Producing Traditional Hot Water Powdered Extracts
When extracting plants, fungus, and other materials for medicinal use, the traditional method is called a Hot Water Extract. This process is composed of two distinct steps, and the results is a potent, full spectrum powdered extract. Two distinct steps are required to be able to capture and concentrate the many different types of compounds present in the raw materials. Some compounds will be soluble in water and other compounds will be soluble in alcohol. When a hot water process is used, both the water soluble and the alcohol soluble compounds are captured.
Before the actual extraction process begins, several important steps must be carried out. This process is the preliminary preparation:
- Bulk collection of raw materials;
- Hand sorting and selection of raw materials (for quality) and washing;
- Powdering (grinding and/or crushing) and sieving of the powder to increase the surface area for better extraction.
Once the herbs have been gathered, sorted, washed, and powdered, they are ready for the actual extraction process to begin.
Stage One: Hot Water Processing
Within chemistry, water (H₂O) is called the universal solvent because of its ability to dissolve most things—in fact, water can dissolve more substances than any other liquid (as explained by the Khan Academy). This makes water an important solvent in producing herbal extracts. Water is the primary extraction solvent used in hot water powdered extracts.
In the hot water processing step, the powdered herbs are combined with water and the two are heated to between 100° and 110° Centigrade. The exact heat and the length of time over the heat will vary depending on the herb being extracted and the final concentration (a 10:1 extract will take less time to produce than a 50:1 extraction) that is desired. This process—called stoving—may be repeated several times.
When the hot water extraction process is complete, the solution of herbs and water is vacuum pumped to produce the desired concentration. The outcome is a highly concentrated combination of extracted herbs and water, which will go onto the next step.
Stage Two: Alcohol Precipitation
Once the desired compounds are captured using hot water, it is time to precipitate that mixture of herbs and water, so as to separate what will become the powdered extract from the water. Essentially, alcohol precipitation allows the compounds that have been dissolved in water to be transferred back to the solids.
In this step, the concentration of herbs and water from step one are combined at a 1:3 ratio with alcohol (95% ethanol), so that for each part of herbs and water there are three parts alcohol.
This is solution agitated for 15 minutes and then set aside for 12 hours so that the desired compounds are able to be fully extracted into the alcohol. Once it sits for 12 hours, the liquid and the solids are separated (the water and alcohol is evaporated leaving behind their extracts). Finally, the extract is spray dried at a temperature of 70°-100° Centigrade, and the resulting powder is further crushed, stirred, and sieved.
Other Extraction Methods
Because this extraction method is called a hot water extract, but in fact uses both hot water and alcohol as an solvents, there tends to be confusion surrounding both what this process entails and how it differs from other extraction processes.
Throughout the world and throughout history, humans, have used herbs (which includes plants, fungi, and other substances) as a medicine. Within all these traditions, different extraction preparations have been used, including soups, teas, fat extracts like medicinal oils and salves, and alcohol extracts like medicinal beers, wines, and tinctures. But when referring to the modern, scientific application of using herbs as medicine and how those extracts are used, there are three main extraction methods:
- Hot water powdered extracts (discussed above);
- Ethanol/alcohol powdered extracts (learn more here);
- Liquid (tincture) extracts (learn more here).
The hot water extraction method is by and far the most widely employed extraction method in producing powdered extracts for medicinal use. What is commonly believed to involve only a single step of extraction using water, actually occurs in two steps (as shown above), one involving hot water and one involving ethanol (alcohol). This is an important extraction method, and many of the scientific studies on the uses of medicinal herbs use this process (as can be seen by searching NCBI's PubMed or Google Scholar).