If you are doing research on cold brewing beer you may be confused by some of the information you are uncovering. This is because some people consider cold brewed beer as being a beverage that is part beer and part coffee. However, others like ourselves consider cold brewing beer to be an actual brewing technique also referred to as cold fermentation which is used when brewing lagers.
Difference Between Lagers and Ales
The key to understanding cold brewing beer is first understanding the two major differences between brewing lagers versus ales. The first difference is the yeast that is used to brew them. Ales use top-fermenting yeast, which results in a quick fermentation, usually within 5 – 10 days. Whereas lagers use bottom-fermenting yeast that results in a much slower fermentation.
The other major difference when it comes to brewing these beers is the temperature they are brewed at. When brewing an ale you will strive to keep the temperature range to 60 – 78 degrees Fahrenheit, whereas a lager requires a cold fermentation range between 48 – 58 degrees Fahrenheit which is why it is called cold brewing beer.
Cold Brewing Beer Explained 
With top-fermenting yeasts, you can typically detect flavors produced by esters and phenols within the beer itself. With cold brewed beer you typically will not experience these sorts of flavors. This is because part of the process of making these beers involves a 3 – 5 week lagering stage where upon completion of the initial fermentation the beer is placed in a cold environment with temperatures hovering around 32 degrees Fahrenheit and left to age and condition.
During this cold fermentation stage, the beer undergoes a flavor-altering process that results in a crisper, smoother tasting beer. This is a result of the colder temperature causing the flavor-altering proteins and yeasts such as fruity tasting esters, acetic and lactic acids to fall out of suspension or settle to the bottom of the fermenter.
Lower Alcohol Content in Cold Brewed Beer
Another interesting aspect of beers that are cold brewed is they typically have a lower alcohol content. Next time you visit your beer store or craft brewery if they have lagers on tap take note and you will see most hover around the 5% ABV mark whereas it is not unusual to see ales running close to 8% ABV.
The lower alcohol content is partially a result of the cold fermentation process the lagers go through. To understand the reason for this you need to understand a bit about the fermentation process itself.
As a beer ferments the yeast is eating the sugars within the wort. A by-product of this process is not only alcohol being created but also CO2, as well as the beer’s distinct flavor and aroma being developed. Warm fermentation results in the yeast coming alive and very active resulting in them consuming all of the sugars at a very fast rate which results in higher alcohol levels and the production of certain flavors and aromas.
When you brew a beer using lager yeast and at lower temperatures, the yeast converts the sugars at a much slower rate, this results in less alcohol and off-flavors being created as well as producing a much cleaner tasting beer.
Advantages of Cold Brewing Beer
Cold brewed beers have many advantages over their warmer brewed cousins. Brewing at lower temperatures produces less extensive off flavors. As a result, these beers tend to have the following desirable traits:
- A clearer, much lighter appearance.
- Lower alcohol content or ABV
- They will typically have a smoother more crisp flavor
- Their head retention or foam is typically more pronounced.
- They usually have a much more mellow taste
The Importance of Cold Brewing Lagers
Brewers are notorious for experimenting with recipes and brewing techniques in an attempt to develop new styles of beers. While many brewers have made beers using lager ingredients and ale yeast with good results, many have attempted to ferment lagers using lager yeast at higher temperatures with the end result not being ideal.
In most cases, you will end up with higher alcohol content as well as higher amounts of ester production, which along with the reduction in the number of proteins that would typically have dropped out of suspension results in negative flavor profiles being created.
Guide to Cold Brewing Beer
If you want to get a full overview of how to lager beer check out that post; however, the following is a quick overview of the process.
Step 1 is to brew your beer as you usually would. Although you can use an ale recipe we recommend you source out a good lager recipe to use. We provide one further in this post.
Step 2 let your beer start to ferment at room temperature. As soon as you see activity in your fermenter move it to a cold fermentation chamber to begin the cold brewing. Strive to ferment it between 48 – 55 degrees Fahrenheit. Let it ferment in this environment for 3 – 5 weeks.
Step 3 is where you will get rid of some of the off flavors that are natural to the fermentation process. The yeast if allowed to will clean these flavors up. The best way to do this is to bring the yeast back alive by raising the temperature to 60 – 65 degrees Fahrenheit, for 24 hours to 48 hours.
Step 4 is the lagering stage. Slowly lower the temperature of your beer down to 35 – 40 degrees Fahrenheit and leave it there for 3-4 weeks.
Step 5 is to bottle or keg your beer as you usually would.
Cold Brewed Beer Recipe
The following is a lager recipe you can try using the instructions provided above.
Batch Size: 5 Gallons
Estimated OG: 1.051
Estimated FG: 1.009
IBUs: 29
Estimated ABV: 5%
Brewhouse Efficiency: 70%
Boil Time: 90 mins
Malt/Grain Bill
11 lbs Pilsner
6 oz Crystal 10L
8 oz Carapils (dextrin malt)
Hops Schedule
1 oz Perle (60 min)
1 oz Saaz (5 min)
1 oz Saaz (1 min)
Yeast: Fermentis – Saflager – German Lager Yeast S-23
The Final Word
Cold brewing beer is simply another term for brewing a lager. If you have never brewed one before we recommend you give it a try. Many people shy away from doing so because they believe it is much more complicated than brewing an Ale. Although it does require the ability to ferment at lower temperatures that can be as simple as picking up an old refrigerator or freezer and attaching a temperature controller like an inkbird to it. Outside of that, the process is very straightforward.
P.S. If you are looking for some recipes to brew be sure to check out my offer to get my top 5 recipes from my brewpub. Details are on the side of the blog or bottom if you are on your smart device.