Pitch Rate and Temps Advice - Stuck Fermentation

[sarandos25]

All,

Second time this recipe got stuck around 1.020, I'm looking for advice to make sure I am not putting the yeast under too much stress or over-pitching. Below is the recipe, pitching approach and fermentation temp schedule, I'd like any feedback in case something looks off:

Grain Bill
67% Pale
10% Munich
23% Caramel / Specialty

Other Recipe Stats
SG 1.060 Target FG 1.012
Fermentation Temp: 60F
Yeast: US-05 Dry (happy range 59 - 71.6F; full range 53.6-77F). Recommended rehydration water temp: 77-84F

Below is the approach I have followed the last 2 times:

Rehydration:
Rehydrate at 84F, lower in fridge/ ice bath to 68F, pitch at 68F within 90 minutes

Fermentation Temp Schedule
Reduce temp from 68F to 60F during the first 8 hours after pitch
Maintain at 60F for 7-10 days (however, I have had to raise the temp by day 5 the last 2 times to try to get the last 8 Gravity points without any success)

Pitch Rates:
Standard Ales (i.e. lower that 1.060 and fermented at temps higher than 65F) call for 6 Million Cells per ML. Because of the gravity and temp in this recipe, I have been going with 12 Million Cells per ML. Am I over pitching?


I understand the cause for the stuck fermentation may be in the mash; I'm working to ensure that is not the case. However, I want to rule out issues with the fermentation approach, I appreciate any feedback on this part of the process.

Thank you in advance for all advice and feedback.
Thank you!
Chris

 

[yowzers]

With 23% caramel you have quite a bit of unfermentable sugar. Your yeast is fine and you are way overthinking this. US-05 is fine at mid 60’s. Don’t make it too complicated. 23 % caramel malt is like adding molasses to your coffee, it’s going to be sweet. Cut that down to 5%. Your mash is fine. Stop fermenting in the low 60s when high 60s are better.

 

[sarandos25]

I'm providing more granularity on the grain bill to see if that changes your thoughts @yowzers

Grain Bill
67% Pale
14.5% Various Caramel
10.5% Munich
8% Brown / Chocolate

Stop fermenting in the low 60s when high 60s are better.

That's what the recipe calls for (i.e. I am following a recipe)

With 23% caramel you have quite a bit of unfermentable sugar

Are you saying that even though the recipe calculator says I should go from 1.060 to 1.012; not all of those 48 Points are fermentable?

Thanks

 

[Erik the Anglophile]

What is your mash temperature? That is quite a bit off crystal and a bunch of other specialty malts, mashing too high with that grainbill is likely gonna cause under attenuation.

 

[BrewnWKopperKat]

That's what the recipe calls for (i.e. I am following a recipe)

What is the source for that recipe (book, web site)?

eta: I've brewed a couple of batches with 20% crystal and US-05 - and got good results. I've brewed some with US-05 in the 57-60F range as well (but not both in the same recipe). I may have more observations after knowing more about the source of the recipe.

 

[BrewnWKopperKat]

I understand the cause for the stuck fermentation may be in the mash; I'm working to ensure that is not the case. However, I want to rule out issues with the fermentation approach, I appreciate any feedback on this part of the process.

What is your mash temperature? That is quite a bit off crystal and a bunch of other specialty malts, mashing too high with that grainbill is likely gonna cause under attenuation.

Fast Ferment Test (link)

The idea of the Fast Ferment Test is to completely ferment all fermentable sugars in a sample of wort.

 

[sarandos25]

What is the source for that recipe (book, web site)?

It's a clone of a Rogue beer; I've seen multiple versions of the clone and they all call for fermentation at 60F.

What is your mash temperature? That is quite a bit off crystal and a bunch of other specialty malts, mashing too high with that grainbill is likely gonna cause under attenuation.

First time 154.5F; second time 152.5F... should I go lower? If so what temp do you advice?

Part of the original post which no one has opined on and I still have a question is the approach to cool the rehydrated yeast, should I rehydrate at 84F, cool to pitch at 68F, and the finish bringing everything down to 60F gradually OR should I cool the rehydrated yeast all the way to 60F and pitch at that temp.

Thank you all for the input!!

Fast Ferment Test (link)

BrewnWKopperKat -I will incorporate this into our process going forward.

 

[BrewnWKopperKat]

It's a clone of a Rogue beer; I've seen multiple versions of the clone and they all call for fermentation at 60F.

Link? Is US-05 the only yeast recommended? Or are other strains recommended as well?

 

[Erik the Anglophile]

It's a clone of a Rogue beer; I've seen multiple versions of the clone and they all call for fermentation at 60F.



First time 154.5F; second time 152.5F... should I go lower? If so what temp do you advice?

Part of the original post which no one has opined on and I still have a question is the approach to cool the rehydrated yeast, should I rehydrate at 84F, cool to pitch at 68F, and the finish bringing everything down to 60F gradually OR should I cool the rehydrated yeast all the way to 60F and pitch at that temp.

Thank you all for the input!!



BrewnWKopperKat -I will incorporate this into our process going forward.

I would try 66c or even maybe 65c with that grain bill unless you have sugar in the recipe. So pretty much 150f or just below.
I'm still pretty new to brewing myself and no yeast expert, but I pitch one dry pack into about a deciliter of water that is around 30c and let it sit while I cool the wort and pour it into the fermenting bucket, 30 min or so. I think the temp of the wort you pour the yeast into is more important, since the very small amount of liquified yeast you add to it will assume the same temparature as the wort in no time.

 

[BrewnWKopperKat]

Part of the original post which no one has opined on and I still have a question is the approach to cool the rehydrated yeast, should I rehydrate at 84F, cool to pitch at 68F, and the finish bringing everything down to 60F gradually OR should I cool the rehydrated yeast all the way to 60F and pitch at that temp.

With US-05, I take the yeast out of the fridge, leave at at room temperature to warm up, then pitch it dry.

 

[sarandos25]

Is US-05 the only yeast recommended?

Wyeast 1764 Pacman is the actual yeast; I selected US-05 as what I thought would be the "best" alternative. I'm in Latin America; some of strains / brands are hard to come by, and Pacman is not available here. There is a number of alternatives listed online to Pacman, US-05 being one of them, not all available here, if anyone has something they would rather use instead of US-05, please share - I'll see if I can locate it here.

Thanks again for all the input.

 

[BrewnWKopperKat]

You're welcome.

US-05 is fine and a common substitution for 1764. I was trying to understand why the recipe was fermenting at 60F then raising the temperature.

When fermenting around 60F, I find US-05 to be sluggish, so it's possible that the yeast didn't finish in the 7 days that were specified in the recipe. I have absolutely no idea if raising the temperature on day 7 would help finish fermentation.

A fast ferment test (FFT) would help identify if the combination of US-05 and the fermentation temperature is part of the problem.

For you next attempt, you might want to try fermenting at a consistent temperature (along with a FFT) to see how long it takes for the yeast to completely ferment the batch at a stable temperature.

Given the amount of crystal, and with a warmer fermentation temperature, I would guess you are not going to get 80% attenuation. With my 20% crystal malt beers, I'm closer to 75% attenuation with US-05.

 

[Gnomebrewer]

Yeast calculators generally don't account for the grain type being used. They're crude estimates at best for beers like this. Munich and crystal will both cause a higher FG than the calculator predicts. If the beer finishes at 1.020 but doesn't taste too sweet, I wouldn't worry about it. Some of the long chain dextrins that are left don't taste sweet, so you could have a nice, malty beer without too much sweetness with a 1.020 gravity. That is a lot of crystal though, and if you get any oxygen in after pitching yeast it's going to taste cloyingly sweet.

I'm assuming the 60F ferment temp was for Pacman yeast? I'd definitely go with high 60s for US-05. No need to rehydrate the yeast if you don't want to. I do (because it's easy and I can see that it's active before it goes in) by simply adding a pack to 110mL of boiled water cooled to pitching temps, left for 30 minutes before pitching.

 

[rburrelli]

I think rehydrating the yeast and then dropping it almost 20 degrees in 90 minutes also caused a bit of shock.