So many excellent essential oils, essences and extracts are readily available that you might ask why we bother with a chapter on how to extract them yourself. Two good reasons come to mind. First, water distillation of essential oils is legal everywhere, so this is a type of distillation anyone can practice, wherever they live. Second, the production of essential oils, essences and extracts is an interesting and challenging hobby in its own right.
The prohibition against distilling ethanol is a very important legal consideration in some countries, and we can't stress too highly that the ethanol extraction techniques described in other chapters may not be performed where it is illegal. Other hydrocarbon solvents may be used, such as acetone and hexane but they are toxic, and since incomplete separation of the solvent would ruin the flavor of essential oils, we prefer the simplicity of steam distillation. Indeed, water is often better than ethanol for this purpose as its boiling point is higher. Where ethanol is used in this book, it's solely for its passive solvent properties to extract or carry oils and aromatic compounds in the form of an essence, tincture or extract. These can be legally made with purchased ethanol.
What are essential oils, and where are they found? Technically, an essential oil is a water-insoluble aromatic substance that can be extracted from botanical materials with heat or solvents. In practice, the term "essential oil" is sometimes loosely applied to all flavoring or aromatic compounds, when in fact many of these compounds are not oils at all. A familiar example of a non-oil aromatic is vanilla. The vanilla bean pod is green when harvested and must be cured by fermentation and drying, which can take up to 6 months. The principal flavoring compound is vanillin, which may crystallize on the dark brown pods as they dry. Over 150 other flavored compounds are found in the pods, and they contribute to the depth, flavor and aroma of the real vanilla. Vanillin is not an oil, but a substance called a "resinoid" or "oleoresin", and is extracted from the pods together with many other compounds by soaking them in a solvent (usually ethanol) to make an essence or extract. One of the first projects we suggest you try is making your own vanilla extract. Once you've experienced the true flavor and aroma of real vanilla, you'll never want to use anything else!
There are many terms used for plant extracts, and the techniques for making them. We have assembled a list terms you are likely to encounter as you become familiar with extracts, essences and oils. Since making extracts and oils is an ancient art, often different terms are used for the same process or product.
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