Can mannose continue to sour a beer? (Pedio, FG <1.000)

[stpug]

Here's the scenario:
A 10 IBU saison pitched with sacc and dregs containing brett and pedio (lacto too if it matters). Initial fermentation resulted in 1.007 FG and sample lacked any sour qualities (to be expected). Fast-forward 3 months, fermentation is <1.000 FG (0.999 currently) and sour qualities are only about a 2/10, and I'm aiming for about 6/10.

Here's the question:
Does anyone have any information (anecdotal or not) on pedio's abilities to continue to sour a beer whose apparent attenuation is sub-1.000 or am I waiting for nothing? AA is only "apparent" attenuation and I recognize that there are still various carbon sources remaining in the beer. I'm interested in knowing if anyone has info that pedio can continue to sour a beer like this (even if it's slowly, I'm okay with that)?

Commentary:
I know there are options to increase the starch/sugar content of the beer at this point to allow the bacteria and yeast to continue to work, but ultimately I'd prefer to let it work slowly if there's a good chance of it doing so. One potential caveat is that giving a typical carbon source (e.g. maltodextrin) to a beer containing brett may prove futile since the brett will likely act on the source before the pedio can do much. One carbon source that is utilized by pedio but not brett (based on what I've gathered) is mannose which can be picked up for a pretty penny on amazon.

I know that there is likely no definitive answer to this but anyone who has experienced the similar situation with any input is appreciated, or has any information on pedio's useful carbon sources more than I have already drudged up would be helpful.

 

[ColoHox]

There is some evidence that a mixed culture containing Brett and Pedio in particular can result in "superattenuation." However, in the paper, a superattenuated lambic is 1 Plato.

Paper link

BYO article mentioning the synergy

I wouldn't expect much more to happen to a sub 1.000 SG beer.

 

[stpug]

Thank you for your reply. I appreciate you taking the time to find and post that information.

I was afraid of confirmation that not much more is going to happen without some sort of intervention given my current gravity level. I suspect that my course of action will be to give it 1-2 months to see if something more develops inside the (room temp) keg, and if I find that it's not progressing/souring then I'll try adding a food source for the remaining bugs to feed on (probably a mix of maltodextrin and mannose - not totally sure just yet).

Thanks again!

 

[foltster]

Another option would be to make another much more tart/sour beer and blend the 2.

Or you could add some lactic acid directly, too much can be bad but you can sort of cheat your way to some more tartness.

Another option is to wait another 2-3 months and see if anything develops. This is probably what I would do.

Might be worth a quick calibration check on your hydrometer as well just to be sure.

 

[stpug]

Just to bring this thread up-to-date:

Two and a half weeks after my OP, I took another sample and the results were the same. Barely any tart quality to the beer (let alone anything remotely resembling "sour"). The beer could be considered balanced in terms of malt sweetness and contrasting "other" character (tartness in this case). I decided to add 0.75oz mannose that was boiled in 4 oz water to the keg and let it sit at cool room temps (~65F).

Fast-forward 4 weeks: tartness level has gone up a decent amount and has passed the "balanced" stage to where I actually notice a bit of tartness to the beer. Still no where near where I hoped it would end up. The mannose seems to be working so I add another 0.75oz in the same fashion as before.

Fast-forward 5 weeks: I pull a sample and to my surprise the beer is definitively SOUR. I'd call it a 6 or 7 out of 10. I have my wife sample and her face cringes and she shakes her head - PERFECT! The flavor is top-notch with some used white wine oak cubes I added 4 months earlier. On tap it goes

While it's only a single data point, I feel as though the mannose sugars provided a carbon sugar source that only the pediococcus could work on which allowed the souring of the beer to take place in relatively short time without feeding the other microorganisms in the beer. I have another bottle of mannose for a future batch of pedio-sour beer in case it's needed.

In regards to the mannose source used: I picked up some D-mannose capsules that I would open and boil in some water. The capsules also contain some silicate filler which proved to be unsightly and remained undissolved, and had to be scraped from the surface during the boil (which was only partially effective). Next time I will opt for a jar of pure powder to avoid the silicate. Also, mannose is fairly expensive so if I can avoid needing to use it in future batches then I will obviously opt for that, however it did seem to allow me to finish souring a batch in a relatively short period that had basically stalled - so, as a tool, I think it's worth knowing about. I'm super-stoked that this batch finished as sour as it did because it basically sat at neutral for four months at <1.000 gravity. Besides, the mannose powder is no where near as expensive as buying 5 gallons of what I produced (that would have emptied my savings account ).

 

[ColoHox]

Thanks for the update. Your findings are really interesting.

 

[berebrando]

Agreed - interesting!