PLANT EXTRACTION:
the heart of Berkem’s trade
A strictly defined activity
Plant extraction is a process that aims to extract certain components present in plants. It is a solid/liquid separation operation: a solid object (the plant) is placed in contact with a fluid (the solvent). The plant components of interest are then solubilised and contained within the solvent. The solution thus obtained is the desired extract.
The solvent will eventually be eliminated to isolate the plant extract. If it is for the food industry, it is not necessary to separate it from the extract. If not, a second separation operation makes it possible to obtain a dry extract.
Nowadays, the term “extract” is frequently used incorrectly. In fact, only solid/liquid extraction is capable of producing them, but sometimes simple crushed plant powders are marketed as “extracts”.
An ancestral practice
An alliance between science and tradition
The origin of the extraction of active plant ingredients has been lost to time. It was in fact very early on that mankind discovered the benefits of plants and the first techniques for separating out what we now refer to as “extracts”.
The first extracts were essentially obtained through aqueous extraction or alcoholic fermentation, and according to procedures such as infusion, maceration, decoction and hydrodistillation. The simplicity of these procedures, as well as the tools, materials and heating methods of the time, meant that the extractor was a man of the arts rather than a scientist.
Today, this activity calls upon the use of precise automatons and adapted materials. It has benefited from advances in process engineering, phytochemistry and analytics. Moreover, new technologies to assist extraction (high-pressure, microwaves, ultrasound, etc.) are being developed.
However, the notion of expertise in plant extraction remains to this day a balanced combination of the mastery of technical parameters, and tradition.
Traditional extracts in constant evolution
Over 390,000 species of plants have been documented throughout the world to date, and botanists are still discovering around 2000 more every year. The majority of the plants used by humans are dedicated to medicine, phytotherapy in particular. A passing fad for some, medicine for others, this traditional practice is based on the use of the natural therapeutic properties of plants in treating pathologies. Although it is the oldest care technique in existence, it has been supported by various types of research (clinical and pharmacological). In particular, its success arises from a deeper understanding of plants and from a qualitative selection of varieties.
In order to respond to changing consumer demands, new and more modern medicinal formats are being introduced (gel capsules, tablets, hard capsules, etc.). Because of the advancements made in extraction methods, new medicinal properties have been discovered, and the set of active molecules in the plant are being better and better preserved.
In the spirit of modern phytotherapy, Berkem manufactures traditional plant extracts that endeavour to respect the plant as a whole. The company calls upon new technological equipment for the extraction process in order to offer quality extracts and a personalised response according to customers’ needs and expectations.
A technical process
The general process
Plant extraction is solid/liquid extraction, eventually followed by purification stages. It is thus defined as an operation of the separation of one or several constituents (solid or liquid) contained in a solid object by solubilisation in a fluid. This fluid, generally known as a solvent, may be a liquid or a gas (water vapour or supercritical fluids).
In thermodynamics, the solid object is a homogeneous mixture in equilibrium, i.e. in the absence of external disturbances it will undergo no modification. This can be compared with the treatment of heterogeneous mixtures, which can be fractionated by filtration, decantation or centrifugation, for example.
In solid/liquid extraction, this disturbance consists of an exchange of thermic and mechanical energy with the surroundings, combined with the provision of a third element, the solvent. Following this disturbance, the solid is no longer in equilibrium and the solid-solvent system will advance towards a new equilibrium through mass transfer. The whole art of extraction is a question of understanding the parameters that influence nature, and the kinetics of this mass transfer from the solid to the liquid.
General process of a solid/liquid extraction
Several separation procedures implement solid raw plant materials and lead to the production of extracts:
Graphic of the main separation processes
Atomization is a process for dehydration and drying. The liquid solution is sprayed as small droplets in a vertical enclosure, on contact with a hot air current. Water and solvent evaporate and give way to a powder, charged in molecules of interest.
Crystallization is a process of purification, allowing isolating a solution compound as solid crystals.
Precipitation is a separation technique during which a precipitate is formed (substances in solution slightly soluble in solvent). This compound constitutes then a residue which can be isolated.
Concentration is a method using separation resulting by the removal (partial or total) of the solvent. Thus, the obtained solution has a lower volume but is richer in molecules of interest.
Rectification is a fractional distillation process. Various components of the liquid solution are separated thanks to their volatility difference.
Spinning is an action of mechanical separation. The mixture is submitted to a centrifugal power, to isolate various compounds, thanks to their difference in density.
Membrane filtration consists in spreading a fluid in a physical boundary, the membrane. According to the pores diameter, the component of the fluid will be separated depending on their size.
A scalable procedure...
- Maceration: the contact stage is maintained at room temperature.
- Decoction or reflux: the contact stage is maintained at the boiling point of the solvent.
- Digestion: the contact stage is maintained at a temperature in between those of the previous two cases.
- Infusion: the boiling solvent is poured over the solid, then left to cool for a set time.
- Leaching or percolation: the solvent passes through the biomass.
No other methods are possible in the case of solid/liquid extraction. On the other hand, it is common to:
- Combine these methods with each other or with other processes such as distillation, steam distillation, rectification, etc.
- Use various solvents, either successively or in combination.
- Make use of extraction aids such as ultrafiltration, reverse osmosis, high pressure (supercritical CO2), microwaves, ultrasound, etc.
...leading to a multitude of different extracts.
A number of factors can have an impact on the quality of the plant extract, and combining them makes it possible to obtain an almost infinite number of different extracts.
The raw material is one of the most important parameters, but also the most difficult to master. In fact, even within a plant variety, there is often considerable variation in the quality depending on climatic conditions, cultivation practices, geographical origin, etc. This makes it all the more difficult to guarantee the consistent quality of the extracts.
The specificity and yield of the extractions also depend on their intrinsic parameters (quality of the solvent, choice of equipment and properties pertaining to the procedures).
Graphic of the parameters influencing extract quality
The same extraction procedure does not always lead to the same name for the extract. In fact, these names differ according to the process used and the industrial branch involved.
There are also a number of technical-commercial names on the market, which vary according to biological properties, composition, the solvents used, the botanical origin or a combination of the above.
Graphic of extract appelation and process
