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Old 03-18-2012, 03:57 AM   #1
May 2011
Catonsville, MD
Posts: 50
Liked 1 Times on 1 Posts

So I bottled a five gallon batch today, after transferring to my bottling bucket, I noticed I left about 4-6 cups of beer in the fermentor. The trub had been kicked up already. No big deal, I have plenty of beer and running out is a great reason to make more. But after I got done bottling, I came back to it. It had settled again, so I had a quick thought, I will just freeze it and concentrate the alcohol in it. Just to see how that works and what results I could get. So I quickly dumped it into an container and threw it in the freezer. Then, of coarse, I forgot about it.

By the time I remembered it, it was a slushy. I threw the ice in a strainer with a bowl underneath. Broke it up with a fork and collected about a 4th of the total volume (1 cup). Now I have this mason jar full of high alcohol (theoretically) almost beer liquid, in my fridge. The remainder ice is currently melting so I can sample it.

There was a thread a bit ago where I had a convo with a guy about freeze concentration. He supposed that the remainder was just ice, while I proposed it was more like non-alcoholic beer. The ice seems to be dark, but not as dark, so maybe he is right, less the inefficiency in the freeze concentrate method, but we will see.

Now, does anyone have a deeper understanding of this process? If this tastes at all good, I might have a go at making a real beer with a super high avb (not wrapped in roadkill). Any way I can tell what my abv is without serious lab equipment? What are my sanitation concerns with freeze concentration (tonights batch wont be around in the morning, so I wasnt worried)?

Basicly just looking for other people that have tried this and there version of events and take-aways.

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Old 11-23-2012, 07:16 AM   #2
Sep 2012
Lewiston, Maine
Posts: 30


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Old 11-23-2012, 01:23 PM   #3
Aug 2010
McLean/Ogden, Virginia/Quebec
Posts: 9,661
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What happens when this is done is that if the temperature is below the freezing point of water water molecules that encounter one another tend to stick together. This is an extremely simplified model as water 'molecules' really consist of assemblages of many H2O units i.e. a water molecule is really H2nOn with n a continuously changing integer. But in any event this is, roughly speaking the way it works. The coalescing water molecules form a slush which contains no or very few alcohol molecules. If the solution is mixed the slush can't form and he freezing point of the mixture is lowered. Alcohol used to be used as antifreeze in automobile engines (though it was methanol).

As the slush does not contain alcohol the alcohol must remain behind. If the slush is removed the alcohol is concentrated. The slush will,of course, entrap some alcohol and it will entrap some of the other solutes in the beer but relatively little. Thus the remaining liquid is concentrated in both flavoring components and alcohol and this is a well known technique for strengthening cider and for making strong rich eisbeers (Kulmbacher EKU 28). As the process concentrates alcohol the TTB considers it distillation so I wouldn't advertise too far and wide that you are doing it.

A local (DC) fellow experimented with this and of course his burning question was as to how alcoholic it was. He used various techniques to calculate about 23% ABV so I invited him over to test it. We found it was actually more like 17% with the message being that calculations involving volumes/weights of ice removed etc combined with hydrometer readings don't give a terribly accurate estimate. You can read more about this at his blog:

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Old 11-26-2012, 01:54 PM   #4
Aug 2009
Posts: 976
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I did a research project for a local bar to answer the musical question “What is the freezing point of vodka?” I finally got a chemist to explain it to me.

What happens is that the alcohol/water mixture begins to freeze at some point below the normal freezing point of water, for beer lets say 30F. As it freezes, water precipitates out of solution, leaving a stronger solution. So at 30F you get a little bit of slush, at 28F a little more and so on. So the freezing point is actually on a sliding scale depending on the alcohol concentration, all the way down to the freezing point of pure alcohol at -173.2F, where the snowball would turn into a frozen block.

So you should be able to predict the alcohol based on the temperature (molal freezing point depression.) I’m probably missing something, but I wanted to point out that the freezing point is a range, not a constant.

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