On Brewing Lagers

On Brewing Lagers

Can I brew a lager? Yes you can!

Homebrewers sometimes tend to look at lagers and conclude that it’s outside of their brewing comfort zone and skip right over them. We’re here to tell you that it can be done with a little time and effort (and some cold storage). More than likely the very first beer you ever tasted was a lager. The large breweries that dominated American beer in the 20th century were mainly started by German immigrants who brought their lager beer recipes with them, and then modified them to use more readily available (and cheaper) ingredients like 6-row malt, corn, and rice. 

The main difference between a lager (Saccharomyces pastorianus) and an ale (Saccharomyces cerevisiae) is the yeast you use to ferment. Ale yeasts are typically fermented between 68˚F and 72˚F with some strains able to ferment up to 95˚F (Saisons and Kveiks). Most beer styles are ales as they were originally wild yeasts that were domesticated by brewers over time through selective pressure (i.e. picking the yeasts that produced the most desirable results and propagating only those yeasts for future brewing). Ales are considered “top fermenting” yeast. They ferment and condition very quickly and they tend to produce a variety of flavors (e.g. esters and phenols). Ales are perfect for homebrewing since they can ferment at cellar temperatures with little concern.

Lager yeast (Saccharomyces pastorianus) on the other hand, works best when fermented cool. The typical lager fermentation range is around 50˚F but there are some strains that work well up to 65˚F. Lager yeast are considered “bottom fermenting” and since they are fermenting cool, their metabolism is slowed so fermentation takes longer. Lagers have a unique “crisp” clean flavor that cannot be achieved with ale yeast, due to the fact that lager yeast often finishes with a lower gravity than ale yeast. Lager beers are mostly associated with pale malt bills and very light beers like Pilsners, Light American lagers, and Mexican lagers. Pale beers are not the only thing one can make with a lager yeast though, as there are lots of other styles that are traditionally brewed with lager yeast, like Vienna Lager, Marzen, Schwarzbier and Baltic Porter just to name a few. 

Key differences between fermenting Ale vs. Lager

Fermenting a lager does require having a dedicated cold storage area for your beer. Most people will use a freezer with a temperature controller like an Inkbird hooked up to it so you can dial in the exact temperature you’d like to ferment at. 

While ale yeast condition quickly (conditioning being the metabolizing of fermentation off-flavors) lagers don’t metabolize very fast. This is why after you have reached about 75% of your primary fermentation it is a good practice to then slowly warm your lager up to room temperature for a diacetyl rest for 3 to 5 days. Why is this necessary? To get rid of flavors you don’t want! Diacetyl is a chemical compound created during fermentation that has a very buttery flavor and aroma. It is most commonly used as a fake butter flavor on popcorn in movie theaters and provides an unctuous, unreal flavor - it’s not what you want in your beer. By warming up your beer, the yeast speeds up and can condition out any diacetyl created during fermentation. This step also helps to dissipate any sulfur aromas that may have got trapped in the beer as well. Your beer should reach terminal (i.e. finishing) gravity during the diacetyl rest.

After the diacetyl rest it is then time to actually lager your beer before packaging. The word lager comes from the German word lagern which means to store. Most brewers will rack (transfer) their beer into a sanitized secondary container before lagering and then slowly chill the beer down to the mid 30’s Fahrenheit. This allows any precipitant to drop out of solution and clear your beer. This process can take up to 5 weeks. 

As a homebrewer, I personally do not rack my beer off during the lagering process to avoid oxidation and/or contamination and my personal experience has shown that there is no significant flavor difference between a beer that has been racked and one that hasn’t, so there’s no need to rack at home. Additionally, even though the yeast is colder than fermentation temperature during the lagering stage, there is some evidence that the yeast will continue to condition the beer, albeit slowly. 

After 5 weeks or so you can keg and carbonate (or bottle) your beer as usual. I recommend to people that are bottling conditioning their beer to prime and bottle the beer right after the diacetyl rest, while the beer is at room temperature. That way you still have yeast that are active to consume the priming sugar for carbonation. Let the bottled beer sit at room temperature for 2 to 3 weeks until it is carbonated and then stick the beer in a fridge and let it sit for 4 to 5 weeks to lager. If you lager before bottle conditioning you will need to warm the beer before bottling and add a gram or two of dry yeast along with your priming sugar as you will have little to no active yeast left in the beer for carbonation.

This all may sound like a lot, but it is worth it. Some people will use warmer fermenting lager yeast like Fermentis 34/70 which will give lager characteristics up to 65˚F. You just need to ferment a little longer at this temperature and not worry about a diacetyl rest since it’s already near ale temp anyway. One thing about fermenting lagers a little warm you may get some ale like ester flavors. Maintaining a steady fermentation temperature is key to a good lager fermentation. 

So don’t be afraid of making a lager! It takes a little more time and attention to fermentation temperature but the results are worth it. Please check out our lager recipes and feel free to contact us with any questions.

Keep it cold,

John L. & John H.