When you scan the shelves at your local health food store or search the internet for tips on DIY herbal preparations you will notice that herbal extracts can be made with either alcohol or glycerin. But what’s the difference? Why would you choose one over the other? Which one is stronger? Is alcohol better than glycerin for making herbal extracts?
Actually, these are just two of several choices when it comes to extracting liquids for making herbal preparations. Known as menstrrums, these liquids can include water, alcohol, glycerin, vinegar, or even wine- and any combination thereof!
You can (and should) experiment with some of these different liquids just to get a feel for the diversity of preparations that can be made. It’s fun, it's interesting, and it's a good way to learn more about the chemistry that’s going on behind the scenes when you make herbal extracts. Alcohol and glycerin extracts, though, are by far the most commonly used. Let's investigate further!
What is glycerin, anyway? It’s a clear, thick, liquid with a sweet taste. It’s made by breaking down fat or oil (like lard or vegetable oil). It’s a byproduct of soap making, too. If you want to use glycerin, make sure it's labeled food grade.
Everyone typically thinks of glycerin as a very different substance than ethanol, and in some ways it is. You can look at it or taste it and see that for yourself. But technically, for chemistry purposes, it's an alcohol. Whoa, crazy, right? It’s also known as glycerol or glyceric alcohol. Even though it’s sweet tasting, it doesn’t contain sugar and won’t raise blood sugar levels and it’s popular for individuals who need an ethanol free alternative.
- Weaker than ethanol
- Less range as a solvent
- Less preservative power
- Tastes ok
- Weaker is ok if you are using it for children
- Doesn’t dissolve or mix with resins
- Doesn’t extract volatile oils very well
- Stable when heated
- Often used when an “alcohol free” option is needed (although teas are stronger)
- Not very good at extracting most alkaloids
Even though glycerin is a popular choice (especially when making herbal extracts for children), it leaves a bit to be desired when compared to alcohol extracts. It doesn’t pull out as many different types of constituents as alcohol (constituents are the chemical building blocks that make an herb useful). It makes a weaker preparation, and the shelf life is much shorter (usually not more than a year, if that).
The one really excellent thing about glycerin is that it’s really good at extracting tannins. This is useful if you are honing your advanced formulation skills because you can add it as part of the menstruum if you are concerned about alkaloids and tannins neutralizing one another and it acts as a buffer to keep that from happening.
So, technically, the alcohol we are talking about here is ethanol aka ethyl alcohol. That’s the drinkable kind that’s in vodka, wine, beer, etc. When you make an herbal extract you are using a combination of ethanol and water. Don’t try to make herbal extracts with rubbing alcohol (isopropyl alcohol)- rubbing alcohol is toxic. You can use isopropyl alcohol for liniments that are applied topically. Just be sure to clearly label them for external use only.
Vodka is a common extracting menstruum for herbalists to use because it’s cheap and readily available. 80 proof vodka is 40% ethanol, 100 proof is 50%. Sometimes higher proof spirits are used and diluted down to different ratios, but you need at least 20% ethanol to preserve your extract. Interesting fact: a 50/50 mixture of pure ethanol and water is known as dilute alcohol for chemistry purposes.
Here are a few bullet points for alcohol extracts:
- Good general solvent- extracts most things
- By itself is not good at extracting resins and mucilage
- Preserves preparations almost indefinitely
- Inactivates enzymes that would cause the extract to change over time
- Helps control chemical decomposition
- Mixes well with water and/or glycerin
- Not heat stable. Flammable, so store carefully.
Ethanol, by itself, is a good general solvent and extracts most things. It’s not very good at extracting minerals, gums, or mucilage (“gooey” herbs like marshmallow root or slippery elm). However, herbal extracts aren’t pure ethanol, so water takes up some of the slack and makes ethanol based extracts the winner when it comes to strength, range of constituents, and preservative prowess.
Alcohol vs Glycerin
When it comes down to it, ethanol based extracts come out the winner here. And in terms of health consequences of glycerin vs alcohol, unless you need to avoid ingesting all alcohol, period, there's not much of a case for being worried about the amount of ethanol found in an herbal extract. Ethanol is naturally found in ripe fruit, so our bodies are used to dealing with a little ethanol on a regular basis. According to The Herbal Medicine Maker’s Handbook, 20 drops of an herbal extract (60% ethanol) 3 times a day is less than 1/30th of an ounce of alcohol, so you really aren’t consuming very much at all. If you like using glycerin extracts and they work well for you, then hey- rock on. But if you are looking for higher potency and better shelf life, stick with alcohol.
Resources and Further Reading
If you are interested in learning more about the chemistry behind herbalism and the art of making herbal extracts, I highly recommend getting a few good books on the subject. My three favorites (and the ones I used to double check my info when I wrote this article) are The Herbal Medicine Maker's Handbook by James Green; A Clinical Guide to Blending Liquid Herbs by Kerry Bone; and Medical Herbalism: The Science and Practice of Herbal Medicine by David Hoffman.
All the Best,