Part 1 of this series, we talked about harvesting actual yeast from a bottle of Gulden Draak. In the second and third parts, we talked about growing enough of that yeast to pitch into a wort. In Part 4, we showed the clone beer being brewed.
On Saturday, I pitched yeast that I had harvested from four bottles of Gulden Draak Ale and fed with three separate starter worts to grow its population. The final wort I pitched it into was based on a Gulden Draak clone recipe. As of this writing, the young beer is two days old. This will be my first attempt to truly clone one of my very favorite beers.
While the harvested Gulden Draak yeast was in the starter wort, it seemed to grow very slowly at first, then took off on the second and third starters, blowing through the airlock. That's something I've never had a yeast starter do before. It seems to be following that behavior in the fermenter with the actual wort. It's a yeast that seems to have periods of dormancy followed by periods of rapid activity.
Sunday I saw no activity in the airlock, which I expected because a 2.5 gallon batch of beer in a 6.5 gallon fermenter has a lot of room to work. Late Sunday I saw the fluid level in the airlock shift, implying a bit of pressure in the fermenter. This morning, the fermenter side of the airlock was almost empty of fluid, while the air side was full. This meant the CO2 pressure inside the fermenter had reached a point where CO2 needed to escape through the airlock.
Tonight, the fluid levels dropped back to normal. I took a second refractometer reading on the wort, by taking a little out through the spigot in the fermenter. The wort went into the fermenter at a standard gravity of 1.109. Tonight's sample was 1.085. The calculator on Brewer's Friend says this change corresponds to a 3.15% by alcohol level by volume. Not bad for two days' work by the yeast. This means it's eaten about 20% of the sugars in the wort (which brewers term "20% attenuation"). I'm hoping it will get to 75% or more before it stops completely. I tasted the extra wort I had extracted (about a tablespoon worth) and the flavor was excellent, as was the aroma. I'm hopeful that this cloning experiment will turn out well.
Ideally, by this Saturday it will reach the 75-80% attenuation mark. Then I'll transfer it to a secondary fermenter and harvest the yeast for a future batch. In a few more weeks it ought to be ready to bottle. (Unfortunately, it'll be 2-3 months before those bottles are ready to drink, given the need for a beer of this style to bottle condition and age.)
By the way, if you like Belgian Strong Dark Ales like Gulden Draak, you owe it to yourself to take a trip to The Daily Growler in Upper Arlington. When I last checked, they had Fat Head's "Pimp My Sleigh" Christmas Ale, an excellent Belgian style dark ale. It's been almost two years since I had it, and it still holds a fond place in my memory!
And now to Part 6 - Fermentation Continues...