[Attik]

Hi everyone,

I am currently in the process of brewing my first all grain russian imperial stout and I need some help. My main doubts are with regards to the fermentation process. Below is the data I have collected before fermentation and three weeks after:

OG: 1095
pH: 5.1
Temperature: 16 degrees celcius
Yeast: Mangrove Jacks M07 British Ale

Afer 3 weeks

Measured Density: 1034
pH: 4.6
Fermentation temperature: 16 degrees celcius

My questions are the following:

1. Should I let the beer keep on fermenting for another week?
2. Should I transfer the beer into another fermenter and begin a secondary fermentation process? I was thinking of adding some oak chips - How much would be advisable?
3. This might seem a bit strange but should I add a bit of yeast in the secondary fermentation to drop the final gravity further?

[HoosierBrew]

Hi everyone,

I am currently in the process of brewing my first all grain russian imperial stout and I need some help. My main doubts are with regards to the fermentation process. Below is the data I have collected before fermentation and three weeks after:

OG: 1095
pH: 5.1
Temperature: 16 degrees celcius
Yeast: Mangrove Jacks M07 British Ale

Afer 3 weeks

Measured Density: 1034
pH: 4.6
Fermentation temperature: 16 degrees celcius

My questions are the following:

1. Should I let the beer keep on fermenting for another week?
2. Should I transfer the beer into another fermenter and begin a secondary fermentation process? I was thinking of adding some oak chips - How much would be advisable?
3. This might seem a bit strange but should I add a bit of yeast in the secondary fermentation to drop the final gravity further?

I wouldn't rack yet. Big beers take a while to drop those last few gravity points. I'd carry the fermenter to the warmest room in the house and let it sit for a week. This might spur the yeast to eat a few more points. But you should post your recipe and process so we can be more help.

[fmader]

Yeah. Leave it on the yeast. Remember that you shouldn't be determining that the beer will be done in three weeks. The beer will tell you when it will be done.

[dilluh98]

I'd go another 2 weeks at higher temps before checking the gravity again. I'd be surprised if you didn't knock off at least a few more points.

[brewinhard]

+1 to the above comments.  Don't be afraid to give your stout a good swirl to help rouse the yeast a bit in addition to moving the fermenter to a warmer spot.  Getting up to 70-75F is no big deal at this stage in the game.

[Attik]

Hi everyone, as requested please find the recipe and brewing process below:

Malts
15.4kg Matis Oter (5.9 EBC)
0.5kg Caramel/Crystal (150 EBC)
0.5kg Chocolate Malt (886.5 EBC)
0.44kg Biscuit Malt (45.3 EBC)
0.44kg Cara-Pils/Dextrine (3.9 EBC)
0.29kg Roaster Barley (1250 EBC)
0.20kg Black Barley (985 EBC)

Hops
92.6gr Target (11 %) @ 60mins
46.3gr Admiral (14.75%) @30min
4pqts British Ale Yeast Mangrove Jack M07

Mash

Simple Infusion + Mashout: 66 degrees then 78 degrees with a total of 52 litres of water. (29 litres for the infusion and 23 litres of boiling water for the mashout to increase the temperature)
Mash pH: 5.6

Sparge

Sparge with 17 litres of water at 73 degrees.
Final density after sparging: 1044

Boil

Pre-boil density 1063
Pre-boil pH 5.5
Pre-boil volume: 47 litres
Post-boil volume: 30 litres

Fermentation

Volume: 28 litres
Density: 1095
pH: 5.1

After 29 days of fermentation

Density: 1034
pH: 4.2
Fermentation temperature: 12-15 degrees celcius. Sometimes a little colder

Should I keep on waiting or should I proceed to bottling?

Thanks in advance!

[dilluh98]

Your fermentation temperature seems a bit on the low side and I wonder if things aren't a bit sluggish because of that. 1.034 at this point in the game seems high. I'd probably try to bump it up to 20-22 C and give it a good swirl.

[JJeffers09]

you are sitting at below optimal fermentation temps for that ale yeast strain, 12-15C or 53F-59F and the packaging tells you 14C-22C or 57F-72F.  All yeast performs better at higher temps, but I would say you need to sit at the 18C-20C range to kick your yeast off again, but I am really wanting to know your pitch rate.  Hopefully you did a starter with a 1.095 starting wort. A ProBrew Pitch rate of 1.0B/mL/D. Plato would be ideal.  What was your pitch amount or slurry amount? hopefully not a single package pitched directly to the fermenter.

[RPIScotty]

you are sitting at below optimal fermentation temps for that ale yeast strain, 12-15C or 53F-59F and the packaging tells you 14C-22C or 57F-72F.  All yeast performs better at higher temps, but I would say you need to sit at the 18C-20C range to kick your yeast off again, but I am really wanting to know your pitch rate.  Hopefully you did a starter with a 1.095 starting wort. A ProBrew Pitch rate of 1.0B/mL/D. Plato would be ideal.  What was your pitch amount or slurry amount? hopefully not a single package pitched directly to the fermenter.

I think you meant 1 x 10⁶/mL/°P


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[JJeffers09]

I did mean M.  This is what I am seeing as what you need for the calculator that I use... 

http://www.brewersfriend.com/yeast-pitch-rate-and-starter-calculator/

Let me know if this helps.

[Attik]

With regards to the yeast we directly poured 3 packets of yeast into the fermenter without a starter. According to the calculator in Mr. Malty this amount was adequate, although we did not use a starter

[RPIScotty]

Depending on which set of numbers you subscribe to for pitch able dry yeast amounts, and referencing Mangrove Jack's website, you pitched anywhere from:

5 x 10⁹ cells/g * 10g * 3 = 150B cells

to

20 x 10⁹ cells/g * 10g * 3 = 600B cells

If you didn't rehydrate then you may fall somewhere in the middle of that range.

Technically speaking you would require, if using 1 x 10⁶ cells/mL/°P as a pitch rate:

1,000,000 * 28* 22.5 = 630 x 10⁹ cells

You likely under pitched. Did you aerate well?

     



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[JJeffers09]

Yeah you are under pitched, at 23.75 Plato you only pitch .43M/mL/P or ~300 Billion cells total depending on how fresh the yeast was.

Mr. Malty says that you have around 20 Billion cells per gram and nowhere to my knowledge does that get supported, studies done show per gram on a variety of yeast strains are pretty inconsistent. 8-18 billion per gram on dry yeast based on a number of factors. 

***from: Van Den Berg, S., & Van Landschoot, A. (2003). Practical use of dried yeasts in the brewing industry. CEREVISIA, 28(3), 25-30 (Table 1).***

You should have made a slurry off of those 3 packets, and allowed them to go bananas in a starter at about 2L ~12.5P or 1.050 SG  Then you would have hit a reasonable to target pitch rate.  You should be able to pitch some more yeast on your beer.  You may want to rack to a secondary and really re-energize you wort with some nutrients with your second pitch.  Only if you have reason to suspect there is dead yeast flavors in your beer should you go to a secondary.  (Or some other reason that someone else could speculate.)

Oh, and seriously pick up the habit of using starters.  It has helped me out, hopefully it will help you out.

[Attik]

Would it make sense to add another yeast package in a secondary fermentation to finish off? If so, would it affect flavourwise or anything?

[JJeffers09]

  You should be able to pitch some more yeast on your beer.