Monday, November 30, 2009

SPAb3 + bringing yeast back from the frosty grave

Brewed Stonington Pale Ale, Batch #3 yesterday.

Though I have 2 cases of the stuff from the October brew session, I can always use more bottles of this beer for gifts, parties, requests, etc. In the interest of CIP intended to incrementally improve the beer, I took the opportunity to tweak the grain bill just a little, using crystal 40 instead of 60, as 60L is usually above the higher threshold for pale ales nowadays. I also upped the crystal addition to 1lb instead of 1/2 lb...the beer is very dry, and perhaps could benefit from just a little more crystal sweetness/body. I also upped the flaked wheat to 11oz (not 12, because that's all that was left...I must have shorted myself at the LHBS).

Aside from that, the grain bill, hopping schedule and yeast remained the same.

Well, except that I pinned my hopes on the fermentation ability of what was to be the first reanimation from the frost-free depths of the frozen yeast bank. If you've been reading along, you'll remember that I started stashing away 25% glycerine saturated 50ml samples in my household, non 80C below bottom rack Kenmore freezer with the hopes of suspending my little wort hungry fungi friends for (much) later use. If you haven't been reading along, then take a look HERE.

Now, when I made the 1056 aliquots, I fully messed up, and didn't decant nearly enough of the resultant beer from the 1000ml starter to end up with a properly thick slurry that is recommended for frozen yeast aliquots. I placed the starter in the fridge for 2 days after signs of fermentation had ceased. The american ale yeast dropped out of suspension pretty well, but since 1056 is such a poor flocculator, as soon as I tilted the Erlenmeyer back to check the flow out of the neck, the yeast had fallen off of the bottom of the flask and immediately resuspended back in to the beer.


And I can't just stick it back in the fridge, and wait another day, as I was leaving the country for a week. So, I figured this relatively low cell count would be the ultimate test for the ability of the yeast to withstand the freezing (and thaw/freeze cycles purported to go on in a household freezer). I suspected the high % of water in this solution could only be detrimental to the possible ice crystal-preventing cryoprotective nature of the glycerine, but I had to press on. I don't know how 'thin' this slurry ended up being, other than to say, I wouldn't normally have otherwise even call it slurry. Working fast to avoid raising their temperature, I stuck the 5 vials in to the freezer, hoping for the best.

Now, these vials have only been in the freezer for a short while, but I figured this would be a good first test to see if there were any viable cells that survived the freezing process, albeit at this low concentration. From this AHA presentation, I gathered that if I get somewhere between 20-37% viability, I would count myself lucky. I took out the sample and let it thaw in the fridge overnight. I made up a 1/4 teaspoon wyeast nutrient+ 100 gram DME/1000ml water starter (likely somewhat large for the quantity of yeast I'd ultimately get from the vial). I thawed the tube upright, so the yeast settled to the bottom of the vial. Huh. Less than 5 mls. that's even worse than I thought it'd be.

I looked over to the smugly full vials of white labs commercial yeast resting comfortably in the fridge door, and I could swear I heard them snickering at my feeble yeast ranching attempt.
Not to be dissuaded, I decanted about 80% of the glycerine/beer liquid diluent, recapped, shook the slurry in to suspension, and pitched it in to the cooled starter. I put it on the new stir plate, and hoped for the best. The stirring action pulled a nice vortex, and was clearly creating an ideal home for this probably frost bitten/hopefully not dead yeast. If this yeast was going to grow, it was going to be in this starter.

Now, I probably looked at the starter every 15 minutes for the next 5 hours, until I went to bed that night. Took a big sniff before I went to bed to see if I could sense any hint of fermentation going on.

Nope. Nothing. And how completely non-turbid that thing looked.

I did, however, wake up to the first gurgles of primordial life asserting itself in this nutrient rich broth. Yahtzee!

Knowing that I started with a really low cell count, I stepped it up by adding another 600ml of 1.040 wort, and another pinch of nutrient. We left the house for a few days to arrive home to a starter busting at the seams. And it smells just like 1056 greedily fermenting starter wort in to beer. I stood there both fists raised in the air. Y'know, like a total loser would do. Well, I'm sorry, but you'll just have to excuse me, as these things make me happy...
So, this past Sunday, I brewed up that SPAb3, using the very healthy and likely large population of reanimated 1056 and the burgeoning and seemingly bottomless bags of hops from my inadequate freezer. I'm still amazed at the pungent aromatics of these 2009 leaf hops from hopsdirect.

The SPAb3 was brewed up without a hitch, and the yeast is happily fermenting her (him?) away now in my undersized fermenter, whose nicely fitting threaded caps were tossed with the rest of the busted 50L Pyrex. Oops.

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