Wood cubes and glass soleras

[TAK]

How important is wood to a solera program being held in glass carboys?

I've heard of people boiling the crap out of some wood chunks to strip away the toast and wood flavors, because those aren't the goal. Rather, the wood is a place for the bugs to live, and some carbs for Brett to eat.

I have one carboy started now, and I have two more that I'll be filling soon. The first one doesn't have room for wood chunks now, not without removing some beer. But I could always add them at my first pull and refill.

How important is wood to keeping a healthy resident population of bugs?

I'm not exactly sure what my ultimate method of pulling and refilling will be, but it seems that I'll always have a small and revolving cake of bugs sitting in there without wood. But I'm wondering if I should drop some chunks into my next two carboys anyway.

 

[gregkeller]

I don't think wood is so important to a solera. I really think that if anything having it in glass/stainless would allow you to keep the solera going longer than normal because you are getting very little oxygen into the fermenter and that should limit the acetic acid production (vinegar). It would also keep you from giving up an "angel's share" due to evaporation. I was thinking it would be awesome to use a 15 gallon keg, have ball lock fittings welded on and do a solera in there with 13 gallons of lambic, pulling 4-5 gallons every year and replacing it with fresh wort. The fittings would allow me to push beer out of it without having to lift up the keg with 90-100 lbs of beer in it high enough to rack it.

 

[Curtis2010]

Interesting. All commercial soleras I know of are based on wooden kegs (rum, balsamic vinegar...). Is this non-wood solera something you are just trying out or are there existing examples of it in other commercial or HB applications?

 

[gregkeller]

I don't know of any stainless/glass Soleras, but the two examples you gave it seems like having the liquid in wood is important. For balsamic acetobacter is what's producing the acetic acid and that is an aerobic bacteria, the small amounts of oxygen that make it into the barrel are what gives you that flavor. With rum, especially the aged ones you are getting a lot of flavor from the barrel itself I would think.

With sour beer it is rare that you want real wood flavor in it. Now brett can eat the wood and produce vanillins and other compounds that you can't get without oak but I would think a few oaked cubes that have been boiled a few times would provide the same affect.

I haven't actually done the solera yet but it's on my list of things to do. When I do, I'm almost certain it will be in a sankey keg.

 

[Curtis2010]

On my list too, that's why this caught my attention.

 

[TAK]

Interesting. All commercial soleras I know of are based on wooden kegs (rum, balsamic vinegar...). Is this non-wood solera something you are just trying out or are there existing examples of it in other commercial or HB applications?

I don't have any reference examples in my back pocket, but sure I'm not the first. I'm pretty sure I got the idea mulling through HBT threads.

As gregkeller said, with sour ale, lacking even micro-oxygenation is okay.


This is one reason why I'm considering adding boiled, "deflavored" oak...

brett can eat the wood and produce vanillins and other compounds that you can't get without oak but I would think a few oaked cubes that have been boiled a few times would provide the same affect.

... but the other reason, which is more of my original question, is would the wood cubes provide an important roost for the resident bugs to live generation after generation?

 

[ChefRex]

Nothing to add at the moment but interested, have a couple sours going and I'd like to follow along.

 

[kingwood-kid]

I don't think the microbes need wood as a place to live in a solera. Given that you're never completely draining the carboy, there will always be some yeast and bacteria present. Traditional sour brewers don't solera; they will drain any of the foeders completely as they blend. Since they theoretically never pitch new yeast, they have to rely on what is already there. I could see where you would get some flavor from the wood, although I imagine it would be diminished with every iteration of the solera.

As far as oxygen goes, the small size of a homebrew solera greatly skews the surface area to volume ratio as compared to a giant foeder. More oxygen gets into a 5-15 gallon carboy through the stopper than gets into a foeder. Unless you like acetic acid, oxygen at this stage is to be minimized.