Racking onto yeast cake....didn't work?

[ddahcmai]

Hey, so I have a batch of porter that is well and stuck at 1.030 from an original gravity of 1.065. Two days ago I racked it onto a yeast cake from an ale that I bottled that day, and I have seen absolutely zero new fermentation. People seem to be touting this as a foolproof method for restarting a stuck ferment, but maybe I'm just extra foolish. For now I'm just giving it time and letting it sit, but most of you seem to be reporting that fermentation usually kicks off in just a few hours if you do this.

It's great if I should just wait, which I am, but let's assume that for whatever reason it really isn't working, and I need to do something else.

What can I do?

 

[marc06]

My first thoughts are: what yeast and what was the original beer? What was the temperature of the second beer when you pitched it on the yeast cake?

 

[ddahcmai]

Alright, the original beer was a cream ale with Wyeast German Ale. The porter had dry yeast, Danstar Windsor Ale. The temperature of both the porter and the cake was 69 degrees fahrenheit at racking.

 

[Got Trub?]

If a cake of presumably healthy yeast are not doing anything it is because there are no fermentable sugars left. Your high gravity can be from a) poor attenuation by your yeast due to underpitching, unhealthy yeast etc in which case a new pitch can help or b) your wort had a high percentage of unfermentable, complex sugars that no ale yeast can metabolize so adding more yeast won't fix the problem.

is the recipe all grain or extract?

GT

 

[ddahcmai]

This is an extract batch.
I know I likely underpitched this batch due to being relatively new to this and making a starter from dry yeast (oops), I had assumed that racking onto the cake would rectify that situation.

Would making up a proper starter and pitching that be any different than racking onto the cake due to the starter having a high concentration of oxygen?

 

[Dunerunner]

Roust the yeast. Not sure what FV your in, if conical bubble CO2 from the bottom. If it is a bucket, you can remove the lid and gently stir (maintain sterilization). If a carboy, you might be able to get something in it to stir the yeast up, again follow sterile practices at all times.

 

[ddahcmai]

Carboy. I'll try mixing it up somehow and see if that works.
Thanks for all the help guys.

 

[Dunerunner]

Be cautious not to aerate the wert!

 

[Dunerunner]

Be cautious not to aerate the wert!

Purge with CO2 at a very low flow rate, should get most of the air out of the head space.

 

[CA-LT1]

How long did you let the Windsor work? That's a low attenuating strain, and takes 3-4 weeks anyway.

 

[Got Trub?]

How long did you let the Windsor work? That's a low attenuating strain, and takes 3-4 weeks anyway.

Good point but the healthy yeast cake should have finished it off if it was just poor attenuation by the original strain of yeast. Oh I just realized it has only been 2 days. Give it 1-2 weeks and then recheck the SG. You won't necessarily see any vigorous signs of fermentation - I just watched a Belgian Blonde go from 1.017 -> 1.012, it took a week with bubbles from the lock every 90-120". Very boring. Those that report it soon after repitching are likely seeing pre-existing CO2 released from the beer because of the addition - not from new fermentation. Also what brand of extract are you using? They all attenuate to varying degrees.

GT

 

[ddahcmai]

I'm using Munton's DME, this batch had been stuck at 1.030 for over a week before I decided to do this. Rousing the yeast might have worked, we'll see in about two weeks, right now there are very minimal visible signs of fermentation, almost no little bubbles rising to the surface inside the carboy and I'm getting 1 bubble out of the airlock maybe every 5 minutes. For now it's just the waiting game.

 

[Got Trub?]

I'm using Munton's DME, this batch had been stuck at 1.030 for over a week before I decided to do this. Rousing the yeast might have worked, we'll see in about two weeks, right now there are very minimal visible signs of fermentation, almost no little bubbles rising to the surface inside the carboy and I'm getting 1 bubble out of the airlock maybe every 5 minutes. For now it's just the waiting game.

One of the hardest brewing skills to master...

GT

 

[CA-LT1]

You know, I did 2 batches with windsor; a black ale, and a stout. Brewed them a few days apart. One of them I secondaried (last time I did that, I've learned better), the other I didn't. I remember the both seemed to be done in a week, but had really high FG. The ale in the glass carboy, I could see some bubbles coming up, but the airlock wouldn't blip, but I only would watch for a few minutes (yeah, pretty sorry, but I was board) After a month, they got down to about 1.018 or so.

 

[bguzz]

man, you picked the wrong yeastcake to pitch on...windsor is hard to get moderate attenuation when all the stars are aligned on a regular ale.

I've had success pitching rehydrated US05 with a little sugar in it to get the yeasties moving (within 20 minutes of rehydrating)...pitch while it is foaming and they will eat whatever is left that can be ate.

 

[ddahcmai]

Unfortunately that was the only yeast cake I had to pitch on, but it worked just fine for the ale that it produced. Wouldn't pitching rehydrated USO5 at this point not do much because there is no oxygen in the wort for them to reproduce with? I feel like I might end up with frankenbeer using so many types of yeast!

 

[bguzz]

I think the goal is to get the active yeast (rehydrated = ready to go) into the beer, you aren't looking for growth now, just to finish it off. The reason you need to rehydrate is the alcohol present now is toxic to weak yeast...if you just sprinkled the dry yeast, it would likely not do anything at all.