What are powdered herbs?

Powdered herbs are raw (crude or prepared) herbs that are ground or pulverized into a powder. They may be single herb products or formulas (combinations of herbs). They are not extracted or cooked.

What is an extract?

An extract is a liquid mixture obtained from adding a raw material to a solvent such as ethanol or water. In herbal extracts, the raw materials are raw (crude or prepared) herbs. It is not absolutely necessary to cook or heat the solvent to obtain the extraction, although it is common to do so. Extracts may be sold as liquid extracts (e.g. decoctions) or as tinctures (usually containing a large amount of alcohol.) They may also be sold in powder form and these are commonly called extract powders or granules. That is, powders and granules are simply dried decoctions. Some manufacturers use other solvents such as hexane, chloroform, ether, acetone, or other organic chemical solvents to extract chemical ingredients that are less soluble in water or ethanol or to improve the concentration of a specific marker chemical in order to enhance the ingredient profile of the extract. Often this is done for marketing rather than therapeutic purposes . Arguably, one can obtain more of the chemicals within a herb using organic solvents, but many of these chemicals may be undesirable.

What is the difference between extract powders and extract granules?

Of course, there are variations and proprietary technologies being employed by some manufacturers.

However, here are some general characteristics of each. Both forms come from liquid extracts that are dried to make the finished product. The most common method to make a powder is to spray dry the liquid extract. Spray drying is a method of producing a dry powder from a condensed liquid or slurry by rapidly drying with a hot gas such as nitrogen, oxygen or air. This is the preferred method of drying of many thermally-sensitive materials such as foods and pharmaceuticals. The resulting powder has a consistent particle size distribution and generally is free-flowing. A disadvantage to this method is that spray dried powders are very hygroscopic and even small amounts of exposure to water vapor (such as that normally found in air) may cause them to clump into a gummy or solid mass.

However, spray drying offers another significant advantage in that the final product can be made with little or no fillers. This means that, gram for gram, spray-dried powders will likely have a higher potency than granules. In the pharmaceutical industry, granulation refers to the process in which primary powder particles are made to adhere to a carrier to form larger, multi-particle entities called granules. Granulation is the process of collecting particles together by creating bonds between them. Bonds are formed by compression or by using a binding agent. Typical binding agents include disaccharides such as lactose or sucrose, or polysaccharides such as starch, dextrin, and cellulose.

Granulation is most commonly and extensively used for the manufacturing of tablets and capsules. Herbal extract granules undergo the same process and can be thought of as stopping the finished product before it is made into a tablet or capsule. Essentially, there is no difference in potency between extract granules and the tablets or capsules that are made from them. In fact, the main advantage to granules is that they are easier to compress into tablets.

Two types of granulation technologies are commonly employed, namely, wet granulation and dry granulation. Dry granulation uses powders and is more commonly used to make tablets from materials that may be sensitive to moisture and heat. When using a type of wet granulation called flow coating, the liquid herb extract solution is atomized and sprayed onto minute particles of a binder. The binder is either some form of starch, or a powdered form of the herb.

 What is meant when herbal extract powders/granules are called concentrates?

A concentrate is a form of substance which has had the majority of the solvent removed. Typically, this is the removal of water. Think of frozen orange juice concentrate. Usually, the concentrate is re-constituted at the time of usage by the addition of the water. Herbal extract powders/granules are Concentrates because the liquid solvent (water) has been removed. They can be re-constituted by dissolving the powder/granules in water. This is a common way that extract powders are consumed by patients, i.e. adding water to reconstitute and then drinking as a “tea”.

 Then, are extract powders/granules “concentrated”?

No. Concentration is the measure of how much of a given substance there is mixed with another substance. This can apply to any sort of chemical mixture, but most frequently the concept is limited to homogeneous solutions, where it refers to the amount of solute in the solvent. The solute in an herbal extract is the amount of dissolved solids obtained from the herbs that appear in the resulting decoction (tang, soup, or tea). The solvent is the water in which the decoction is cooked.

To measure concentration there are three methods:

1) weight/weight (gm/gm): This is common with solid mixtures, e.g. 100gm of 18K rose gold alloy would contain 25gm of copper and 75gm of gold. However, a 5% solution of salt water could be expressed as 5gm NaCl/100gm H2O.

2) weight/volume (gm/ml): This common with liquids .Using the salt water example above, its concentration could be expressed as 5gm NaCl/ 100ml H2O.

3) volume/volume (ml/ml): This is commonly used with liquids and gasses and often expressed as percent of the total volume. 100 proof Vodka is 50% alcohol and 50% water. Air is 78% nitrogen, 21% oxygen, 1% other gases

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