I am happy to report that isolating the yeasts from The Mad Fermentationist’s DCambic was a success. I have written about it previously and had some issues at first. A lot of stuff going on in life then kept me from the project for a few months but eventually I got the time to get it going again. I have been posting off and on about it on Twitter, but it’s time I document it here.
The key to success the second time was growing a liquid culture first from a sample Mike gave me, rather than plating it straight from the sample. After a few step-up culture iterations I was able to isolate four different yeasts from the beer, instead of just the one I got the first plating attempt. Two were useless for brewing: one is possibly Rhodotorula and the other is another yeast that does not ferment. The others were almost certainly Brettanomyces.
I can tell them apart on a plate because one (DCY02) grows white colonies and the other (03) tan colonies. Liquid cultures are also markedly different: DCY02 forms a pellicle very quickly, smells very funky and drops out fairly quickly, whereas DCY03 takes much longer to form a thinner pellicle, smells very fruity and drops out a lot slower. Taste profiles from the starter are along the same lines as the smell.
I made two simple extract beers in April (1.040 of pilsner DME) and the picture above is of fermentation about two weeks in. They were slow to start but that may be due to low pitching rates. In any case, I have not yet bottled these as they seemed to reactivate after I moved in late May. Perhaps just shaking them a bit roused enough yeast into suspension to do something, and I want to make sure they’re done before I bottle. (I will update this once they are done.)
DCY02: The “white” isolate, based on colony appearance. This has a funkier Brett character with less of the fruity qualities. It produces a pellicle very quickly, and during fermentation produces a thick foam cap that looks more like Sherry flor than ale yeast kräusen. It dropped out of suspension faster than DCY03.
DCY03: The “tan” isolate. This is significantly less funky, and a lot fruitier. It doesn’t produce much foaming during fermentation, and in fact may appear to be doing nothing at all. If shaken, though, there will be a lot of CO2 released. It did not produce a pellicle until several months after pitching and left the wort cloudy for about a month.
I hope to have more details soon, both from my beers but also from those of a few brewers I sent samples to. This was also the first time I’ve distributed anything so I kept it limited to four people. However, in the future I will release larger amounts to whomever wants it for a small fee to cover shipping and materials. Future announcements will be made on the blog and on Twitter.