuel economy.

STEAM DISTILLATION APPARATUS

The distilling apparatus can be of different shape and size depending on the distillation requirements and the quantity of plant to be distilled. So you can go from demonstration distillers, where you distill a few hundred grams of vegetable, to distillers of enormous size (even 50,000 liters) in which you insert huge masses of vegetable that are loaded and unloaded through a hoist or pulley unless you directly connect the distiller to the loads coming from the field.
The construction material. during operation, must withstand sometimes considerable increases in temperature and pressure and is different depending on the size of the distillation unit. For small size distillers glass is used, as it is subject to easy breakage, and copper because it is an excellent (10 times more than steel) thermal conductor and easy to shape. Copper, however, is unstable and, during dwell periods, forms oxides which are then released during subsequent processing. It is also more prone to dents and fractures. For large distillers stainless steel is used to avoid possible breakages and also because it is "eternal", easy to clean, does not oxidize during periods of non-use and never releases substances. Other materials that oxidize easily are not recommended because the oxides are then released in the water and alter the organoleptic properties of the distillate.

Whatever its size, shape and the material used for the construction you can, however and always, recognize three main parts:
1) Boiler,
2) Distillation chamber,
3) Capacitor.

Boiler or heat generator

It is generally a cylindrical container with corners, those formed by the meeting between the bottom and walls, ovalized (to allow easy cleaning) in which water is placed. It must be able to withstand the increase in temperature and a slight increase in pressure, because it will be heated until the water boils and generates steam. Its size, generally twice the height of the diameter of the base, must be appropriate and it is convenient to have a side opening to add water if its level decreases in the continuation of distillation. In order to limit the loss of essential oil due to their solubility, "continuous distillation" devices are used, i.e. equipped with devices that allow, automatically, the return to the boiler of the water that separates from the essential oils.
Boiler heating can be done in several ways:

1) con vapore
2) directly on a flame (wood, gas, etc.)
3) electrically
4) bain-marie, etc.
As an energy source, gas or electricity is preferred in order to be able to precisely regulate the heating and the correct steam release. The water vapour that arises in the boiler is conveyed into the distillation chamber.

La camera di distillazione

E' un contenitore cilindrico in cui è collocato il vegetale da distillare con un’apertura, nella parte bassa, per l'ingresso dei vapori. Lasciando un po' di spazio per consentire al vapore di spargersi per tutta la dimensione della superficie di base della camera, al di sopra di tale apertura si trova una retina, o un disco metallico bucherellato, che sorregge il vegetale consentendo il passaggio dei vapori che giungono dal basso. Al di sopra del vegetale una griglia, o un setto bucherellato, ne blocca l'eventuale innalzamento durante la distillazione. L’innalzamento del vegetale porterebbe all'ostruzione dell'elmo e del foro di uscita dei vapori impedendone il funzionamento e, con l'aumento della pressione interna, sottoporrebbe a rischio di scoppio lo stesso apparecchio (soprattutto per gli apparecchi di grandi dimensioni). La camera di distillazione è chiusa nella sua parte alta con un tappo (elmo) dotato di foro per l'uscita dei vapori. In questa posizione è utile un termometro, per controllare l'andamento della distillazione. La camera di distillazione è eventualmente dotata di un manometro per controllare la pressione alla quale si sta lavorando, ed anche di una valvola che si apre automaticamente all’eventuale superamento dei valori ritenuti anomali e pericolosi, evitando così incidenti. Nella distillazione, l'aumento di temperatura determina anche l’aumento della pressione interna e viceversa. Per un aumento di una atmosfera si ha il conseguente aumento di temperatura di circa 10 °C.
Dal foro di uscita dei vapori parte poi un tubo collettore che, con due curve a 90° circa, si allontana dalla camera di distillazione e si dirige verso il basso, dove si trova l'ultima parte dell'apparecchiatura: il condensatore.

Condenser or Coil Cooler

The condenser is placed laterally to the rest of the distiller, at a distance from it, and is made so that the vapours enter from above. It is made of a copper coil (the best heat conductor), or steel or glass (only for small distillers). The internal diameter, the number of coils, the distance between them and the total length will be proportional to the distiller used. The coil is wrapped by a cavity in which the cooling water flows. The external part of the cavity has two connections for the connection, with rubber tubes, of the inlet water (connection at the bottom with the tap), and outlet (connection at the top with the drain. The cooling water enters through the outlet part of the Essential Oil. This ensures optimal refrigeration and the correct condensation of all vapours. In fact, the lowest temperature is recorded in the last coils of the path, where the water vapours and the Essential Oils must be condensed. The structure of this type of chiller is important because the coil allows, in a small space, to have a large surface area in contact with the cooling, allowing the vapours to condense effectively. The condensate is then collected in a separating funnel or other similar system, placed at the point of exit of the distillate and capable of separating the Essential Oils from water.

Shop opening hours

Organic certification - Reg.(EC) 834/2007 - controlled operator no. EW87 - Control authorised by MIPAAF IT-BIO-009

METHODS OF EXTRACTION OF ESSENTIAL OILS

The following is part of the partial transcription of some practical operational meetings to explain the distillation of essential oils in the amateur sector and the possibility for everyone to produce an excellent essential oil themselves using the "steam current" extraction technique