Tag Archives: lambic

DCY02 & DCY03: DCambic Isolates

DCY02 and 03 Fermentation in Progress

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.)

Strain Descriptions

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.

Distribution

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.

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DCambic Plate Growth

It’s now been about a week since I plated the DCambic sample. A few days ago I began to see growth of what appear to be yeast colonies growing on the malt extract plate. They are round with small peaks in the middle, and appear to be a little glossy. It’s hard to tell right now because I am not opening the plates just yet to avoid contamination. I want to leave these out for at least three weeks to allow any slow-growing organisms to appear.

There is also some yeast growth in the liquid sample. I began to see a layer of sediment a few days ago. No pellicle or visible signs of fermentation, but the pH dropped to the mid 4 range (using strips to check) and there was a somewhat Bretty aroma. There is a little funk but the dominant smell is sort of fruity, not unlike canned peaches. I am stepping that up to 250mL as we speak.

Once I’m done with incubating I will streak out the individual organisms and grow them in liquid. It’ll be interesting to see if I get the same characteristics as in the current liquid sample.

DCambic Plating

Last week Mike the Mad Fermentationist gave me a sample of his spontaneously-fermented DCambic. I had just made some brilliant green agar plates, from BKyeast’s excellent post on media. This media is antibiotic, killing most types of bacteria while allowing yeast to grow. My first thought was to plate some sort of lambic, hopefully being able to isolate the yeasts present. I figured what better lambic than a local one, and Mike was kindly willing to give me a sample.

For this plating I did my first serial dilution. I had previously only done streaking using a needle, whereas this involves placing a small amount of dilute liquid and spreading it around the whole plate. I diluted it 1:1000. I picked that factor somewhat randomly. I was planning on doing at least 10^6 as I had read somewhere, but since I was starting with a clear beer sample and not the dregs, I figured it wouldn’t need anywhere as much dilution. I had previously prepared vials with 9mL of distilled water, so I just had to pick three of these vials. I added a small amount to a brilliant green agar plate and a simple malt extract agar plate, and spread it around with a cell spreader (“hockey stick”). At the same time I also added about 5mL to 50mL of sterile wort to see what would grow in liquid media.

I did this on Saturday, and as of today, Tuesday, there is nothing growing yet. The plates are clean, and the liquid sample is still clear. I am afraid I made a dumb move and tried to do this after the sample had settled in the fridge, without shaking it up. If nothing grows soon I will try plating again. I already added another 5mL of the shaken-up sample to the liquid. Hopefully there will be some growth there soon. In any case, I will definitely post updates as this goes on. Who knows, maybe I’ll be able to isolate an interesting Brett from it. I would also love to isolate the saccharomyces that did most of the fermenting, though there might not be any more in suspension at this point.