When fermenting a lager, what temperature should it be held at for best results?
This is what I am doing...
- Ferment at 50F.
- When the beer is 60% attenuated allow the temperature to rise to 59F.
- Leave at this temp for 48 hours for a diacetyl rest.
- Rack to a secondary
- Slowly bring the temperature of the beer down. 4F per day
- Once at lagering temperature (mine is 35F), leave it alone for 20 days.
- After 20 days, taste it, if it doesn't taste right I'll give it another week. When it tastes clean, I keg it.
There are many different ideas on which temperatures to use. You could ferement even lower, it will just take longer, warmer and it will be quicker but could produce esters. The diacetyl should be no more than 9 degrees above fermentaion temperature.
Ester production and the need for a diacetyl rest are based on yeast strain. You may not need either.
"Best results" really depend on your taste (or the judge's if you plan on entering competition).
Check with the supplier. WYeast and White Labs list preferred temperature ranges for all their strains. Most lager strains like 50° to 60° F. Many lagers also benefit from a diacetyl rest - raising the temperature to the high 60's F near the end of fermentation.
Like ales, there is much subtlety surrounding lager fermentation. Higher temperatures produce more esters, usually inappropriate in lagers. On the low end of the range the resulting beer is "cleaner".