Herb Oil Distillation
Answered by: Richard Alan Miller
Question from: Robert Hadad
Posted on: August 28, 1998

I am looking for some information on small scale distillation processors and technical advice on producing essential oils on a small commercial level.

Steam distillation is a very simple process. In order to best do this, it is important to understand what you are trying to do. Basically, all oils are dissolved (or go into solution) by a solvent. Most oils do not go into solution with water (or steam), but require something more serious, like hexane or benzene. Some are more simple and can be dissolved with alcohol.

Basic chemistry should be reviewed for a better understanding of these types of processes. Each herb or spice contain a complex of specific essential oils. All are important, some are more preferred than others. The best book on this subject is Gunther’s 6-volume set titled Essential Oils, now out-of-print but available through most libraries. This will list the boiling points for each oil and which one are important for recovery.

Essential oils are the simplest for extraction and can be dissolved with water. Steam makes this process much more efficient. Basically, you are taking your "mash," or herb product (which has been cut up into small pieces) and putting it into solution with water. The water is then taken to the boiling point, and the steam is then routed and collected into a cooler, where it is condensed back into water (with the essential oil).

The essential oil is dissolved by steam and is removed from the mash, or herb biomass. The remaining biomass might be resteamed for any remaining essential oil (or not), and then removed and used as compost. The essential oil is now in solution with water. If you know the specific boiling points for each of the essential oils in your crop, the water can then be further moved to make higher concentrations with your essential oil.

I have made simple steam extraction devices when I was a High School student, making a still for alcohol. Unfortunately, I left this in my locker and the device exploded. I got into trouble, of course, making alcohol in school. "The old days...."

For the farm, you can use several 55-gal drums and do some light welding with copper tubing. The copper tube will want to be made into a reflex column, where you wrap an aluminum pipe around it with cold running water. This causes the steam to cool and become a water tincture.

Tincture, by the way, is defined as a specific concentration of water (or alcohol solvent) to essential oil (or oil/fat). And that ratio of water (or alcohol) to oil is.....? For those who can not answer this is why I suggest we all need to review basic chemistry again. As this industry grows, there is now a need for more precision in the way we use terms in the herb and spice trade.

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