Chapter 11

Priming and Bottling

Priming and Bottling Lager Beer

Ninety five percent of the time there is no difference between priming for lager beer and priming ale. Fermentation is a function of the yeast - they work better when they are warm, in other words, in their preferred fermentation temperature range. After the majority of fermentation is complete, the yeast activity will slow down and raising the temperature a few degrees (a diacetyl rest) can help keep the yeast active to fully maturate the beer, eating up the diacetyl and acetaldehyde. After fermentation, the beer can be chilled to near freezing temperatures to help clarify the beer. This is the actual lagering (storage) step. The beer will be best if it is fully fermented and maturated before lagering. Therefore, you probably should prime and bottle before lagering. 

If you are kegging and force carbonating with a CO2 tank, then you can proceed directly to lagering from maturation, and carbonate the beer after lagering (or during). But if you are priming for carbonation, do that first before lagering. Lagering is a non-yeast activity, a physical clarification of the beer facilitated by cold temperatures.

But once in a while you will need to add fresh yeast for priming and carbonation purposes. This is most common when the beer is given a long cold fermentation for more than a couple weeks. If the beer is very clear at bottling time, then the majority of the yeast may have settled out and there may not be enough left to carbonate the beer in the bottle. Prepare some fresh yeast of the same strain and mix it with the priming solution when you rack the beer to the bottling bucket. You will not need as much as you originally pitched to the wort, typically 1 yeast package (about 100 billion cells) or only about 1/4 - 1/2 cup of slurry for 5 gallons.

Don't worry about priming and carbonating the lager beer at room temperature – the percentage of sugar that is being fermented for carbonation at this stage is so small that the added difference in taste is unnoticeable. The reason for doing it this way is to avoid thermally shocking the yeast and to speed up the carbonation time. 

Note: This page has been updated to reflect the better information found in the 4th edition (2017, Brewers Publications).