Alcohol - part 2

Alcohol - part 2

So last week, I talked about the basic process of fermentation and how it has been/is utilized for the creation of alcoholic beverages around the world, but fermentation isn’t the end-all be-all of making alcohol. We can go one step further with distillation. Distillation is simply the process of using heat to separate components but it’s a bit more complicated than that in practice. Basically, most chemicals have very specific boiling points (the point where the liquid vaporizes) and distillation seeks to utilize the difference in boiling points of components in a mixture (like alcohol and water). So say we made our own wine (see my post on making wine if you want to try it yourself), and now you’ve got this mixture of ethanol (alcohol) and dihydrogen monoxide (water) along with a bunch of dissolved solids that give the drink distinct flavors and tasting notes. Now, we know alcohol boils 78.37 degrees Celsius and water boils at 100 degrees Celsius. So if we heat up a mixture of alcohol and water to the boiling point of ethanol, we will form a bubble (because we’re at the bubble point) and that bubble will contain more ethanol than water by concentration than the liquid it came from. Now if keep heating at that temperature until nothing else vaporizes and then we collect all of that vapor, we can cool it back down and now we have a much stronger alcoholic mixture than we started with. If you started with wine, you now have brandy. The difference now though is that we will have to use a slightly higher temperature to get a purer vapor this time.

Now what if we aren’t happy with brandy, rum, bourbon and other moderately strong drinks? What if for some reason we want our drinks to basically be jet fuel? Then we just distill it again! You may have seen bottles of vodka or other beverages that say something along the lines of “triple-distilled” or “double-distilled”. This just means they did the distillation process described above twice. Each time the temperature of distillation is just increased slightly but generally not above the temperature of the other component. So for alcohol, we don’t want to go above that 100 degrees Celsius point, in theory. We can keep distilling our drink with little stepwise increments until we get nearly 100% of one component, right? Unfortunately no. There are many mixtures out there made of two different things that can be nearly perfectly separated by distillation but water and ethanol are not one of them. Water and ethanol form what is known as an azeotrope (big word that means you can’t separate them with distillation alone). Basically water and ethanol have a very strong attraction to one another and so there is a certain point where you can no longer distill any further. For alcohol and water this is around 96.7% alcohol (200 proof, where 200 is the maximum achievable alcohol concentration by distillation). If we want to get even purer, we have to use something like a desiccant that would absorb the water or pass the mixture through a specialized filter made to only extract the water or ethanol. For most purposes, 96.7% ethanol is more than enough. You’ll generally only see 99.99% in very specialized lab situations.

Now on a side note, while it’s perfectly safe to try to make your own wine, you really should not try to do your own distillation. This is because ethanol has a tendency to break down into methanol during the heating process and methanol can easily make you go blind or kill you in very small amounts. Professional distillers harvest the beginning and end of each distillation (the heads and the tails) and dispose of them because these contain a large amount of methanol. Feel free to make your own wine and beer, but leave distillation to the professionals (and mountain men that have been doing it for a generations). So just stick to buying your own rums, vodkas, and tequilas. They’ll taste much better and you’ll be much less dead for it.