Most of us grew up with them, many may have disavowed them for a while . . . but fans of beer know that lagers come in many colors and strengths and that they are often considered the apex of brewing. Lagers will put on display a brewer’s skills in both the brewhouse and the cellar as the recipes are often simple, but the techniques to brew them require a delicate touch and planning.
In this piece the goal is to show you that even with basic equipment and some sound processes brewing a solid lager is not out of reach for even beginner brewers. Special attention to a few details as well as patience should yield a lager to be proud of. But before we get into that, know that the term “lager” has come to have two connotations in modern brewing. So the first section will be focused on clearing up that confusion.
Yeast or Conditioning?
The term lager, when used in reference to brewing, goes back to beer brewed in the central European regions of Bohemia and Bavaria. In these regions some beers were allowed a slow and cool-temperature aging process performed in underground cellars. These beers were referred to as lagers since the Germanic word means “to store.” Prior to the 1500s, brewers in these regions would have primarily been using Saccharomyces cerevisiae yeast for their lagers. But a freak event occurred early in the 1500s where S. cerevisiae mated with a New World yeast species called S. eubaynus, which came from the cold-temperate region of Patagonia in South America. The cross created a new hybrid species: Saccharomyces pastorianus. This new yeast began to spread through the highlands of central Europe through the century and brewers found it performed quite well even fermenting in these cool, cavernous locations. So while the lagering process can actually be performed on beers fermented with any type of yeast, the term later became synonymous with any beer fermented with this “new,” clean-fermenting species of yeast.
Lagers: The Yeast
One of the main hurdles to brewing beer with Saccharomyces pastorianus is the fact that many of its strains are well known to create off-flavors if fermentation temperature gets too warm. Many of the strains are best fermented between 50–56 °F (10–13 °C) and require brewers to either have a dedicated temperature-controlled space or an expensive glycol unit for chilling the fermenter. But not all S. pastorianus strains are like this. There are several, notably California common and Weihenstephaner W-34/70, which can produce clean beers even when fermented up near room temperature (low-to mid-60s °F or high teens °C).
If your living arrangement does not offer a cool basement or space for a dedicated fermentation chamber, then a swamp cooler is one alternative to keep fermentation temperatures below ambient room temperature. But there are many inexpensive, MacGyver techniques homebrewers have used to keep their lagers cool during active fermentation. A quick web search can yield some interesting results. Also be sure to pitch double the amount of yeast you would for your ales . . . so for example, two sachets of yeast instead of one for that Pilsner.
Lagers: The Process
In order to clarify the terms, many brewers now call the lagering process either cold-conditioning or simply conditioning. As a homebrewer the simplest way to lager beers is in a refrigerator or freezer that has an external temperature-controller. These temperature controllers can be found at many homebrew supply stores. The lagering process can be performed in a wide range of temperatures, but is generally done in the 30–50 °F (-1–10 °C) range. The beer should be completely finished with primary fermentation, moved off the yeast before lagering starts, and should be in a vessel that is either filled right up to the very top (if using a carboy) or in a sealed and CO2-purged container (like a Corny keg).
The time frame for lagering can be as short as one week and as long as 6 months or more for bigger beers. Just note that the warmer the lagering temperatures, the less time a brewer should condition the beer as excessive aging in warmer temperatures can be detrimental, especially to more delicately flavored beers like a helles. Meticulous brewers will slowly ramp down the temperature over the course of a week or more to get the beer down to lagering temperatures. If you don’t have this luxury, just be sure air is not sucked back into the vessel.
Finally, it is important to note that the beer should be clean going into the lagering process. Lager yeast fermented cold may have trouble cleaning up an off-flavor called diacetyl. A brief warm up prior to lagering called a diacetyl rest, is common to assure cleanliness. Lagering is simply a time for settling and mellowing of flavors.
Another key to producing a quality lager is to reduce oxidation during transfers. One of the best ways to do this is to obtain a carbon dioxide tank and regulator to purge any receiving vessel to minimize oxygen pick-up. When post-fermentation beer gets even minute amounts of oxygen absorbed, both the fresh malt and hop character quickly fade. Focus your attention on these details and you should find yourself sipping a lager to be proud of.