Talk:Fractional freezing

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Should this be merged with freeze distillation? They sound like basically the same thing to me. sjorford →•← 14:27, 24 Jun 2005 (UTC)

Yes - and 'distillation' is a misnomer here - it's not distillation.87.102.9.154 18:20, 21 February 2007 (UTC)[reply]

In the food industry (frozen juice manufacture) it is often called "freeze concentration". 128.253.239.191 (talk) 23:50, 5 November 2008 (UTC)[reply]

I have often seen freezing points quoted for mixtures of water and alcohol. How does this fit with the gradual freezing described here? —Preceding unsigned comment added by 88.96.79.118 (talk) 22:10, 17 April 2008 (UTC)[reply]

I propose we remove the part in Fractional_freezing#Alcoholic_beverages which states ",as it can concentrate poisonous compounds, for example fusel alcohols, ...". We don't even know whether fusel alcohols are harmful (just follow the link). Without a citation, the whole "poisonous" thing is a pure conjecture, and I don't think it should be perpetuated here. 24.239.191.27 (talk) 18:59, 1 July 2012 (UTC)[reply]

Do you want to start with Methanol?

https://en.wikipedia.org/wiki/Methanol#Toxicity Kortoso (talk) 22:51, 7 October 2013 (UTC)[reply]

And yet, methanol metabolizes much more slowly in the presence of ethanol, which is also concentrated (and in much higher quantities) in fractional freezing.
https://en.wikipedia.org/wiki/Ethanol#Treatment_for_poisoning_by_other_alcohols
We certainly don't have a clear citation that fractional freezing makes the methanol content of the product any more dangerous than the methanol concentration of traditional homebrew (or even simple orange juice--which has a high methanol content). We don't even have a citation about how much methanol is typically found in a traditional commercial alcohol or homebrew to compare whether or not a concentration of that amount would be dangerous.
The following sites all imply that in both commercial and homebrewed alcohol, the amount of methanol produced is on the order of a few parts per million, meaning one would have to drink tens of litres (a few gallons) of freeze concentrated alcohol in order to reach a dangerous level of methanol toxicity. You'd die from alochol/ethanol poisoning long before the methanol got you.
http://homedistiller.org/intro/methanol/methanol
http://abcnews.go.com/blogs/health/2013/03/14/can-homemade-booze-kill-you/
https://en.wikipedia.org/wiki/Moonshine#Safety
Greg Mahan (talk) 17:27, 8 January 2014 (UTC)[reply]
I have some more information.
The Methanol wiki page shows a potential lethal dose at 30ml. The density of methanol is 0.7918 g/ml, making the listed potential lethal dose at 23.754g.
http://www.inchem.org/documents/ehc/ehc/ehc196.htm
Separations were carried out using a 3 m × 2 mm internal diameter glass column packed with 30% Carbowax 20 M at 150°C. A more satisfactory separation of methanol from the other congeners was achieved using a 180-cm Porapak P column. Methanol was found at levels of 6-27 mg/litre beer; 96-321 mg/litre in wines and 10-220 mg/litre in distilled spirits.
Accordingly, if a high-methanol wine (321mg) was freeze concentrated to say a 3-1 ratio , you would end up with approx 1g of methanol per liter of concentrated spirits. You'd still have to drink 20 liters of the stuff (approx 5 gallons) to start reaching the listed lethal doses of methanol. This 1g/liter is further mitigated by the high ethanol concentration in my example (approx 36-45% ethanol for a 3-1 freeze concentrated wine), which is one of the two primary antidotes to methanol poisoning.
After seeing these numbers, I concur that we should remove the line about fractional freezing concentrating fusel alcohols to dangerous levels.
Greg Mahan (talk) 15:44, 14 January 2014 (UTC)[reply]
I concur. Absent any scientific/medical studies that prove poisoning from "fractional distillation", then we'd best leave it out. The web has enough half-truths and rumors floating about. Kortoso (talk) 17:07, 14 January 2014 (UTC)[reply]

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#Freeze distillation, duplicate text?[edit]

I noticed that http://wiki.homedistiller.org/Freeze_distillation and the Fractional freezing#Freeze distillation subsection are in many respects verbatim duplicates. --Kevjonesin (talk) 22:56, 25 January 2014 (UTC)[reply]

#Freeze distillation[edit]

The statement: "The first material to freeze is not the water, but a dilute solution of alcohol in water." seems incorrect.

We know that pure water begins to freeze at 0° C., while ethanol begins freezing at -114° C.

See:
https://en.wikipedia.org/wiki/Water
https://en.wikipedia.org/wiki/Ethanol

Allowing for some variance due to included organic compounds in a water/ethanol solution, the water in an alcoholic beverage must still begin to freeze first. This would agree with the first statement in this section which states: "Freeze distillation is ... a process of enriching a solution by partially freezing it and removing frozen material that is poorer in the dissolved material than is the liquid portion left behind."

Hence, it must be that the "first" material to freeze is, in fact, the water.

Most technical literature refers to the melting point of a substance, as do the Wikipedia pages above. Implicitly, a substance - e.g. water - is considered to be already frozen and as transitioning to a liquid state by increasing its temperature. In contrast, we typically think of the freezing point as being attained by decreasing the temperature of a liquid substance. Obviously the melting/freezing point is the same (or nearly so) in either case. However, the order in which the ethanol versus water components respectively attain the critical temperature is reversed, depending upon the temperature from which each is being approached. That is, "first" versus "last" is simply a matter of lowering the temperature to the freezing point, versus raising it to the identical melting point.

In the present case, the (liquid) water component is indeed the first to freeze, as depicted in the external page: "Freeze Distillation of Vinegar" (http://www.alchemywebsite.com/distillation_of_vinegar.html). — Preceding unsigned comment added by 70.197.13.11 (talk) 23:33, 1 May 2016 (UTC) Yes, you are right. Whoever wrote the article has probably been confused by reading about other, more complicated phase diagrams. With ethanol/water mixtures, once they are frozen solid there are two and only two types of crystals present - pure water and pure alcohol. The mixture which freezes at the lowest temperature has about 94% alcohol - cooling that results in an intimate mixture of water and alcohol crystals, not a mixed crystal! Bethyoung1729 (talk) 11:04, 27 May 2020 (UTC)[reply]

History[edit]

The article needs a section on how this has been used in the past. I recall reading that the Romans used it to make stronger wine, for example. Dismalscholar (talk) 19:08, 9 April 2017 (UTC)[reply]