Once the beer has been fermented, so when the fermentable sugars have been converted into alcohol and carbon dioxide, we can lower the beer. We are now going to cool the beer to 0 - 4 degrees Celsius.
The word lagering comes from the German "Lagern", which means to store. We store the beer in stainless steel tanks. Lagering is a kind of maturation where the beer is improved in aroma, as it were.
Lagering is especially important for bottom-fermented beers. These beers must ferment dry and crisp and must have an aroma that is as "clean" as possible. In the past, these beers were aged for up to 3 months. Due to better techniques and also cost savings, that has now been reduced to 4 weeks.
At these cool temperatures, the fermentation process will slowly stop and the yeast cells will sink to the bottom. This is therefore the first purpose of lagering, allowing the yeast cells to settle, stopping the fermentation process and saturation with carbon dioxide.
During the lagering process, residual sugars are initially converted by the yeast to mainly carbon dioxide. The beer is now naturally saturated with carbon dioxide.
Proteins that have become associated with phenols from the hops and grains during the boiling of the wort can now also precipitate. This is very important for the clarity of the beer. These proteins could otherwise cause cloudiness in the beer.
In addition, we want to get rid of certain odors that have arisen during fermentation and are not wanted in the end product, the so-called off flavors. We think of diacetyl, which is reminiscent of butterscotch. We also get rid of acetaldehyde, which reminds us of green apples. There are many more components that we lose in this way and this all contributes to a better balanced beer with finer aromas.
We can also add other flavors to the beer during the lagering process. Think of ripening on fruit. Kriek, for example, is matured on cherries. We can also add flowers. For example, we add hibiscus flowers to our Rose Hipped Hibiscus Dipped Flower Power Funky Sour during storage.
We can also add coffee, cocoa, vanilla and many other spices to give more character to the beer. We add these ingredients to, for example, More Complicated Than Your Girlfriend Stout.
Adding fruit, herbs or other ingredients strongly depends on the style and wishes of the brewer. Personally, I think this is a great time to add color and story to your beer as a kind of artist.
And finally, let's not forget the "Dry Hopping". Especially with IPA beers, this last hop dose is very important. When dry hopping, we add hops one last time. Normally we add hops in the brew kettle when boiling, but now at cold temperatures. This gives us completely different aromas in the beer than during the cooking process.
Nowadays, craft beer brewers are again more aging in wood. The wood also adds aroma substances and we also have to deal with certain bacteria that live on the wood.
On a tour of a brewery, lagering is often seen as a boring process where nothing happens, but the opposite is true. It is a very fascinating process where we have to let nature take its course.
This process is well known for wine aging, but beer aging is still undervalued. By having more insight, we also gain more admiration for the bearing process!