How to save an infection

[Charmin1073]

Brewed a Pilsner and now I'm pretty sure it is infected. Hydrometer samples tasted fine. Now after conditioning and carbonating it has that buttery taste that can be the result of Pediococcus and has a bit of a sour finish to it. Has anyone ever transferred back to the fermenter and made a sour like this. Was thinking of getting some Brett and see what happens.

regards

 

[GoeHaarden]

Not necessarily an infection...

Buttery taste is usually diacetyl and a sour/green apple taste can be acetaldehyde. Both of which are usually consumed by the yeast itself, it just takes time and maybe a temp increase.

What was you fermentation process/schedule? What is your FG and is it stable?

A pic might help as well.

 

[Charmin1073]

Fermented at 52 for 2 weeks. Raised temp to 60 for 5 days. Final gravity at 1.010. Hydrometer tasted fine. Brite tank for 2 weeks then kegged. Tapped a week later. No pics keg is a sanke.

 

[GoeHaarden]

If your FG is stable at 1.010 then I wouldn't think it was infected as any bacteria would chew up the residual sugars...but I could be wrong!?

What yeast did you use?

 

[Charmin1073]

Lallemand Diamond Lager

 

[RPh_Guy]

If your FG is stable at 1.010 then I wouldn't think it was infected as any bacteria would chew up the residual sugars...but I could be wrong!?

Contaminations don't necessarily result in additional gravity drop.

@Charmin1073 if you're pretty sure it's a contamination based on the taste, and you don't like drinking it the way it is, and you don't mind having a fermenter tied up for several months to a year or more,.... Then yes, you can absolutely pitch Brett or a blend with Brett.

There are lots of good options for cultures you could use. It may not result in the most flavorful beer because the primary fermentation contributed so few flavor compounds, but it can probably still be good.

 

[GoeHaarden]

Contaminations don't necessarily result in additional gravity drop.

Gotcha. I'm probably going to regret saying this (knock on a wooden mash paddle), but I don't have any experience with infections and I'd always thought they just chew through everything. I guess there are outliers in everything...

 

[RPh_Guy]

Remember that we don't actually measure attenuation, but rather the fluid density.
If Pedio is in there turning dextrins into lactic acid, it won't significantly change the density.

 

[Dland]

Some infections do chew though everything, but they explode bottles or foam out of kegs, given enough time.

May not be infected at all. 1.010 is getting close to done, usually.

If it begins to taste awful though, it probably infected, chuck and sanitize all your gear.

(or send it to RPh-guy, he apparently likes that sort of thing {; )

Have not used the yeast you are using, but if it had fermented most sugars out and slowed down by the time you did your D rest, yeast may not have had enough vigor to clean up the beer when you raised temp.

Sounds like it has worked out too much to try to get restarted, but it will likely get better with age, cold crashed and lagered cold. Crash and leave at 33-34 F for 3-5 weeks and I bet it will taste a whole lot better. If it is not infected.

 

[brewcat]

My guess is you racked off the yeast too soon. Using a lager yeast, your best practice is to do a diacetyl test. Basically you heat one sample to 140-158 and hold for 15 minutes. Then crash it to room temp. Compare with an unheated sample. The test detects acetolactate (precursor to diacetyl). The control might taste fine but the heated sample may have a buttery smell/taste (which means it needs longer).

My last lager was a maibock that I checked at 3 weeks. Even after a week long d rest the heated sample still had some butter to it. The control sample was fine but the heated sample definitely wasn't. I left it for another week and then both samples tasted the same. It was then fine to keg.

Aging longer may help if there is enough yeast to cleanup.

 

[Vale71]

My guess is you racked off the yeast too soon.

There's this quaint notion going around that the millions of cells per milliliter that an unfiltered beer still has floating around in it serve no purpose whatsoever whereas yeast that is laying at the bottom of the vessel and has no contact at all with the beer plays a fundamental role in beer maturation and fermentation by-products cleanup. This is as wrong as you can get. Yeast that has dropped can only contribute autolysis flavors to the beer and the sooner it is removed the better it is.

 

[brewcat]

There's this quaint notion going around that the millions of cells per milliliter that an unfiltered beer still has floating around in it serve no purpose whatsoever whereas yeast that is laying at the bottom of the vessel and has no contact at all with the beer plays a fundamental role in beer maturation and fermentation by-products cleanup. This is as wrong as you can get. Yeast that has dropped can only contribute autolysis flavors to the beer and the sooner it is removed the better it is.

My point being, butter taste can be diacetyl from acetolactate. The only way to clean it up is contact with yeast. If you rack you may not be left with enough yeast. Sometimes yeast does drop too soon and needs roused back into suspension (temp rise, light spin of fermenter).

 

[RPh_Guy]

There's this quaint notion going around that the millions of cells per milliliter that an unfiltered beer still has floating around in it serve no purpose whatsoever whereas yeast that is laying at the bottom of the vessel and has no contact at all with the beer plays a fundamental role in beer maturation and fermentation by-products cleanup. This is as wrong as you can get. Yeast that has dropped can only contribute autolysis flavors to the beer and the sooner it is removed the better it is.

Some yeast strains are definitely prone to early flocculation, stalling fermentation. If fermentation can stall, we can extrapolate that cleanup can also stall.

It's been shown over and over that yeast don't cause autolysis flavors in any reasonable timeframe (weeks-months) on the homebrew scale. There's a lot less pressure than in commercial fermentations vessels.

Have a beer Mr. Quaint-Notion Wrong-As-You-Can-Get. Even if people are wrong they don't need to be derided.
Cheers

 

[Vale71]

My point being, butter taste can be diacetyl from acetolactate. The only way to clean it up is contact with yeast. If you rack you may not be left with enough yeast. Sometimes yeast does drop too soon and needs roused back into suspension (temp rise, light spin of fermenter).

Couldn't agree more on the diacetyl issue. However leaving the beer on decanted yeast is in no way going to resolve it and raising the temperature is definitely not going to re-suspend yeast. You'd need to get to boiling temperatures to start any significant convection and that would put a stop to yeast activity once and for all. If the diacetyl is going to be cleaned up it's going to be by the yeast that is still in suspension which will still all be there no matter how many times you rack the beer to a clean vessel.

 

[seatazzz]

I'm going to dissent on the above. I think it needs more lagering time in the keg, with no disturbance. I personally would suggest bringing the keg into the house (or someplace around 68-70°) and leaving it for a week; pulling the PRV on the keg every day to let it offgas. Then chill it, and try it again. From your comments above, you've got diacetyl with a touch of aceteldehyde; both of which will decrease with some time as long as your sanitation was on point.

 

[Vale71]

I'm going to dissent on the above.

Meaning what exactly?

 

[seatazzz]

Meaning what exactly?

Disagree slightly.