Isolating the bugs from Trois Dames Oud Bruin

Eureka, it has been a while since the last post about isolating some wild bugs from a commercial beer. Luckily, there are still some beers in my cellar with bugs I would like to isolate (Orval, Lost Abbey, BFM, Cantillon, Jolly Pumpkin…). The beer I am talking about today is from a Swiss brewery called Les Trois Dames (The three women). This brewery produces an Oud Bruin (Flanders Brown) made with apricot wine. The beer comes with an ABV of 7.2%. Maybe some of my tasting notes first.

Aroma: Sour and funky smell. Pretty awesome! Could detect some cherry notes. In my opinion one of the best smelling beers in Switzerland…

Appearance: Red-brown color, clear appearance, 1 finger tan head with some carbonation. Nothing special here.

Flavor: Now begins the fun part… Unfortunately, the complexity of this beer is very limited. I could detect some sour cherry notes. The sourness is just right. Not too overpowering. However, nothing else. Not even a hint of apricots…

Mouthfeel: Light body, average carbonation level, pretty dry and sour finish.

Overall Impression: There is the right amount sourness in this beer and the aroma of this beer promises a lot. Unfortunately, the flavors speak another language. The beer has a very limited complexity in my opinion. Maybe the beer was too young? Only a second tasting could tell. To summarize, this is a pretty nice beer and because this is a beer made from a Swiss brewery, it is a winner for me for sure. I would give this beer a rating of 85 out of 100. I am a bit disappointed about the lacking apricot notes. I should get myself a bottle of apricot wine one day and compare the apricot flavors there. Maybe the apricot flavors are already very subtle in the apricot wine?

Anyway, this post is about the bugs in the beer. What I did is already a standardized technique for me to isolate some bugs from such a beer. I made myself a small DME (dry malt extract) starter and dumped the dregs of the beer in there and left it for some days. Approximately a month later, I plated some of the starter liquid on some Sabouraud agar plates and waited… Eleven days later, there were some colonies visible on the agar plate (Fig 2).

Fig 2: Sabouraud agar with colonies of Les Trois Dames Oud Bruin bugs after eleven days

The colonies morphology: White, not glossy, wavy margin, convex elevation, circular and the plate had a hint of an acetic acid smell. The acetic acid smell already made me wonder what I got myself here. I then picked a single colony and had a look at it with my microscope.

Fig 3: Les Trois Dames Oud Bruin bugs

Fig 4: Les Trois Dames Oud Bruin bugs

First of all, due to the size of the cells, I assume that all the cells visible in the following pictures are yeasts. I could observe some oval formed cells and some with the mysterious vacuole (Fig 3). And yet again, some cells which adhere to others (Fig 3). For me some of the cells in Fig 3 look like normal brewers yeast (Saccharomyces cerevisiae) and others don’t. Then again, I could observe some elongated cells (Fig 4). I already have an idea about these cells but will have to do further research first. Lets move on to the picture at a higher resolution.

Fig 5: Les Trois Dames Oud Bruin bugs

There are these dark spots again which I could observe in Brettanomyces bruxellensis before (Fig 5). My conclusion from the observations. I assume that I got myself some Brettanomyces bruxellensis and maybe some other Brettanomyces species. Some Saccharomyces cerevisiae could be in there as well. I guess this is all I can tell you about the bugs right now without doing any sophisticated lab tests. Nevertheless, I once again could show that it is possible to harvest some wild yeasts from a bottle. My next steps concerning wild yeasts will be further investigations about the elongated cells as it can be seen in Fig 4. There is a hypothesis in my head what these cells might be and I already found some promising evidence for my hypothesis. Another running project is to isolate the bugs from a Cantillon Kriek. Will post about the results for sure. By the way, the starter I made with the dregs from the Les Trois Dames bugs had no pellicle. Stay tuned for further yeast ranching experiments. Cheers!

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