I’m fermenting a clean Saison and will put a few mL of brettaonmyces starter into each bottle before capping (same thing that RR and SN did with Brux).
OG 1.055
Mostly pilsner and a little wheat and munich
34 IBU Rager, Magnum at 60 and some Hallertau at 10 min.
Primary Wyeast 3724
Secondary Wyeast 3711
I’m using two different yeasts because 3724 is very finicky and 3711 will tear through anything and get down to 1.002 in 10 days. Being that this will be a very dry beer to begin with and that I will be adding brettanomyces I want to avoid bottle bombs. I’m going to carbonate to around 3.2 volumes of CO2. Being that the FG will be around 1.002 will there be anything else for the brett to eat besides the priming sugar? And if the brett will possibly eat more sugars than just the priming sugar should I shoot for a lower volume of CO2. Let’s say I want 3.2 but to shoot for 2.7 or 2.8 because the brett may eat other sugars?
I would tend to think that you should shoot lower. My Berliner Weisse finished at 1.000 after five months. I kegged, so I didn’t have to worry about the bottling issue, but if I had bottled earlier, there would have been priming issues as you are suggesting.
The Brett will eat those last couple gravity points, so take that into account. With only those couple gravity points and the priming sugar to work with, you’ll have a pretty subtle Brett character.
Brett will also work on the esters, hop compounds and alcohols once it eats the remaining starches and sugars. I do not believe it converts the esters, hop compounds or alcohols to gas but you will get some flavor compounds out of them.
I would go in with the assumption that brett will ferment out the last two points. It might take some time (maybe even months) before the remaining sugar and starches are fully fermented so depending on your expected timeframe for drinking the beer you may not want to fully discount the priming sugar for the remaining two points. Personally I like to keep some of those brett beers around to see how they evolve but I bottle them in sturdier glass than the typical 12oz bottle.
General rule of thumb is that each gravity point adds an extra 0.5 volumes of CO2. Typical priming sugar amounts add about 3 gravity points (which is convenient for me because I always forget to measure my FG until after I mix in my priming sugar )
Its all about the timeframe you’ll drink the beer in.
If you’re going for a little wisp of musty/cherry pie brett flavor, you’ll probably drink it long before the small pitch of brett converts those last 2 gravity points.
If you want to keep a few bottles around (more than 6 months), get just a few sturdy Belgian bottles instead of a whole batch-worth.
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