What is Different for Brewing Lager Beer?
Aagh! It Froze!
By the way, what if your beer freezes during lagering?? Horrors!!Well, it happened to me. Let me tell you about my first lager...
'Twas a few weeks before Christmas and all around the house, not an airlock was bubbling, in spite of myself. My Vienna was lagering in the refrigerator out there, with hopes that a truly fine beer, I soon could share.The Airstat* was useless, 32F couldn't be set, so I turned the 'fridge to Low, to see what I would get. On Monday it was 40, On Tuesday lower yet, On Wednesday morning I tweaked it, seemed like a good bet.
Later that day when I walked out to the shed, my nose gave me pause, it filled me with dread. In through the door I hurried and dashed, when I tripped on the stoop and fell with a crash. Everything looked ordinary, well what do you know, but just in case, I opened the 'fridge slow.
When what to my wondering eyes should appear, My carboy was FROZEN, I had made Ice beer! My first thought was tragic, I was worried a bit, I sat there and pondered, then muttered, "Aw Sh##!"
More rapid than eagles, my curses they came, and I gestured and shouted and called the fridge bad names. "You Bastard! How could you! You are surely to blame! You're worthless, You're scrap metal, not worth the electric bills I'm paying! To the end of the driveway, with one little call, They will haul you away, haul away, haul away all!"
Unlike dry leaves that before the hurricane fly, when brewers meet adversity, they'll give it another try. So back to the house, wondering just what to do, five gallons of frozen beer, a frozen airlock too. And then in a twinkling, I felt like a goof, the carboy wasn't broken, the beer would probably pull through.
I returned to the shed, after hurrying 'round, gathering cleaning supplies, towels, whatever could be found. I'd changed my clothes, having come home from work, I knew if I stained them, my wife would go berserk. I was loaded with paper towels, I knew just what to do, I had iodophor-ed water and a heating pad too.
The carboy, how it twinkled! I knew to be wary, the bottom wasn't frozen but the ice on top was scary! That bastard refridge, it had laid me low, trying to kill my beer under a layer of snow. I cleaned off the top and washed off the sides, picked up a block of ice and threw it outside. I couldn't find the airlock, it was under the shelf, and I laughed when I saw it, in spite of myself.
The work of a half hour out there in the shed, soon gave me to know, I had nothing to dread. The heating pad was working, the ice fell back in, I re-sanitized the airlock, I knew where it had been. Not an Eisbock, but a Vienna I chose, it was the end of the crisis of the lager that froze.
I sprang to my feet, to my wife gave a whistle, and we went off to bed under the down comforter to wrestle. But the 'fridge heard me exclaim as I walked out of sight, "Try that again, you bastard, and you'll be recycled all right!"
Should I Add More Yeast?
When your lager freezes, chances are the yeast has been impaired. If you are towards the beginning of the lagering cycle, then there may not be enough yeast activity after it thaws to properly complete the attenuation and condition the beer. You should probably add new yeast. If you are at the end of the lagering cycle, and were planning on priming and bottle conditioning it, then you should probably add more yeast also. If you are planning on kegging it and force carbonating (like I was), then you don’t have to worry about it. I say “probably” because some yeast will survive. Even if the beer freezes completely for a short time, typically 20% of cells will remain active. The questions are: 20% of how many, and just how active? Therefore, you should probably add new yeast.
The yeast you add to the fermenter should be of the same strain as the original yeast. If you are using yeast from a ready-to-pitch package, then that quantity is probably sufficient and you can pour it right in and swirl it around to mix it evenly. Because you are not trying to conduct a primary fermentation and are not concerned about a fast start, you do not need to build up the count any further, nor do you need to acclimate it to the lagering temperature first. The yeast will acclimate over several days and finish the fermentation cycle.
If your yeast came from a small smack-pack or slant, then you may want to build up the cell count by pitching to a starter wort first. And you may want to conduct that starter at your primary fermentation temperature to help the yeast acclimate to the lagering cycle. As noted above, these steps are probably not necessary, but it never hurts to stack the odds in your favor. You can either pitch the starter at full krausen or wait for it to ferment out before adding it. The small amount of primary fermentation byproducts that you add to the beer by pitching at full krausen will not affect the flavor significantly.