Topping off

[monkeymath]

Hey guys,

I recently started my first long term sour project (a Flanders Red); primary fermentation with sacch only, then transfer to secondary with brett, pedio and various bottle dregs. The batch size was my standard 20-22l (can't fit much more in my 30l Speidel fermenters with the kraeusen and all) and there's still room for roughly 10 liters, which I would of course like to fill. I see various ways to do this and I cannot really decide which one is best:
(a) add fresh wort,
(b) add fresh wort and a yeast starter,
(c) add fully fermented (young) beer.

(a) and (b) add more trub and require additional headspace for the renewed "primary" fermentation, but potentially give the bugs - which had so far been deprived of simple sugars - more to chew on. With (a), I wonder what adverse effects a sluggish fermentation might have (the beer already has an alcohol content above 6%, so I think an infection is rather unlikely to happen at this stage, but we've all seen the pictures of glorious mold in fermenters...), which is why (b) might seem attractive, although it does again reduce the amount of food left for the bugs.

What are your thoughts? What is your preferred method?

Thanks in advance,
~ Daniel

 

[RPh_Guy]

Adding wort + yeast or actively fermenting beer will reduce the risk of THP.

Adding clear wort or fermented (and clear) beer will reduce additional trub.

There really should not be much worry about kraüsen, assuming the amount needed for top-up is relatively small—less than 15% of the total volume..

Personally I would add some fermenting beer as it nears the end of active fermentation. THP and oxidation are more concerning than yeast sediment in my opinion.

 

[monkeymath]

Adding wort + yeast or actively fermenting beer will reduce the risk of THP.

Adding clear wort or fermented (and clear) beer will reduce additional trub.

There really should not be much worry about kraüsen, assuming the amount needed for top-up is relatively small—less than 15% of the total volume..

Personally I would add some fermenting beer as it nears the end of active fermentation. THP and oxidation are more concerning than yeast sediment in my opinion.

Thanks for chiming in, I appreciate it!

Avoiding oxygenation (or, rather, enabling the uptake of introduced oxygen through active sacch) and THP seem more urgent, although I don't know the exact impact trub (not just yeast sediment) may have on long-term aging.

As for the volume, I'm actually talking 40-50% of the current amount: I have roughly 20l in a 30l fermenter, so ideally I'd like to add another 8l or so - which will probably induce a sizeable kraeusen, I'm afraid. Not a good place for the Westmalle strain I used in primary, as that one makes a huge kraeusen. Maybe a lager yeast would be best? Not looking for a massive flavour contribution here...

 

[SteveO820]

Another option I've seen people use is clear marbles to take up space if they don't want to add anything to their current fermentation but need less headspace. MoreBeer(dot)com has them but I'm sure you can find them at a crafts store.

 

[RPh_Guy]

I don't know the exact impact trub (not just yeast sediment) may have on long-term aging.

It's sort of an unknown variable. Based on my limited experience, in some long-term sours I get quite a bit of autolysis flavor over time, and in others I get none (even while aging in identical conditions). I suspect this occurrence varies largely by the Saccharomyces strain(s), with other factors playing a role such as temperature, Brettanomyces strains, alcohol level, etc.

It's also worth noting that some people prefer the autolysis (savory) flavor complexity and intentionally try to encourage it. There are others who suggest that autolysis flavors don't occur at all, and while that's clearly untrue, I think it leads weight toward the idea that it won't ruin the beer.

Aging on trub from turbid wort (from break material, not starch) may possibly increase the barnyard funky flavors from Brett.

Personally, I don't like autolysis flavor in general (even with certain yeast strains known to give positive flavor characteristics such as Lallemand D47), so I use methods to achieve the flavor profile I want in a short timeframe. I've found even my more traditional aged sours I enjoy them best within the 5-8 month range, and I attempt to manipulate the hop rate so that it will sour neither too fast nor too slow so that it will be ready in that window. Under my aging conditions (63-73°F), I usually don't detect much autolysis until after around 9 months at the earliest, with the possible exception of D47.
I despise THP; however, some people are taste-blind to it, so YMMV.

As for the volume, I'm actually talking 40-50% of the current amount: I have roughly 20l in a 30l fermenter, so ideally I'd like to add another 8l or so

Sorry I missed that in your first post.
I'm not sure whether using another strain would help in this case. You may just need to top-up more than once.

Hope this helps.

 

[sweetcell]

personally, i would add fully fermented beer (option c), or as RHP suggested beer that is at the end of its fermentation but still (just barely) active). make sure you have some sort of air lock or pressure release gizmo on your fermenter, as the brett will ferment the long chain sugars in the new beer (and, depending on the age, of the original beer too).

i too am sensitive to THP, but i don't think it would be a concern of mine in this case. even if any introduced oxygen results in the stuff, you're going to be aging it for months - plenty of time for brett to clean it up. in my experience, THP always goes away with time - typically 2 months, give or take.

i fully support anyone's efforts to keep their long-aged fermentors topped up

 

[goodolarchie]

I like Sweetcell's Option D, beer that has already had it's krausen fall but is still active, so you don't have to worry about headspace. I'm assuming you are trying to bring the beer up to the neck / past the widest point on the shoulder, to eliminate headspace and surface area? This is generally a smart move for an extended secondary. I wouldn't worry so much about THP, presumably you'll let it age long enough that it would come and go if it did, it's more about leaving some additional sugars for your bugs in the flanders to chew on, and that you still have some active sacch to reduce oxygen-derived off flavors. Acetone / ethyl acetate is the worst and just won't leave.

 

[mashpaddled]

I'm not usually one to worry too much about headspace in a non-barrel vessel but if you have a third of the vessel empty then it's probably the right move to top up. It's too much headspace and a lost opportunity to produce more beer from the same occupied fermentation vessel.

Adding fermented beer will be the easiest route because you'll develop less trub and have to worry less about the need for headspace. The other options would be fine as well but potentially come along with the need to deal with krausen and blow off. I don't think you need to supplement with yeast or LAB either way. What is already in the beer should be more than enough.