Lager Fermentations: Tips from Pros

Brewer: Randal Sprecher, Owner and Founder of Sprecher Brewing Company in Glendale, Wisconsin.

The styles of lager we brew at Sprecher tend to be German/Southern Bavarian styles, which are my first love. I spent 18 months in Germany while I was in the military and lagers are the principal beers there. Our Black Bavarian is a true Kulmbacher lager (although it is now usually categorized under the dark lager category). Some of the other lagers we also brew include a Vienna style lager, which is our biggest seller. We also make an Oktoberfest, a maibock and a Munich dunkelbock, and last year for summer we softened our Lake Michigan water to brew a proper Czech Pils.

Sprecher’s lager yeast is a Weihenstephan lager culture, and we use that for most of our lagers (although not all). I started as a homebrewer back in 1971, and back then I brewed with a yeast strain that I had brought back to the US from my time in Germany. When I went to UC-Davis later on, I learned a lot about yeast culturing. After that, when we opened the brewery, I used to maintain our in-house cultures. That grew more difficult as time went on, so we  found a yeast supplier to maintain our strains for us.

If you want to run a good lager fermentation it is absolutely paramount that you pitch enough yeast. You cannot get the right profile at the lower fermentation temperatures if you don’t have enough yeast. The percent of daughter cells in your culture — which are young budded cells — is the most important thing to have in order to create the right character and bouquet. You want to have about 20 to 30 million cells per milliliter. You can’t really know how many cells you have in your culture without a microscope, however. I used to do a lot of lab work as a homebrewer, but that may not be something that every homebrewer can do. If you can’t perform the extra lab work, however, always start any lager fermentation with a well-oxygenated starter culture.

This is true for all fermentations, but temperature control is the other most important part of a successful lager fermentation. If you really had the right thing going in your homebrewery you’d be lagering in the low 40s Fahrenheit (4–6 °C), but that would be pretty slow going. Fermenting in the mid 50s (11–12 °C) is more realistic. It is very difficult at home maintaining a plus or minus one degree, which is what commercial brewers do. If you live in the right environment you can try to find an area of your house to keep the temperature constant, such as the basement. For example, here in Wisconsin we are lucky to hit 45 °F (7 °C) on some days. If you can afford it, you can also use temperature control devices to help maintain fermentation temperatures. For example, you can put on/off devices in the circuit of the plug to a refrigerator dedicated to fermenting beer to keep the fridge in the right temperature range.

Beyond yeast and temperature control, however, when you brew lagers it is also important to make sure to get a good break of the wort after the boil to get as much of the trub away from the yeast as possible in order for the yeast to do a proper job. Also, try to rack off the clear wort on the top of the fermenter as it gets down to your pitching temperature. Get rid of as much of that protein as you can before pitching because it does get in the way of a good clean fermentation.

Brewer: David Berg, Assistant Brewmaster at August-Schell Brewing Co. in New Ulm, Minnesota.

At August-Schell we brew several lagers, including Pils, Vienna (Firebrick), bock, Maibock, Oktoberfest, a hoppy rye lager (Emerald Rye), and a smoked black lager (Chimney Sweep).

We have two primary in-house lager strains, one that dates back to the Christian Schmidt Brewery and the other to the Schaefer Brewery. We also occasionally use additional strains for limited-release beers. It’s very important to have an adequate amount of healthy yeast for brewing any style of beer. When brewing lagers, you need a higher pitch rate than for ales. Whereas an ale may have a pitch rate of 0.5-1 million cells per mL per degree Plato, we pitch our lagers between 1.5-2 million cells per mL per degree Plato.

Fermenting lagers is really no different than fermenting ales; to be successful you need a wort that has the adequate nutrients and oxygen, an appropriate amount of healthy yeast, and a way to control the temperature. Modern breweries have tanks with cooling jackets that allow flow through the jacket based on beer temperature. This was not always the case, however. You can control fermentation temperature fairly well by controlling the room temperature. Another option is fermenting in a modified refrigerator or freezer.

The two most common mistakes brewers make when making lagers are not pitching enough yeast and fermenting too warm. The former is easily avoided; the latter can be solved by either equipment (a converted freezer, for instance) or by fermenting in a cold room during the winter. There is no reason to be intimidated by brewing lagers. While the nature of the styles make them less forgiving to errors in pitch rates and temperature control, these problems can be overcome with planning.

Written by Betsy Parks