What Alcohol Percent to Use for Extracts & Essences

What type of solvent or alcohol by volume (abv) for what extract/essence is a common question, so let me answer it as best I can. Technically, there is no one solution that works for everything, but if you want the simple answer, I'd suggest that when in doubt, go with 60% to 65% alcohol (ethanol).

The real answer is more complex and has a lot to do with the chemistry of the compounds in the essential oils and herbs/spices you are extracting. Different compounds require different alcohol percentages, and some require no alcohol at all.

For example, a higher alcohol content, say 95%, would be used for something with a lot of terpenes, like orange oil, which is 90% plus water-insoluble terpenes. These terpenes dissolve fine in alcohol. If you want a clear solution of orange oil you'll need something higher than 80% alcohol, but you might as well just use 95% at that point. This will create a clear solution with all the terpenes retained. The flavour profile is more like triple sec, as opposed to the orange soda-type flavour you get when you separate out the terpenes.

Another example where 95% abv is useful is if you want to avoid hydrolysis (breaking down of compounds by water), and a good example is the compounds in ginger. If you just mix water and ginger root to do an extract, in a few days the gingerol compound will convert to zingerone, which has a mild heat, slightly sweet gingerbread flavour and a Scoville heat rating of 30,000. If you use dried ginger powder and 95% alcohol, the gingerol will convert to shogoal, which is much spicier (120,000 Scoville) and more in line with traditional spicy ginger beer. So it depends on what you are going for. You can find more info on the Ginger Syrup video.

One more example of high abv is ester formation. Esters comprise an acid (e.g. acetic acid/vinegar) and an alcohol (ethanol). The esters form in a high alcohol concentration when the acid combines with the alcohol, which is more likely to happen when there is an excess of alcohol. Esters exist in an equilibrium, which means that if there is a lot of water, the two components will revert back to their initial state: an acid and an alcohol. This is one reason why non-alcoholic drinks lack certain qualities that alcoholic spirits have, and that's because even if you put an ester that you buy into a non-alcoholic beverage, that ester, over time, will convert to an acid and an alcohol molecule. This can really negatively impact flavour since the fruity ester flavour disappears and some higher acids (butyl, etc.) can have unpleasant, pungent aromas.

You can use lower abv, like 35%, for more water-soluble compounds like vanilla extract. Most of the compounds in vanilla beans are partially water-soluble, and there are few terpenes, so you don't need a high abv. In fact, you can make a decent extract using no alcohol at all, just use glycerin or propylene glycol instead. You can even make water extracts, but they have a short shelf life as their is nothing to preserve the liquid.

For some things, you can use 20% abv for things like the alkaloids in gentian because those compounds are water-soluble. The reason you would use 20% alcohol is because it is a good preservative. Anything below 18% abv can still be liable to ferment and some spoilage. At the 20% abv level you tend to limit those issues.

If you think about something like Absinthe, which is in the 60% to 65% abv range, the reason for that is that it keeps the terpenes in solution, creating a clear product in the bottle. Once you add water, you get the much-celebrated louching. There is a culture built around this, so it is accepted. However, for some products like soda or non-alcoholic beverages, a cloudy appearance may be unacceptable, and this is why picking the proper solvent and solvent concentration can be tricky.

There is no single option, though 65% is a good choice when in doubt.