Infusion methods of herbal extraction

In last week’s blog post, we discussed the evolution of herbal extraction, along with the effect of heating herbs. This week, we will be taking a look at the various methods of herbal extraction, as well as the positives and negatives of each method.

From the beginning times of herbal medicine, infusions and decoctions of medicinal plants has been the primary form of herbal extraction. It has only been during the last century or so that there has been a focus on making concentrated alcohol and/or glycerin tinctures. This may have been the influence of Western medicine that aimed to isolate active constituents of plant material, leaving the inert constituents.

However, natural healing teaches that these inert constituents (which herbal infusions and decoctions extract alongside the active components) are also important. These are passive components which can help the body to digest, assimilate, eliminate, repair, tone and maintain health. Many also act as prebiotics and probiotics to aid in gut health. This, in turn, helps the body to better absorb and assimilate the active components of the herb. Good gut health translates to a stronger immune system.

The term infusion comes from the Latin infundere, which means to pour in. An infusion is a liquid preparation made by treating fresh or dried herbs with hot or cold water to extract medicinal or nutritional properties. Aside from water, other liquids including vinegar, glycerin, wine or ethanol alcohol can be used.

There are three kinds of herbal infusions: maceration, digestion and percolation.

Maceration (also known as cold press extraction):

This is our first choice for herbal extractions. As part of this process, either fresh or dried herbs are mixed with water and a solvent (usually alcohol, but in some cases, vinegar or vegetable glycerine can be used) and left to soak or macerate for between 2 weeks to one month. After this time, the liquid is pressed out of the herb material. After this point, it contains not just alcohol and water, but the medicinal properties of the plant/s.

By this method, the whole of the plant is extracted, as opposed to a single active ingredient. This allows all the compounds of the plant to work synergistically, as nature intended them to.

The digestion method of extraction:

With this method of extraction, a maceration is heated continually below boiling point. This process hastens the solvent powers of the liquid. It allows the extraction to be prepared faster than using merely the cold press extraction method, but care must be taken to ensure the preparation is heated gently, to prevent the destruction of the herbs’ medicinal properties.

The percolation method of extraction:

This method differs from some other extraction methods in that the herbs don’t sit in their own liquid. The herbs (normally dried and powdered) are put in a large vial with a drip valve at the bottom. A filter (usually made of paper and not dissimilar to a coffee filter) is placed on top of the herbs, and a set amount of solvent (again, usually alcohol) is poured onto the filter. Over the next 24 hours, the solvent is forced through the herbs, one drip at a time. This method works in the same way as a coffee percolator.

The advantage of this method is that, just like the cold press extraction method, the medicinal properties of the herbs are extracted in their whole form, rather than just one constituent. It also allows the herbal preparation to be available much faster than a maceration. The downside is that the solvent only has contact with the herb for a short amount of time compared to the cold press extraction method. This means that it is not as potent and concentrated as the cold press extraction method.

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