Propagating Rochefort yeast

[chthon]

Last fall I propagated Rochefort yeast from a bottle of Rochefort 8. I actually did this also in 2017 with Westmalle yeast and in 2018 with St.-Bernardus yeast, but I documented it better with the Rochefort yeast.

The reason I show it here is don't have a stirplate (might come, I discovered I still have some computer ventilators that I could reuse for that, while cleaning up the attic, because of all the time that I got being in lockdown).

In the first phase, I collected the bottom of the bottle into a test tube and added a bit of wort (1.020). This picture is taken a couple of days later.

I added again a bit of glucose at this point and let it ferment out further. This is the result 10 days later. The depot in the second photo was clumped together and needed a fair shaking to decompose it.

 

[chthon]

In the third step, I used the result from the test tube to grow the yeast further and then build a starter for a small bit of beer.

This is the third step to increase my yeast.

And this is the fourth step, where the goal was to also use this to ferment a small amount of beer (yes, it is a bit of work, but why not put materials to good use). So, I brewed 1.5l of light beer from LME.

(Note: I should actually thank @Count Drunkula here, because of a remark somewhere about brewing light beer to propagate yeast)

 

[chthon]

In the next step, I brewed a still larger amount of light beer to increase my yeast.

This is the color and gravity at the start of fermentation:

A picture of the fermentation:

After fermentation:

This yeast goes real deep, and this was also a wort that was mashed rather low.

 

[chthon]

In the last step I brewed my home recipe, to get a big amount of yeast.
This is the beer in a secondary vessel:

And this is the primary fermentation vessel with a picture of the trub and yeast at the bottom:

 

[chthon]

And then I washed my yeast, because with the previous times I noticed that there is a whole lot of trub and a bit of yeast.

Trub collected from the fermentation vessel:

And here it is put in a jar to be able to collect the first and second layer of liquid:

I used this then to wash the yeast in different steps, to get a maximal yield.

 

[chthon]

Finally, I put this again in the fridge, to wait until the yeast was completely precipitated and the supernatant was clear.

After this, I drained the supernatant and collected the yeast in a small jar. From this, I then always build a small starter, using appr. 3 to 6 ml of yeast.

 

[chthon]

Results from using the yeast

• The Rochefort yeast has a rather low flocculation, although it is better than a weizen yeast
• Based upon all recipes I have brewed, the apparent attenuation is 90%
• This yeast also seems to work well in the fridge. When putting the third growth in the fridge to cold crash, it kept fermenting slowly.
• Big and long lasting kraüsen

Tasting notes
What I noticed with the second beer I brewed, and which contained 10% wheat flour, is that the yeast would accentuate this, so that this beer tasted a bit like a witbier.
In other brews, the yeast is always subtly present, but no banana or clove notes.

 

[strange-steve]

Good work there @chthon thumb
How does the flavour compare to the yeast profile in Rochefort beers? WLP540 just isn't quite the same in my experience, which is a shame because I really love Rochefort. I actually have a bottle of R8 at home so I might follow in your footsteps thumb

 

[chthon]

Good work there @chthon thumb
How does the flavour compare to the yeast profile in Rochefort beers? WLP540 just isn't quite the same in my experience, which is a shame because I really love Rochefort. I actually have a bottle of R8 at home so I might follow in your footsteps thumb

Since I currently have only brewed light coloured beers with them, difficult to say.

I just looked it up (but I don't know the source or date of the article) and found one which says that after primary fermentation, Rochefort is filtered through a diatomaceous earth filter. This will probably get rid of a whole lot of yeast, but not all. I have only a bit of time, patience and temperature to play with.

From what I remember of tasting the beers, it seems that the yeast profile I now get is not as strong in the Rochefort beers themselves. That is, I probably do get their esters + yeast, while in the Rochefort you will mostly get the esters.

An additional note: I bottle with CBC-1, which is a killer yeast, and it helps clearing my Rochefort based yeast, but a light yeast haze still remains (does not disappear at higher temperature). Westmalle and St.-Bernardus clear without help.

 

[Cestrian]

Great job @chthon thumb
This takes me back. I used to love harvesting yeast and trying to clone trappiste beers. I used to work in Belgium so would always bring a good selection back with me. Rochefort was probably my favourite trappiste beer, but I found westmalle much easier to work with. One thing I found with these yeasts is you have to raise the fermentation temperature quite a lot to get the funky yeast flavours. There are so many variables though, they are difficult to clone. Interesting though if you’ve got the time. “Brew like a monk” by Stan Hieronymous is a good resource.

 

[chthon]

@Cestrian : I own the book already four years, I think.

That about the temperatures I had a suspicion about. With those yeasts I don't cool further than 20°C. The fermenters get a jacket of towels and are kept in a room where the temperature never goes below 20°C, and I let them do their work.