Lagering 101 By: Love2brew

Over the past few months I have personally spent time at the store reviewing the differences between ale and lager fermentation with a number of customers looking to learn more about this process and create some awesome lager brews.  I thought it would be a great topic to scratch the surface on and then allow our content writers to touch upon deeper in the future.

Before we dive into the differences in practice let’s take a moment to understand the differences between an ale and a lager.  The word “lager” is derived from the German word “Lagern” which translates “to store”.  Lagers tend to have a more critical guideline to what makes a great lager “great”; basically lagers should be very “clean”, a clear malt character without off flavors such as diacetyl, fusel alcohols, esters, etc.  With ales brewers may be able to get away with some of these off flavors but a lager beer is well known for its clean and crisp profile.  Some popular commercial examples are Sam Adam’s Boston Lager, Brooklyn Brewery’s Brooklyn Lager, Anchor Steam flagship brew, and of course the big three American Light Lagers. 

When brewing a lager there are three main components that will change in your process when comparing the process to brewing an ale, they are yeast, temperature, and time.   Lager yeasts will naturally produce less fruity esters when compared to many ale yeasts.  In addition the give off a strong sulfur smell (rotten eggs) during fermentation so if this is your first time brewing a lager please re-read this sentence!  Don’t stress about infection in your batch and definitely do not dump your brew.  These smelly compounds will be eventually processed by the yeast and the result will be a delicious, rotten egg free beer.  Lager yeasts also ferment from the bottom of your fermenter so do not be surprised if the activity is visibly different when compared to watching your ales go berserk in your carboy.

The majority of Lager yeasts need to be fermented at lower temperatures and because of that the yeast often works a little slower when compared to ale yeasts thus lengthening the fermentation time needed both in your primary and secondary ferementer.  As with any beer you decide to brew there are multiple factors that will influence the length your fermentation and conditioning time.  As mentioned earlier the goal of brewing a lager is to produce a clean, malty, refreshing brew so while there are methods that may be used to shorten fermentation time we will remaining primarily focused on the lager process without shortcuts. 

Temperature during lager fermentation is a very important factor that will impact the flavor and clarity of your beer.  Your primary fermentation should be done at a range of 45-55°F (7-13°C).  This cold temperature is designed to prevent the creation of fruit-like esters by your yeast.   These cooler temperatures require a longer conditioning phase for the beer to ferment properly; should you choose not to allow your yeast to fully condition you risk off flavors and aromas such as diacetyl.   These cooler temperatures are also responsible for your brew’s clarity; the cold temperatures will cause the proteins that contribute to haziness in your brew to settle out during fermentation.

Next comes the Lagering phase itself.   The lagering phase is designed to really bring a crisp clarity and smoothness to your beers.  Regardless of the yeast you’re using you should be sure to check the instructions on the package for the fermentation temperatures recommended.  Once your primary fermentation has settled you will need to rack your brew to a secondary fermenter.  The temperature you lager at will be dependent on the temperature you fermented at; typically you want to aim for 10-15°F (5-8°C) lower than what your fermentation temperature was.   According to John Palmer’s How to Brew the recommended lagering times are one of the following (keep in mind that higher gravity beers will need to be lagered longer):

·         4 Weeks at 45°F (7°C)

·         5-6 Weeks at 40°F (4°C)

·         7-8 Weeks at 35°F (2°C)

With this information handy you may choose which method will be best for you.  If you have the time and patience I personally recommend the 7-8 week method at 35°F (2°C) but I know your passion for beer all too well and sometimes we simply cannot wait.  It also goes without saying that you will need some sort of temperature controlled unit to regulate these temperatures.  We suggest using a spare refrigerator, ice chest, or kegerator although there are people out there who have constructed their own methods that have worked very well also.

That wraps up our basic introduction to lagering; as always if you have any questions/comments feel free to post below!  Cheers!