Lager yeast strains are unique, because they ferment wort at temperatures between 45° F and 55° F. Even though they can ferment at these temperatures, they work slower than ales fermented around 68° F. When fermenting lagers at true lager temperatures, you will need to pitch 2 to 3 times more cells than you would when fermenting ales. Our lager strains are supplied in the same pitching rate as our ale strains. Therefore, we recommend doing the following:
To start fermentation at 48-55°F (8-12°C), order two to three times the amount of yeast.
Cool wort to hybrid/ale temperatures (60-65°F/15-18°C), pitch yeast and maintain temperatures until signs of fermentation are evident, CO2 formation or pH decrease. This will take about 24 hours. Begin to lower fermentation temperatures until desired lager temperatures are reached. In order to maintain vitality, it’s recommended to lower 10°F (0.5-1°C) per hour over a 12 hour period.
Use a propagation step. Grow in five to 10 percent of your fermentors final volume (i.e. for a 20bbl, 1-2bbls of wort). Maintain propagation at the same temperature you are going to pitch your yeast. After 24 to 48 hours, add propagation to fermentor.
*After the initial pitch, it’s recommended to use higher pitching rates. Collect two to three times the normal slurry. Perform a cell count, vitality analysis and a microbial stability test on the slurry to determine pitch rate from 1.2 to 2 million cells per milliliter of wort per degree Plato.