Attenuation help with dark beers please

[guillotine]

Hi, hopefully someone can help me out with this problem as I have been disappointed with my last few brews, to point of wanting to give up brewing dark beers (which I love in the winter)

I have brewed 4 porters & stouts from Terry Fosters Porters & Stouts book; a basic Porter, Milk Stout, Oat stout, and Baltic Porter. All of which have had poor attenuation (60%-65%).

Prior to this (I started brewing Jan this year) I have been brewing Pale Ales/bitters, Lagers and Beligium beers and a Mild, all from Greg Hughes brewing book. Which looking back have an attenuation of 75%-80%.

So my question is can anyone think of why I am losing attenuation when brewing dark beers? The only link I can see is the recipe sources?

More info:
I brew all grain in the bag in 10l batches.
I mostly use dry yeast (usually Mangrove jacks) ranging from 0.5-1 pack depending upon OG.
I have recently tried stirring periodically during the mash, and leaving the mash longer, but no improvement.
I have tried adding more yeast during the primary on one occasion, but this did not improve FG only gave my lively bottles!

Thanks

 

[MickDundee]

When you say you are using MJ yeasts, are you using their dark ale yeast? I believe it has a low attenuation. Also, I may be wrong, but I think crystal and roasted grains have fewer fermentable sugars than pale base malts.

 

[terrym]

Hi, hopefully someone can help me out with this problem as I have been disappointed with my last few brews, to point of wanting to give up brewing dark beers (which I love in the winter)

I have brewed 4 porters & stouts from Terry Fosters Porters & Stouts book; a basic Porter, Milk Stout, Oat stout, and Baltic Porter. All of which have had poor attenuation (60%-65%).

Prior to this (I started brewing Jan this year) I have been brewing Pale Ales/bitters, Lagers and Beligium beers and a Mild, all from Greg Hughes brewing book. Which looking back have an attenuation of 75%-80%.

So my question is can anyone think of why I am losing attenuation when brewing dark beers? The only link I can see is the recipe sources?

More info:
I brew all grain in the bag in 10l batches.
I mostly use dry yeast (usually Mangrove jacks) ranging from 0.5-1 pack depending upon OG.
I have recently tried stirring periodically during the mash, and leaving the mash longer, but no improvement.
I have tried adding more yeast during the primary on one occasion, but this did not improve FG only gave my lively bottles!

Thanks

1. Have you tried a different 'brand' of yeast other than Mangrove Jack's, e.g. Safale or Danstar, or even in extreme, a pack of Wilko (Nottingham) ale yeast.
2. You say that you used more yeast on one occasion and found lively bottles. This suggests the primary was not finished. Why not try more yeast, especially if you are brewing high OG beers, and make sure that the fermentation has truly finished before you bottle, which usually means leaving it longer in the FV.
3. I assume you have got your fermentation temperatures under control.

 

[guillotine]

I have used other yeast brands too. For the dark beers I have been using MJ Liberty Bell, a Safale (forget which one) and MJ Bavarian Lager for the Baltic Porter.

When I added more yeast the Gravity did not move, so I assume the lively bottles were due to the extra yeast and priming sugar.

Yeah temps are good, my north facing kitchen stays between 18-20, and i have beer fridge for any lagering/conditioning

 

[terrym]

When I added more yeast the Gravity did not move, so I assume the lively bottles were due to the extra yeast and priming sugar.

OK, but to be clear I meant using more yeast at the beginning not adding more late on to try to stimulate the brew along a tad more.
And if the primary is still working it will continue to generate CO2 in the bottles, irrespective of how much priming sugar is added and yeast load.

 

[DoctorMick]

Darker malts tend to have lower fermentable sugars than pale malt so I'd expect darker beers to finish higher than pales, that is certainly my experience. Have you been putting your recipes in to any brewing software?

 

[TheRedDarren]

Brewing dark ales will give you lower attenuation if there are a lot of speciality malts in the grist.
My last porter only got 48% attenuation, mind you that did have quite an extreme grain bill.
The next time I brew it I'll add and extra 20/30% base malt to correct the attenuation to get my desired abv%.

To try and up the abv a bit you could try adding some DME to the fv and see if ups it a bit.

 

[guillotine]

I have been scaling the reicpies from the book using brewers friend, and i am hitting the recipe OG, but not getting down to the FG. I have been leaving them in primary longer then my other brews but the gravity does not budge. I believe I am already over pitching by using a whole pack of yeast for 10l?

 

[simon12]

Are you using less than 80% base malt in these recipes?

 

[wfr42]

Think both the micks hit the nail on the head. Darker beers have more specialty malts and therefore more unfermentable sugars.

I'm not sure if all brewing software takes this into account as when I've played with attenuation setting on brewers friend it appears it just calculates the fg based on the set attenuation and the calculated og.

As Darren and Simon have suggested if you want it stronger up the amount of Base malt or add some dme or candied other sugar (my inner ag brewer died a bit there....)

 

[guillotine]

Thanks,

I understand this logic, but I do not understand the published book which gives the grain bills, OG, & FG being so far out? I just checked my scaled recipes and the grain bills are the same % as the recipes.

 

[TheRedDarren]

Thanks,

I understand this logic, but I do not understand the published book which gives the grain bills, OG, & FG being so far out? I just checked my scaled recipes and the grain bills are the same % as the recipes.

Books and software vs what what actually achieve at home can have variance. There are a lot variables to consider.

Which recipes did you use? I have that book as well so I'll have a look later after work and see if I can spot anything.

I'll tag @MyQul too as he makes a lot of dark beers.

 

[MickDundee]

Books and software vs what what actually achieve at home can have variance. There are a lot variables to consider.

Which recipes did you use? I have that book as well so I'll have a look later after work and see if I can spot anything.

I'll tag @MyQul too as he makes a lot of dark beers.

Not even just books and recipes, sometimes it can vary from brew to brew with the same recipe depending on where the gains have come from, how fresh they are, fine-ness of the crush, type of yeast etc.

 

[Cwrw666]

Freshness is a big issue in achieving a low FG.
If you buy in all your grains crushed they go stale very quickly. Speciality malts are already low in fermentable sugars, but just think of all those half empty bags you've had lying around for months like we all have...
I have no problem with getting a low FG these days but it's because I'm grinding my own pale malts now. The difference is astounding.

 

[InqBrewer]

What temperature are you mashing at? That could affect the conversion of sugars and the overall attenuation too. Are you mashing warmer or cooler than you were with your pale ales etc at all?

 

[MyQul]

I think the combined forum wisdom has mentioned everything you need to be looking at.
Yeast - amounts/age/whether it's medium or high attenuator
Percentage of specialty grains
Mash Temp (also mash length & thickness can effect fermentabilty of your wort)
Grain Freshness (although personally I've never had a problem keeping crushed grain for as long as 6 weeks. Although I've started to vac pac my grain now)

 

[guillotine]

Thanks all,

Looking back at the recipes the 2 worst performing (Cream Crackered stout, and Hamertoinan Oatmeal stout) have low % of base malts, whilst other recipes have a much higher % of base malts. So maybe I picked some 'harder' to mash recipes.

As for temp I follow the recipes and my tun is insulated so it stays quite constant, is a lower temp better for speciality grains? and does a longer mash help?

For freshness I use the Get 'er brewed custom grain kits so the grains are used within a weeks of delivery

 

[guillotine]

As I finish drinking my Dark beers I thought I would feedback and give thanks as after the advice above I selected brews using less specialist malts, and had some great results with Greg Hughes Dark American Larger, Terry Foster's Dam Good Stout & Nevesky Prospect Imperial Stout.

So in conclusion its worth looking at the ratio of base malts to specialist malts

Thanks all

 

[TheQuokka]

I'm a bit of a fan of heavier beers, especially at the moment as I need to prepare for winter.

I suspect your main problem is a poor choice of yeast for this style. Brewer's Friend does warn you that your mash efficiency will be lower for this style and you need to be careful of your mash pH, but the wrong yeast will often stick with these beers and you did mention problems in the bottles.