This week I continue my series on low alcohol and non alcohol brewing for home brewers. Last week in Part 1, I introduced some of the techniques used and discussed overall strategies for maintaining the proper balance in the beer. This week I’m going to dive into more detail on methods that can be practically used at home, and we’ll cover additional methods in part 3.
The Boil Off/Distillation Method
First up is probably the oldest method for making a low alcohol beer at home. In this method you brew and ferment a traditional beer, though you typically make it slightly under-strength. Then you heat the finished beer in an oven or pot at a temperature above 173 F (78 C) but less than the boiling point of water (212 F/100 C). The idea is to boil off the alcohol but leave behind the beer. In a commercial system, this is often done using a vacuum distillation system which boils off the alcohol in a vacuum. Such a system lowers the boiling point so less heating is involved.
While this is arguably the simplest method for an average homebrewer as all it requires is a large pot and reasonable temperature control, there are some significant downsides:
- The Alcohol-Beer Azeotrope – Beer and water form an azeotrope, or mixture that is hard to distill. The reason for this is that as the alcohol is boiled off, the vapor has the same proportions as the unboiled constituents (i.e. alcohol and water). The vapor pressure of the mixture makes it harder to separate, with the net effect of making the entire process take longer. Heating your beer for a long time is not good. Vacuum distillation systems used at the commercial level avoid this problem as the low pressures used mitigate the effect.
- Heating Changes The Flavor – Unfortunately heating the finished beer to near boiling temperatures for an extended period of time affects the beer in negative ways, similar to rapidly aging your beer. In fact many commercial brewers will heat their beer to simulate the effects of aging. Heating also kicks off melanoidin transformations that darken and age the beer further.
- Long Boil Times with Unpredictable Results – Because the azeotrope effect slows the entire process, the amount of time needed to achieve a target alcohol level of, for example, 0.5% is hard to accurately predict. Some homebrew sources say it could take as much as 2-5 hours to reduce the alcohol level to 5-10% of the starting level. So a 5% starting beer might take 2-3 hours of heating to achieve a 0.5% target. And you can’t really measure the final alcohol content without sending a sample to a lab as a hydrometer or refractometer won’t work here.
Low Fermentability Wort Methods
For the purpose of simplicity, I’m combining a few methods here that all have the goal of achieving a wort that has low fermentability so when we ferment our beer it ends with a low alcohol level. Typically we’re not going to achieve the 0.5% ABV threshold here, but this method may be suitable for a beer that is only 1-2% or you can combine these methods with a low alcohol yeast (covered in part 3) to achieve the 0.5% ABV threshold. For example, creating a low fermentability wort in the 1.010-1.030 range might give us a finished beer in the 0.5-2% ABV range. Also these methods are often used in combination with other methods. This includes:
- High Temperature Mash: We normally mash our grains in the 143-158 F (62-70 C) range which activates both Alpha and Beta amylase, the two main enzymes used in mashing. Beta amylase cuts short fermentable chains from starches, but is active in the lower part of that range. Alpha amylase, which is active in the higher portion of that temperature range, chops starches into chains of random lengths. As a result it tends to create longer sugar chains that are less fermentable. So if we mash at a high temperature of 162-180 F (72-80 C) we’ll create a beer with more body and relatively few fermentables.
- Cold Steeping/Quick Mash: While not technically a mash, you can “cold steep” your grains in water for anywhere from a few hours to a day. This will extract a lot of the color and flavor from the malt but leave very little in terms of fermentables. One popular variation of this then heats the grains to the high end of normal mashing temperatures rapidly for a short 10-15 minute mash and then moves directly to the boil. This develops just a small amount of fermentables needed to achieve 0.5-3% beer from a low gravity wort. The combination of the long cold steep and very short mash retains the proteins and starches for good body in the beer as well as good head retention.
With either of the above methods you can create a wort that is low in fermentability and then use either standard yeast, low alcohol yeast or an arrested fermentation (covered in part 3) to create a beer with good body.
Next week in part 3 I’m going to discuss some of the new low alcohol yeasts that make great beer but produce very little alcohol as well as arrested fermentation and other considerations for carbonating and finishing your low alcohol beer. So stay tuned for part 3!
Please subscribe for regular weekly delivery, check out the podcast, and don’t hesitate to retweet, link, like or mention any of my articles on social media.
