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| Geranium Oil Production in South Africa |
Answered by: Richard Alan Miller
Question from: Christian
Posted on: March 19, 2007
Thank you once again for your advice. I am however looking for essential oil crops. I am currently growing geranium as a crop. My area is not hot and dry. We have an annual rainfall of 1200mm. Imagine a North American climate but without the freezing winters - we do have some frost in winter and sometimes a little snow in the odd year. The problem with the geraniums is that propagation takes time -- as opposed to a crop grown from seed.
The best oils from geraniums come from a colder, more harsh environment. Propagation is best done in the winter, as outlined in my book “Getting Started.” This, along with several other good processing resources can be found at www.herbfarminfo.com.
For alternative crop selections, I would start with Gunther’s 6-volume Essential Oils (out of print but still) available at most larger libraries. This is perhaps the single best definitive study on essential oils.
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 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 contains a complex of specific essential oils. All are important, some are more preferred than others. Gunther’s 6-volume set titled Essential Oils will list the boiling point for each oil and which ones 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 re-steamed 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.
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.