Lager is derived from the German word “lagern,” which originally meant “to store.” The original style of beer was created through long-term storage in deep underground caves. While a typical ale can be brewed, bottled, and consumed within two to three weeks, Lager beer requires weeks or even months to mature. As the temperature decreases, the metabolism of most organisms slows down, including yeast cells.
To successfully brew beer, it is crucial to allow each stage of fermentation and conditioning to proceed at its own pace. Rushing any part of the brewing process increases the risk of off-flavors, which are considered defects in the final beer.
If off-odors develop in Lager beer, it’s best to wait a few more days before bottling. Additionally, Lager beer may exhibit unusual aromas during fermentation, such as sulfur characteristics. With time, these characteristics usually dissipate, leaving a clean, finished beer. Patience is required when storing Lager beer to allow it to fully develop.
Control the Fermentation Temperature
Each yeast strain has an optimal temperature range for fermentation. Most yeast strains perform best between 38°F and 60°F, depending on the specific strain. It is crucial to maintain the fermentation temperature within this range once the optimal performance range for a particular yeast strain is determined. Using a stick-on thermometer in the fermentation tank makes it easy to monitor the temperature.
The most accurate temperature control method is using a controlled storage cabinet converted from a refrigerator or freezer into a fermentation tank. However, most yeast strains have an optimal fermentation temperature range outside the normal range of these devices. Therefore, additional temperature control devices must be used to ensure accurate and reliable operation at higher temperatures. These temperature control devices are widely available and come with complete instructions.
Winemakers who do not have dedicated temperature control devices can still employ appropriate temperature control methods. Beer brewing predates modern refrigeration technology, so placing the fermentation tank in a cold location like a basement or garage is an option. In hotter areas, brewing during colder winter months may be necessary. However, it is important to remember that air temperature changes much faster than liquid. It is also essential to protect the fermenter from direct sunlight and use a lid for insulation. While daily temperatures may fluctuate by 20-30°C, the fermentation tank’s temperature will only fluctuate by a few degrees Celsius within the same period, which is within an acceptable range for most yeast strains.
Use Lager Type Yeast
Today, brewers have access to a wide variety of high-quality yeast strains. Using a liquid yeast strain or culture at the appropriate fermentation temperature is the best option for brewing authentic Lager beer. Although these yeast strains are more costly than dry yeast strains, they generally yield better and more consistent results, especially for beers requiring lower temperatures.
Liquid yeast strains offer excellent purity and performance, with different strains available to produce specific Lager styles. Most yeast suppliers provide information on the optimal fermentation conditions for each strain. Even brewers in remote areas can obtain high-quality liquid yeast strains through mail order.
Use a Yeast Starter
When brewing Lager beer, using a yeast starter is crucial, even when using liquid yeast strains. As the fermentation temperature decreases, yeast metabolism slows down significantly. During the critical growth stage after inoculation, yeast cells multiply to ensure sufficient yeast for fermentation. Lowering the fermentation temperature can prolong the yeast’s growth stage, potentially leading to extended fermentation times, bacterial contamination, and off-flavors.
To avoid this problem, it is recommended to inoculate with a larger amount of yeast, typically two to three times the amount required for ales. The best way to achieve this is by adding healthy yeast slurry from a previous batch or by creating a yeast starter before brewing.
Use Irish Moss During Wort Boiling
Protein is the main contributor to beer turbidity. Extended contact time between beer and protein residues (sediment) in the fermentation tank can result in off-flavors. This is especially critical for Lager beers, as they undergo a longer fermentation time than ales, and the lower temperatures used can cause protein precipitation. Adding clarifying agents such as Irish moss during wort boiling helps proteins to precipitate and prevents them from entering the fermentation tank, thus improving the clarity and cleanliness of the final beer.