BIAB porters and stouts FG too high

[jonny1000]

Hi all,

This is my first post and while I have seen similar topics in this and other forums, there hasn't been anything that has really answered my question.

I am from England but live out in Taiwan and have been brewing using Brew in a Bag for the last year, with varying success. The beer style I always come unstuck on though is porters / stouts or anything with a higher than usual degree of unfermentables.

For example, I have brewed a schwarzbier, porter and oatmeal stout. I haven't been able to get any of these recipes under a 1.020 FG, which has left them, although pretty tasty, sweeter than planned. This hasn't happened with any other style where I have always had an FG between 1.006 and 1.016. I have seen various 'fixes' for this issue (re-pitch yeast, stir to get the yeast back into circulation) and a few comments that if it tastes ok then I shouldn't worry but nothing which addresses why this happens and how to avoid in the future.

I will post the porter and oatmeal stout recipes as I tried to correct some things with the oatmeal stout. For example, I added more base malt, tried to stop the temp from dropping too much in the mash, added a mash out step, switched back to pitching yeast directly into wort before aerating, and did a longer boil. If anyone can give some advice it would be greatly appreciated. Cheers!

Porter

German Pale Ale malt x 4.0kg
Chocolate malt x 0.3kg
Black malt x 0.2kg
Roasted barley x 0.2kg

Perle T-90 28g (added after 5 mins)
EK Goldings T-90 28g (added 5 mins before end of boil)

75 min mash, starting at 67 degrees C and dropping to 61 degrees C
80 min boil

Danstar nottingham dried yeast, rehydrated in 100ml of water following instructions on website

OG - 1.051
FG - 1.023


Oatmeal stout

German pale ale malt x 4.4kg
Flaked oats x 0.25kg
Crystal malt x 0.2kg
Chocolate malt x 0.15kg
Roasted barley x 0.07kg

Admiral T90 28g (added after 15 mins)
Northern Brewer 28g (15 mins before end)

60 min mash at 67 degrees C (there was some fluctuation of +/- 3 degrees as I used a flame to try to maintain this temp) plus 10 min mashout at 75 degrees C
90 min boil

Safale S-04, dried packet, sprinkled directly into wort

OG - 1.060
FG - 1.022

 

[Mark1964]

the recipe looks fine. Have you tried these recipes with a liquid yeast or something different to Nottingham? Welcome to the forum too

 

[stesmi]

Hi jonny1000

I'm not sure I can add anything about 'fixes' that you've not been told before, but in the future try a BIG yeast starter. I know people say there's no need with dry yeast, but i think it'll be worth a try? Or if OG is pretty high then water down to get 1.048. High OG shouldn't be a problem for Nottingham or S-04, but if it's older yeast, then maybe it's struggling at 1.06 OG?

 

[jonny1000]

Thanks,

I used Safale S-04 instead of Nottingham for the oatmeal stout and that didn't make a difference. I have never used liquid yeasts but, living in Taiwan, supplies are limited and it is hard to get hold of liquid yeast in small quantities.

I can try to get hold of liquid yeast but the dried packets should be able to do the job, right? As I say, no problem with my pale ales, amber ales, IPAs etc.

 

[jonny1000]

Thanks Stesmi,

I have never tried a yeast starter for two reasons, though I know that it is best practice to do so. The main reason (aside from laziness) is that I can't get hold of DME here, although I think you can make a starter without DME, right?

There shouldn't be a problem with the age of the yeast. It is always vacuum packed and has a best before date which has never gone over.

Also, the porter only had a 1.051 OG and that still had the same problem so not sure watering down for a lower OG would help.

 

[jonny1000]

Incidentally, I just went on my brewing suppliers website and noticed they have started to stock yeast nutrients. Maybe that will help for the next batch? Seems like it would be worth a try.

 

[MyQul]

I think yeast nutrient would help quite a lot.

As for starters and getting hold of DME, if you dunk sparge your grain after you've finished your brew, you can use those runnings for starters, just boil it down/dilute it to 1.040.

You could also try harvesting your yeast. Just rinse a yeast cake and repitch

The other 'fix' you might like to try is to add/replace some of the base malt with white table sugar as the yeast will munch through all of this and get your FG to where you want it

 

[stesmi]

Incidentally, I just went on my brewing suppliers website and noticed they have started to stock yeast nutrients. Maybe that will help for the next batch? Seems like it would be worth a try.

Hopefully, yes. Yeast starters can be a pain, you're right. Btw you can make a mini mash instead of dme for a starter. The mini mash wort can be frozen and used whenever - just a thought :nah:

 

[jonny1000]

Thanks guys, I will definitely use the nutrients next time and look into doing a yeast starter too. Does it matter if the yeast cake is from a different style of beer? For example, can I use the yeast cake from my oatmeal stout to pitch into the jasmine tea pale ale I am going to brew tomorrow?

 

[MyQul]

Ideally you want to pitch a yeast cake from a pale beer into a dark one rather than the other way around as it may be possible to pick up some flavour/colour from the dark yeast cake.

But you can wash/rinse the yeast cake to get rid of the old beer and trub. Have a look at a couple of youtube vids on how to do it