Tinctures, Liquid Extracts, and Variations
February 1, 2000 3 minutes read
Tinctures, Liquid Extracts, and Variations
February 2000; Volume 2: 13
By Tieraona Low Dog, MD
Confusion exists regarding when a liquid herbal preparation should be referred to as a tincture and when it should be classified as a liquid (fluid) extract. Most liquid herbal preparations are described in terms of their herb:menstruum ratio. Menstruum is the solvent. The ratio is followed by a percentage figure that denotes the product’s alcohol content. Hence, a specification of 1:5 45% tells us that 1 kg of herb has been extracted in 5 L of a 45% alcohol solution.
A tincture is a liquid herbal preparation in which the solvent system is an alcohol/water mixture and the volume of menstruum exceeds the weight of herb extracted in it. Hence, a tincture may carry a 1:10, 1:5, 1:3, or 1:2 specification; in fact, any specification is possible provided that the number defining the solvent is greater than the number denoting the solute. A subset of tinctures within the British Pharmacopoeia and the British Pharmaceutical Codex is "tincture forte," meaning strong tincture. This is applied to tinctures of a 1:3 or 1:2 herb to menstruum ratio.
A liquid (fluid) extract is a liquid herbal preparation extracted in a water/alcohol mixture whose herb:menstruum ratio is equal to or exceeds 1:1. Beyond 3:1, herb extracts become thick and sticky because of the high solids content and thus are arbitrarily classified as soft extracts. The 1:1 ratio is the point at which a product becomes a liquid extract rather than a tincture. This definition holds true in the British Pharmacopoeia, European Pharmacopoeia, Deutches Azneibuch, Deutscher Arzneimittel-Codex, U.S. Pharmacopoeia, and all major pharmacopoeia books.
Both tinctures and liquid extracts can vary significantly in their quoted specification, so all things being equal, a 1:5 tincture is likely to be twice as strong as a 1:10 tincture, and a 1:2 tincture two-and-a-half times stronger than a 1:5. It is interesting to note that the lower the number within the ratio, the greater the difference in the amount of herb used in the extract.
The British Pharmacopoeia endorses, but does not limit to, two methods of producing a tincture—one that uses maceration and one that uses percolation.
Maceration is the addition of a known quantity and strength of solvent to a known weight of solute (the herb). The herb is cut or ground to the particle size required (typically 105 mm) and then mixed with the menstruum. The mixture sits for approximately two weeks and is then pressed, filtered, and bottled. The "spent" herb, known as the "mare," may then be used as excellent compost.
Percolation occurs by moistening coarsely ground dried herb with menstruum, packing a percolator with the moistened herb, covering the solvent, and slowly dripping the tincture. Percolations are ready within one to three days.
Both extraction techniques adequately take plant actives into solution. When producing a 1:5 tincture, the percolation method provides a total extraction of the herb. It takes 5:1 solvent to solute ratio to achieve this. Many individuals and companies make up the volume to create a genuine 1:5 extract by adding more solvent at the end, thereby negating the volume of solvent left within the percolator.
This is not general practice with macerated products. Although total extraction is not achieved, i.e., some actives are retained within the mare, the volume is then not adjusted so the overall strength should be similar. As one produces stronger and stronger tinctures, i.e., solvent to solute ratio decreases, maceration becomes the preferred method since total extraction is not achieved by percolation in this situation.
We do not advocate repercolation, which through the use of heat and vacuum destroys or alters many plant actives. The 1:5 percolation method is the most accurate. However, since what you get in a tincture depends upon what was available from the raw material, it becomes clear that stating ratios alone is not sufficient to give an accurate representation of the tincture’s true strength. A total dissolved solids figure is much more useful, as is an assay of any known specific markers.
February 2000; Volume 2: 13
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