Started at 65°F and increased 1°F daily, controlling the wort temperature (no free rise).
I added a fair bit of yeast nutrient too.
I used a vitality starter with wort from the batch.
It definitely didn't have any off-flavors from fermentation, even at 9% ABV.
I made the yeast too comfortable?
I never know how to approach talking about these yeasts. There is certainly a generally accepted temperature control dogma around the big 3 (1214/500, 3787/530, and 1762/540) in particular but also "Belgian" yeast in general.
As far as the Chimay yeast is concerned, it never hurts to look at what Chimay actually does, even if it means we can't actually replicate that ay the homebrew level.
For one, Chimay produces a lab grown pitch for every batch and does not re-pitch their yeast. This is actually similar to what most people are doing at the homebrew level anyway. More of a side note I guess.
As far as fermentation is concerned, they pitch at 68 F and it reaches the low 80s by 4 days in. These temperatures are no doubt aided by the yeast itself and the large CCV fermenters they use. Obviously this could turn into an untenable scenario for the homebrewer given the fermenter geometries we are saddled with, temperatures, etc.
For a long time I have been researching the many variables at our disposal for fermentation with Trappist yeasts. The most important are as follows:
1.) Wort Composition (Amount of Starting Extract);
2.) Attenuation;
3.) Pitching Rate;
4.) Fermenter Geometry;
5.) Fermentation Temperature;
6.) Aeration
What are the variables we can control?
We know that
Fermenter Geometry is out of our control and in order for the size of a fermenter to affect, in a significant sense, the ester and higher alcohol synthesis it has to be significantly larger than anything the typical homebrewer will be using. So that's out.
Wort Composition is an interesting one because we can control it, but it's tied in with
Attenuation, especially in these types of beers, i.e. If we have a higher Original Extract (OE or OG), we may end up with lower attenuation, but if we drop the OE, we may get higher attenuation. If we keep our eyes on Chimay for the moment, we can see that their beers have lower OE values than would be expected by most and higher attenuation.
We know that beers with higher OE exhibit higher levels of esters so we can utilize Wort Composition as a tool so long as we keep Attenuation in mind.
Pitching Rate is another variable we can control, especially if you do cell counts and have a good feeling for how much we are actually pitching. Even if you don't, the rate of pitching can be used to control how much growth we have in the initial phases of fermentation. What we mostly want to do, especially in these beers is promote a healthy amount of ester synthesis while limiting some (hot, solventy type flavors), but not all higher alcohols.
We can buck the conventional wisdom here by pitching at a higher rate than "normal" for ales.
Aeration is a huge one. It is typical for most people to aerate the bejesus out of the wort because they have the fear of God in them that if they don't they won't have a healthy fermentation. As it turns out, there is a direct correlation between aeration and yeast growth, and yeast growth promotes higher alcohol synthesis. Not always a good thing when elevated temperatures are involved (more on that below).
Lower Aeration and higher Pitching Rate can help to limit yeast growth and the promotion of undesirable higher alcohols.
Lastly, we have
Fermentation Temperature. Frankly, yeast don't want to have the temperature they operate at limited. From the standpoint of a yeast cell, elevated temperature lets them rock and roll. Brewers, however, don't always have the best luck with elevated fermentation temperatures (especially with WLP500/WY1214), especially when conventional wisdom has them starting with high OE, aerating the hell out of the wort, using too much yeast nutrient, and underpitching for these types of beers.
If we tweak some variables from above as discussed, we can modify temperature control to allow for healthy free rise with no adverse affects.
Sorry for blabbing on so much.
What do I recommend?
I have been using the following with 3787 (My house yeast) with great results. YMMV but I think it captures some tweaks to the "standard" practice that may get you what you are after:
1.) Shoot for lower Original Extract values (OE/OG) and let Attenuation drive the desired alcohol content.
2.) Pitch at a rate that may seem a little higher than what you are accustomed to, i.e. > 1.00 M/ml/P (I target 1.25)
3.) Reduce Aeration (if using Pure O2) or (like me) use a filtered air setup.
4.) Be careful with yeast nutrient. Technically wort has all the nutrients required and additional nutrient could have levels of Mg and Zn higher than required/what is healthy for the yeast.
5.) Do not control temperature at all. Pitch cool (62-64F) and let the beer free rise to completion. Certainly track temperature (I use a cheap digital thermostat with block letter readout in a thermowell) and record for posterity and revision. My basement is essentially a constant 64F ambient all year and I submerge the fermenter in a water batch and if I pitch at 64F, the temperature generally stays below 66 for the first 24-36 hours and then begins to rise naturally, with temperatures rarely exceeding 68F until 48 hours in. It then rises into the 70s and I don't attemporate at all.
I hope this helps!
