Freezing point of beer

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Question:

| There is a formula based on delta(O.G.,F.G.) which can calculate | the freezing tempurature of your beer. Unfortunately I don’t have it | handy right now, but basically most beers will remain liquid down to | -3 C to -5 C. -(0.42 x Alcohol by Weight) + (0.04 x Degrees Plato of Original Wort) + 0.2 = Degrees Celcius. A 24 Plato beer (1.098) with an ABW of 8.5 would look like this: -(0.42 x 8.5) + (0.04 x 24) + 0.2 = -4.73 degrees C or 23 degrees F. There you go with the formula. -3 C is more like it with most beer. -5 C is if the beer is 10% alcohol by volume. — Judge Director of the 1st Round of The AHA Nationals – Chicago,IL 1995 Organizer – Real Ale Fest – Chicago – October 13,14 1995

Response:

Attila writes:

I have problems with keeping my bottles of lager at lagering temperature (no space inside my house). What about storing them in the garage,- this time of year the thermometer shows around 0 C. (+/- 5 C). Is there a table/formula for ABV % alcohol vs freezing point. I am sure Gravity and CO2 play some role, but that is minor. — As long as the solution is dilute (which beer is), freezing point depression (FPD) is a function of the solvent, given by the formula: FPD=Kf * m where Kf is a constant (1.86 for water in this case) and m is the molality of the solute (m=moles of solute/kg of solvent). In short, use the following formula: FPD=1.86 * 1000 * (% EtOH/46)/(1-%EtOH) where % EtOH is the percent alcohol by weight expressed in decimal (e.g. .05). Example: A typical beer has, what, 5% alcohol by weight, and the FPD equals: FPD=1.86 * 1000 * (.05/46)/(.95)= 2.13 degrees C. So the beer will freeze at -2.13 degrees. Actually, since there are more dissolved compounds than alcohol, it will freeze even colder. If the thermometer you mentioned is outside the garage, then I guarantee that the inside does not get too cold. If the thermometer is inside, then you could prevent freezing by puting the beer on the floor and covering it with a blanket or surrounding it with some mass (park your car close to it). This should keep it warm for the brief periods when the mercury falls too far below 0. Happy northern brewing. Greg Lewin Oops, sorry about the line formatting-this stuff doesn’t come frommemory, you know, and I forgot to adjust my editor.

Response:

There is a formula based on delta(O.G.,F.G.) which can calculate the freezing tempurature of your beer. Unfortunately I don’t have it handy right now, but basically most beers will remain liquid down to -3 C to -5 C. -Bob — * Robert L. Lamothe University of New Hampshire * * * * Kicking Back at the Stagger Inn. *

Response:

When I took freshman chemistry, there was a test problem: "Freddy Freshman left three bottles of beer on his window sill overnight and found in the morning that two had frozen. He analyzed them for alcohol content and found that the two that froze had alcohol content of 3.5 % by wt. and 3.8%. The one that didn’t freeze analyzed at 4.2% Compute the range of overnight low temperatures possible." By knowing the molal freezing depression (I think it is called), you could compute the answer to your question. However, it was 30 years ago that I took chemistry, so I won’t try. Jeff —

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