Fractional crystallization

Sepulchritude Forum: The Absinthe Forum Archives Thru July 2001: Fractional crystallization
By Don_Walsh on Thursday, May 24, 2001 - 11:19 pm: Edit

And nowhere does the quote you tossed in say anything about alcohol at all. Just water.

That's where you zagged when you should have zigged.

By Don_Walsh on Thursday, May 24, 2001 - 11:17 pm: Edit

They are talking about steam distillation, distillation over boiling water. Which is notable because that is exactly how essential oils are prepared. It matters not at all whether you boil water in the pot or if you introduce steam from a generator as the results are the same.

First time I did this was in an instructional lab 30 years ago with cumin.

The usual arrangement for collecting the essential oil in question is a Clevenger trap, of which there are two varieties. One for oils lighter than water, one for oils heavier than water.

The rest of the oils are then extracted from the distillate with a solvent that does not mix with water, in a seperatory funnel. You then strip the solvent off, reunite the two samples of oil, and proceed with purification. This could be by a highly efficient vacuum fractionation such as a spinning band still, or by prep scale HPLC, depending on the required degree of seperation and purity.

By Dr_Ordinaire on Thursday, May 24, 2001 - 09:03 pm: Edit

Yep, Don, you are right. I should have said "around 400 F". I read F, typed C.

As for the other part you find objectionable, this is the information I have:

"Olea Volatilia.—VOLATILE OILS (Essential oils). Volatile oils (essential oils) are aromatic liquids of vegetable origin, practically insoluble, or but slightly soluble in water, and capable of being distilled with more or less facility in the vapors of boiling water, even though their own boiling points lie considerably higher."

By Don_Walsh on Thursday, May 24, 2001 - 01:31 am: Edit

Dr O, you are full of it.

Your boiling point for thujone is wrong by a factor of two. Thujone boils at standard atmospheric pressure at 201 C. Not 400 C.

And it is NOT TRUE that thujone "comes over lower when in an alcoholic solution".

You should stick to a subject you understand -- whatever that might be.

By Dr_Ordinaire on Wednesday, May 23, 2001 - 10:15 pm: Edit

"btw how do you achieve to leave the bitter components behind in heat distillation? Is it just pure luck that those bitter components don't evaporate before some of the good stuff? Or do you leave out some stuff at certain temperatures?"

Heiko, the essential oils of the herbs in absinthe distill at low temperature, while the other stuff (including absinthin, the bitter component of wormwood) remain behind.

One interesting fact is that thujone by itself has a Boiling Point of some 400 degree C or so, but when in an alcoholic solution, it will boil off at much lower temperatures.

Please don't tell the Thujone Talibans I said this, OK?

By Scoobydoo on Wednesday, May 23, 2001 - 07:34 pm: Edit

What exactly is the purpose of this?
Just to make a stronger drink?
What happens to the taste of the product though?

By Pantrax on Wednesday, May 23, 2001 - 04:27 pm: Edit

It may indeed not work well for making absinthe. But if I am not mistaken, the bitter components are water soluble, so at least a portion of them will be frozen in the ice, though that isn't as good as totally leaving them behind in a real distillation.

I don't know if the oils will be removed with the ice; it probably depends on whether they precipitate out at such cold temperatures. Some of them will probably be mostly removed and some hardly removed at all.

If you want to try this sort of thing at home, a good way to do it is to pour about a liter of your favorite beverage (beer, cider, etc.) into a large ziplock bag. Put in the freezer overnight. The next day, you will have a slushy combination of liquid and ice. Open the bag slightly and pour the liquid out into a glass, leaving the ice behind. If you end up with a solid block of ice instead of slush then your freezer is too cold for the alcohol level in your starting beverage. Either try something with more alcohol or set your freezer to a warmer temperature.

By Heiko on Wednesday, May 23, 2001 - 03:54 pm: Edit

Wouldn't most of the oils freeze and you'd only get almost pure alcohol?

btw how do you achieve to leave the bitter components behind in heat distillation? Is it just pure luck that those bitter components don't evaporate before some of the good stuff? Or do you leave out some stuff at certain temperatures?

But guess what I'm gonna do tomorrow - try out freeze distilling and make some beer liquor. Thanks for the inspiration, that's going to be fun ;-)

By _Blackjack on Wednesday, May 23, 2001 - 03:07 pm: Edit

I suspect this would be less than optimal for absinthe, since part of what goes on in the distillation process is the removal of some of the more bitter chemical componants of the wormwood.

By Pantrax on Wednesday, May 23, 2001 - 03:01 pm: Edit

Has anyone tried using fractional crystallization (freeze distilling) to make homemade absinthe? I've done this with apple cider to make applejack. For those unfamiliar with this process, you take something alcoholic (like beer or apple cider or wine) and put it in the freezer. The water tends to freeze into ice crystals, leaving a more alcoholic solution behind. You then simply filter out the ice and you have a more concentrated alcohol product. The finished product will not be quite the same as it would have been if you did a real distillation, but this procedure requires no special equipment.

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