Pressure ferment lager starting cold, how much yeast

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Apr 6, 2024
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Just got my 55 liter Fermzilla Tri-conical and are planning a lager for the first batch.
According to this Kegland blog post you should optimally start a lager fermentation at regular lager temperatures for the first 24h without pressure, and then ramp up temperature and pressure.

The question is, if I start cold, do I need to pitch the same amount of yeast as a traditional cold lager fermentation, even if the temp goes up after 24h ?
Or are people simply starting warm with no ill-effects ?
I pressure ferment lagers at tradition lager temperatures @ 50F (10C). I don't let them rise in temperature very much. I pitch at 0 psi and let the pressure build to 7.5 psi, toward the end I let the temperature come up to 54-55F (12.5C) and start spunding at that point. Using this method I definitely pitch the same amount of yeast. This pressure method reduces the yeast growth, which in turn reduces ester formation. Pitch rate at lager temperatures should be 22-33 grams of dry yeast per 5 gallons (19 liter).

They state to keep the pressure at zero for the first 24 hours, as it promotes yeast growth. I don't do that, I just let the pressure rise on it's own with the fermenter sealed, the PRV is set to 7.5psi. You could leave the temperature low, it produces some really nice clean lagers, but it would take longer.

Or you could just pitch at 62F (16.5C) and let it go. If you go the warm route, you can reduce the pitch to about 1/2. The higher the temperature, the higher the pressure. I would raise the pressure to 15 psi at those temperatures.

I have fermented both ways and I prefer the colder method, but it takes just as long as a traditional lager. The warmer temperatures and higher pressures speeds everything up considerably and the beers turn out really nice. I just prefer the colder method because the beer has an authentic lager profile. If you're on your first try at this, I would pitch at 10C and let the pressure rise naturally to 15 psi. The pitch rate should be @ 11-16 grams per 5 gallon (19 liters) if you are using dry yeast like 34/70.

Good luck and happy brewing!

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