Herbal Glycerites: What, Why, How – and a few tips.
An ATH reader asks about using magnetic stirrers, rock tumblers, and lab vibrators instead of periodic shaking to prepare herbal glycerites. Before we get to mixing, let’s back up and discuss what herbal glycerites are, why you might choose a glycerite rather than an alcohol extract, and some tips for preparing them.
Herbal glycerites are herbal extracts prepared with glycerin or a glycerin/water mixture, typically prepared in a 1:8 or 1:10 plant to solvent ratio, while herbal tinctures are extracts typically prepared in 1:3 or 1:5 plant to solvent ratio using a mixture of ethanol and water as the solvent, also called the menstruum. Glycerin is the commercial name for 95% glycerol.
Advantages of using glycerin rather than ethanol
· The final extract is alcohol free, which is an important health requirement and/or a strong preference for some people.
· Glycerin has a sweet taste, which can increase compliance, especially for children.
Disadvantages of glycerin include
· It is a weaker solvent than ethanol
· Glycerites are necessarily less concentrated than alcohol tinctures.
· It is a less effective preservative than ethanol, so extracts have a shorter shelf life
Preparing herbal glycerites
I’ll touch on some basic principle here. For detailed guidance on preparing herbal medicines, including glycerites. I highly recommend
The Herbal Medicine-Maker’s Handbook: A Home Manual By James Green
and
Making Plant Medicine by Richo Cech
Some conventional herbal wisdom
- The final percentage of glycerin in an extract should be at least 60% for it to be helf stable.
- When calculating amounts of water and glycerin proportions for your menstruum, be sure to account for the 5% water in the glycerin.
- Fresh flowers with delicate structures and aromatic constituents are well suited to extraction with glycerin. Think fresh rose petals or chamomile flowers, for example.
- If you want to use dried plant material, make sure it is very recently dried.
James Green’s favorite glycerite herbs
(You’ll find that he is more flexible about which plants and whether they’re fresh or dried)
- Burdock root & seed, fresh or dry
- Chamomile flowers, fresh or dry
- Cleavers, fresh
- Echinacea root, fresh or recently dried
- Elder flowers & berries, fresh
- Fennel seed
- Ginger root, fresh or dry
- Goldenseal root, fresh or dry; leaf dry
- Hawthorn leaf, flowers, berries
- Mugwort, dry
- Mullein flowers, fresh or dry
- Nettle herb, fresh or dry; root dry
- Oat seed, fresh; plant, dry
- Peppermint fresh or dry
- Skullcap, fresh or dry
- Eleuthero root, powdered
- Uva Ursi leaf
- Vites berries
- Valeriean root fresh or recently dried
Richo Cech’s favorite glycerite herbs
- American ginseng root, fresh
- Dandelion plant, fresh
- Echinacea root, fresh
- Elderberries, dried
- Fennel seed, green
- Mint leaf, fresh
- Mullein flowers, fresh
- Stevia leaf, fresh
- Valerian root, fresh
For the home herbalist, glycerites are typically prepared by maceration.
- Prepare your menstruum by mixing your water and glycerin, 100% glycerin is a good choice for most fresh plants
- Place your plant material in a clean jar
- Add your menstruum, making sure that the level of glycerin exceeds the level of plant material by at least ¼ inch.
- Place the jar in a dark place and shake the jar a few times a day for four to six weeks.
OK, back to mixing.
As a chemist who has worked on analyzing botanicals for many years, I have done a fair amount of method development work and mixing always shortens extraction time and improves extraction efficiency. In the lab it is never a question whether to mix, the question is which mixing technique to use.
Since glycerin is thicker and more viscous than water and alcohol, mixing could be particularly useful For medicine making in the home kitchen a magnetic stirrer would be the simplest set up, and relatively inexpensive options are available. You can learn about magnetic stirrers here. Some home medicine makers use rock tumblers to agitate the herb solvent mixture. It’s hard to say how quickly the extraction would proceed compared to traditional maceration, since there does not appear to be any data on the subject.
With that said, I personally don’t use any special equipment mixing techniques when making medicine at home. I just do it the old fashioned way and I’m always happy with the medicine.
I would like to leave you with some interesting finds from the scientific literature related glycerol as a solvent for herbal extractions.
The first study compared extracts of licorice dried root using glycerol and water, or ethanol and water. Here’s an overview of what the researchers found. (If you would like to read the article and get into the details look for the citation at the end of this post)
- 85% glycerol was optimal to extract glabridin and isoliquirtigenin
- 20-30 % glycerol gave the optimum amount of total phenolic compounds.
- The phenolic compounds were heat stable.
(Ciganović et al., 2019)
It is important to note a few things here:
- The extracts were done at a temperature of 70 °C (158°F)
- They used ultrasound assisted extraction which moves and mixes things at the molecular level, not a good option for home extraction.
- The usefulness of total phenolics measurements is debatable because the inherent variability of the methods is high, so there could be a significant uncertainty in the result.
Another study used the folk method of maceration with daily shaking for six weeks to compare ethanol/water, ethanol/glycerol/water, and glycerol/water extraction of triterpene saponins from American ginseng dried roots. Here is what they found:
- The levels of total saponins in the ethanol/water extract and ethanol/glycerol/water extract were similar.
- Saponin levels were roughly 15% lower in 65% glycerol than in 50% ethanol. That is a reasonable yield for glycerol, in my opinion.
- Individual saponins responded differently to different solvents.
- Levels of some individual saponins were similar in all extracts.
- Some saponins were found in roughly half the amount in the glycerol/water extract as in the ethanol/water extract.
- Levels of two saponins, ginsenoside f2 and XVll, were 70-85% higher in the glycerol/water extract than in the ethanol/water extract.
(Gafner et al., 2004)
I think the main takeaways from these studies are:
- Glycerin is likely a good choice in many circumstances
- It is impossible to optimize one extraction for all phytochemicals present. We (usually) make the best compromise in terms of solvent composition to the greatest variety of constituents.
Happy medicine making!
Check out my resources page for trusted sources of herbs and herbal products.
Cech, R. (2016). Making Plant Medicine. Herbal Reads LLC.
Ciganović, P., Jakimiuk, K., Tomczyk, M., & Zovko Končić, M. (2019). Glycerolic Licorice Extracts as Active Cosmeceutical Ingredients: Extraction Optimization, Chemical Characterization, and Biological Activity. Antioxidants, 8(10). https://doi.org/10.3390/antiox8100445
Gafner, S., Bergeron, C., McCollom, M. M., Cooper, L. M., McPhail, K. L., Gerwick, W. H., & Angerhofer, C. K. (2004). Evaluation of the Efficiency of Three Different Solvent Systems to Extract Triterpene Saponins from Roots of Panax quinquefolius Using High-Performance Liquid Chromatography. Journal of Agricultural and Food Chemistry, 52(6), 1546–1550. https://doi.org/10.1021/jf0307503
Green, J. (2000). The Herbal Medicine-makers’ Handbook: A Home Manual. Crossing Press.
Renata is a clinical herbalist, scientist, gardener, and woodland wanderer who helps women create profound transformation in their lives through the healing power of herbal medicine and the practice of devoted self-care. She has a BS in Chemistry from University of Maryland, a MS in Therapeutic Herbalism, and a Post Masters Certificate in Clinical Herbalism from Maryland University of Integrative Health.
Find Renata at renalynn.com and on Facebook @renatalynnclinicalherbalist.
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