by Greg Hackenberg
You want to brew a lager. You have a fermentation chamber or vessel with good temperature control. You’ve brewed up a tasty wort and are ready to ferment.
For decades the accepted method has generally been the following. Cool wort to ale range and pitch yeast, gradually cool to lager range and ferment for about two weeks. Some will cool to lager range before pitching and some add a diacetyl rest at the end, raising the temperature to ale range for the last few days. With fermentation complete, start ramping down the temperature 5d or so per day until you get as close to 32o as you can. Rack to secondary and lager at around 32o for at least four weeks and up to six months. The beer will clear, off flavors from the yeast will be eliminated, and the overall flavor will round out.
Maybe you don’t want to brew a lager anymore. There are problems, and not just with the wait time, the equipment and the space that will be unavailable for other things. In commercial brewing the ramp down to lager temperature is highly controlled to keep the yeast active throughout. This is difficult to reproduce in a homebrew setting, as yeast can easily be shocked into dormancy during the chilling. Dormant yeast is not cleaning up anything.
But there is a better way, and it is not so new. It’s known as accelerated maturation in commercial brewing. I’ve been successfully using a ‘Fast Lager Method’ as laid out in a Brulosophy post from 2018 (sources listed below). So, here’s what I do.
1. Build a yeast starter. Lagers need a good dose of healthy active yeast. Make the starter the day before, you want fermentation to still be active when you pitch it.
2. Chill the wort to lager range. I generally shoot for 52o and pitch.
3. When the ferment is 50 percent complete, raise temperature 5o to 57 oF When the ferment is 75 percent complete, raise to 62 oF When the ferment is 90 percent complete, raise to 66 oF and hold until at terminal gravity.
4. Ramp down the temperature 5 degrees per day to 32o and hold for a couple of days. That’s it. You do not need an extended lager, because…the yeast have done the job already. Carb and serve at your leisure.
Yes, it works. And it works because of Science! Here’s an article by Denny Conn citing John Palmer who explains it:
“Yeast have three phases in their life cycle: Adaptation, high growth, and stationary…They do not have a maturation phase where they clean up byproducts…Byproducts can be consumed at any point during the high growth phase, but they are a lower energy source than sugar, so guess what? Byproducts are not a biological priority. The brewer therefore needs to plan his pitching rate and fermentation conditions such that the yeast run out of fermentable wort sugar before…they go into stationary phase. Now you have a majority of vigorous yeast… the sugar is gone, and they are still hungry, so they turn to acetaldehyde and diacetyl as alternate energy sources and maturate the beer.”
“Basically, it’s like this: Once fermentation has reached the first half (or so) of the expected total attenuation, you can start raising the temperature to speed fermentation without experiencing detrimental effects on the beer.”
Note that 75% of the fermentation is conducted in roughly lager range, only that last 10% is in true ale range. You have to do a little math: OG-expected FG=total drop, then x .50, .75, .10 for the gravity steps.
Then there is the monitoring of the gravity. Now I have a fancy pants Tilt hydrometer that gives me gravity via Bluetooth to my phone. You can take samples and make periodic checks along the way. But you can also go seat-of-the-pants and go the percent of fermentation based on the following estimates of fermentation times. Or a combination.
Fermentation Recommendations:
OG of Wort: ≤ 1.060, Yeast Type: Liquid, Approximate Primary Time: 4–7 days
OG of Wort: ≤ 1.060, Yeast Type: Dry, Approximate Primary Time: 5–8 days
OG of Wort: ≥ 1.061, Yeast Type: Liquid, Approximate Primary Time: 6–10 days
OG of Wort: ≥ 1.061, Yeast Type: Dry, Approximate Primary Time: 7–14 days
It’s worked great for me. Quicker turn around, and no off flavors. Give it a try. You might just start brewing more lagers.
Sources:
https://brulosophy.com/methods/lager-method/
https://byo.com/article/fast-lagers/
http://braukaiser.com/wiki/index.php/Fermenting_Lagers
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