Thursday, 12 October 2017

THE PROCESS OF EXTRACTION



The term herbal or plant extract is used a lot in articles, books and catalogues but what is an extract? Is it the same as the original herb or plant? Or is it something different?

Extraction is like the art of making tea.

A solvent is used to extract elements or compounds from the plant or herb but which the extractor may call the drug. Each herb or plant contains lots of different chemicals such as vitamins, minerals or other components. These are called the actives i.e. the molecules that do the work for which the herb is renowned such as pain killing or reducing inflammation.

It follows then that the type of solvent determines the nature of the extract. Different chemicals in the herb or plant engage with different solvents. There are for example water soluble components, oil soluble components etc.  A variety of solvents may be used each of which has its own advantage or disadvantage and each of which is poor or better at extracting a certain component.

Some solvents have secondary effects e.g. alcohol or propylene glycol which have preservative properties.  Solvents are not necessarily interchangeable.

The solvent has a maximum carrying ability.  Once saturated the solvent cannot take up any more of the chemistry of the plant. This is the best sort of extract. Using the example of tea again you can make weak tea or strong tea so not all extracts are the same value and this is sometimes reflected in the price of a product. Weak tea goes further! Many times extracts are not added for efficacy but rather to make a product look as though it contains lots of useful items.

As noted above, an extract can be made whereby the solvent is not saturated but rather the solvent (relatively cheap) is in effect “tainted” by a plant rather than being “full” of plant.  This is a cheap way of making extracts whereby only a small or insubstantial volume of plant material is used.  Alternatively, old material is used or re-used.

These cheap extracts should not be compared with a standardised extract.  Such an extract is where a key component is certain to be present at a given level.  A common or average is found and the extract adjusted to comply.  A common means of measuring the key molecule or component present is by UV spectroscopy.

This component or tracer can be further concentrated or filtrated to a reproducible or measurable componency (also referred to as a standard extract but more correctly concentrated standard extract).  Purified extracts refer to the highest levels of certain molecules.  Perhaps other synergistic molecules are maintained to increase the activity of the plant drug.

Herbal specification data mostly mentions the quantity of plant used such as organic or other status and the dry residue as a point of reference and therefore standardisation of quality.  The quality of an extract is solely linked to its concentration or containment of active principles.  These can only be measured through proper analysis.

So not all extracts are the same in value. Seeing a herbal name on the back of a pack (the INCI list) tells you little about the real quality or value of an extract, the good, the bad and the ugly all have the same name. Price becomes some guide as does the brand name which builds trust with its promotional material. Read the core values of a brand and its claims which may even tell you the value of the extracts used.

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