What Is Freeze Distilling?
Freeze Distilling, or more accurately, Fractional Freezing, is the process of separating substances with different melting (boiling) points. Technically, it’s not distilling as the process of distillation involves boiling and condensation. However, Freeze Distilling is the common name when it comes to concentration of beer or other alcoholic beverages through freezing, so it will be used here.
One of the reasons Freeze Distilling works so well is that alcohol’s (Ethonol) freezing point is much lower than water; -114°C (-173°F) and 0°C (32°F) respectively. So, if you have access to a freezer, a shatter-proof container, and a bit of ingenuity, exploiting this difference is quite easy to do. Also, it’s very straight-forward to calculate the new ABV since all you need are three numbers: Starting Beer Volume, Starting ABV, and Volume Of Ice Removed (or Volume Of Beer Drained.)
Use caution, because not only does Freeze Distilling increase alcohol content, but it also magnifies the concentration of anything that’s not water in beer. Some of these may be impurities that have direct adverse effect on health, so limiting Freeze Distilling to beer and to a reasonable ABV is advised.
Methods Of Freeze Distilling
Methods can be placed into two broad categories:
- Removal of ice – Take the ice out of the container, and leave the beer. This is the most accurate for volume measurement since the volume of ice can be directly measured. However, this method can be messy and potentially lead to oxygenation of your beer.
- Draining – Remove the beer from the container, and leave the ice. This usually the easiest method, but some alcohol may be left behind. For example, wet trub or beer in a containers dead space which will not drain.
Originating in Bavaria, Eisbock is the only widely recognized beer style that uses Freeze Distilling, however any beer can go through this process. Most Bavarian commercial Eisbocks tend to be in the 9-12% ABV range. Generally, commercial beers made through Freeze Distillation have about a quarter of the volume reduced through ice removal, so consider this amount as a good starting place if you are trying this the first time.