Yet another relatively high FG question.

[mirsultankhan]

OG 1052
FG 1013

actual FG 1016/17

Recipe was a Fullers London Porter style

The original gravity with a brewhouse efficiency of 75 percent was predicted and measured 1052 based on the recipe and yet its final gravity seems rather high at 1016/17. I am a little worried because its been in the FV for about two weeks and although I cannot say for sure if fermentation has stopped, its certainly very slow. I used S-04 yeast and just pitched it onto the wort directly without rehydrating. I have two questions.

1. If it stays at 1016 what will happen if I prime and bottle it?
2. What alternatives are there to get it lower? adding another packet of yeast? or simply giving it time?

many thanks for taking the time regards Robbie:hat:

 

[Brewtus]

Given that this is a porter, are we to assume a reasonably high percentage of less fermentable sugars? Chocolate, roasted barley, crystal etc, if so, along with the reasonably low attenuation of SO4, 1016 probably isn't too bad, I have an Extra IPA with SO4, which finished up at 1022 (albeit with a much higher starting gravity of 1072) and no bottle bombs. If it is stable for 3 days, go for it!

 

[Slid]

Hi Robbie

If you are stuck, and really feel it should go lower, I would try racking it carefully, adding maybe 50g table sugar and warming it up a bit. That could be wrapping it in a towel or something, and leaving another week.

Except for the brews I made during the height of the summer last year, I seem to get farily good conversions (attenuations) from the same yeasts everyone else uses.

Starting low-ish temps and finishing slightly higher temps seems to equate to better conversion. Starting fermentation at a high temp seems to be a virtual guarantor of poor conversion. And poor beer.

 

[mirsultankhan]

Hi Robbie

If you are stuck, and really feel it should go lower, I would try racking it carefully, adding maybe 50g table sugar and warming it up a bit. That could be wrapping it in a towel or something, and leaving another week.

Except for the brews I made during the height of the summer last year, I seem to get farily good conversions (attenuations) from the same yeasts everyone else uses.

Starting low-ish temps and finishing slightly higher temps seems to equate to better conversion. Starting fermentation at a high temp seems to be a virtual guarantor of poor conversion. And poor beer.

Hi Slid, its quite interesting I made an oatmeal stout a week later but used Nottingham ale yeast, rehydrating according to the manufacturers instructions. It took off like nothing I have ever seen, that yeast loves beer! Both FV's were kept in the same room (actually a little cupboard in the back hall) its fairly warm in there maybe about 18-22's because its where the central heating boiler is. However at night central heating is not on and I wondered if the colder temperatures or perhaps the fluctuation in temperature had some adverse effect. Perhaps I should pay more attention to keeping beer at a constant temperature.

I think its great advice to start at lower temperature. I have heard that a long slow fermentation is to be much preferred.

many thanks for taking the time - regards Robbie

 

[mirsultankhan]

Given that this is a porter, are we to assume a reasonably high percentage of less fermentable sugars? Chocolate, roasted barley, crystal etc, if so, along with the reasonably low attenuation of SO4, 1016 probably isn't too bad, I have an Extra IPA with SO4, which finished up at 1022 (albeit with a much higher starting gravity of 1072) and no bottle bombs. If it is stable for 3 days, go for it!

Yes Brewtus, here was the grain

Pale Malt (Maris Otter) 4230g
Brown Malt 665g
Crystal Malt 555g
Chocolate Malt 110g

Could this account for the higher percentage of less fermentable sugars? I put all of the details into brewers friend and should have an FG of 1013, but if its stable i will take the advice and just go for it. Many thanks for taking the time - regards Robbie.

 

[Brewtus]

Hmmm, I'm not sure how fermentable brown malt is. But given the rest of your grain bill, I wouldn't be surprised at your FG being around that point or even higher with SO4.

What temperature did you mash at?

 

[mirsultankhan]

Hmmm, I'm not sure how fermentable brown malt is. But given the rest of your grain bill, I wouldn't be surprised at your FG being around that point or even higher with SO4.

What temperature did you mash at?

Mash temperature was 67.7 at the beginning and dropped to about 65.8 after an hour. Is SO4 not a particularly vibrant strain of yeast? would I be better pitching two packets? or making a starter with DME?

 

[TartanSpecial]

I'm brewing that (almost) exact same porter recipe just now...but using Mangrove Jack Newcastle yeast and stopped at 1:024...so have re-pitched with a starter of some Nottingham (GV12) and currently at 1:020..but seems to have stopped again.. For that recipe and Saf04 I think 1:016 isn't too bad...right now I'd be happy with that.

 

[mirsultankhan]

I'm brewing that (almost) exact same porter recipe just now...but using Mangrove Jack Newcastle yeast and stopped at 1:024...so have re-pitched with a starter of some Nottingham (GV12) and currently at 1:020..but seems to have stopped again.. For that recipe and Saf04 I think 1:016 isn't too bad...right now I'd be happy with that.

You know what TartanSpecial I been doing some reading, all those American dudes say that anything above 1040 we should definitely be making a yeast starter. I wonder if that's the reason? the cell count just wasnt enough for a thorough and clean fermentation where the yeast was able to eat up all those fermentable sugars. Did you pitch a starter at the beginning?

 

[TartanSpecial]

Hi MSK, I think the Americans all use starters for beers over 1:040 because they are usually using liquid yeast...and one vial of liquid yeast has a lower cell count that a typical 11grm pack of dried yeast. I pitched 2* 11 gram packs of Mgrove Newcastle rehydrated in water (no dextrose to avoid osmotic shock during the rehydration phase), and made sure my wort had been well oxygenated and it took off like a rocket and was finished in a couple of days...unfortunately at 1:024. Recently I've had equal success pitching with rehydrated 11 or 2*11grm packs or starters. I think the cell count with your 11grm rehydrated saf 04 is unlikely to be the problem. I think it may be the unfermentables. I did my mash at 65.5 C to try to avoid too many unfermentables (to offset the Newcastles moderate attenuation) but now I'm wondering if my thermometer isn't accurate or I got my mash ph wrong. Graham Wheelers book where that recipe appears has an FG of 1:014 so I think your 1:016 is good.

 

[Brewtus]

Mash temperature was 67.7 at the beginning and dropped to about 65.8 after an hour. Is SO4 not a particularly vibrant strain of yeast? would I be better pitching two packets? or making a starter with DME?

As others have said, nothing wrong with SO4, just not naturally very highly attenuating, coupled with a reasonably high initial mash temperature, which will extract a higher proportion of unfermentable sugars, and your grain bill with it's unfermentables, again, 1.016 isn't bad at all. Also a higher FG is generally good for a porter to give that rich full bodied mouth feel.

 

[mirsultankhan]

Hi MSK, I think the Americans all use starters for beers over 1:040 because they are usually using liquid yeast...and one vial of liquid yeast has a lower cell count that a typical 11grm pack of dried yeast. I pitched 2* 11 gram packs of Mgrove Newcastle rehydrated in water (no dextrose to avoid osmotic shock during the rehydration phase), and made sure my wort had been well oxygenated and it took off like a rocket and was finished in a couple of days...unfortunately at 1:024. Recently I've had equal success pitching with rehydrated 11 or 2*11grm packs or starters. I think the cell count with your 11grm rehydrated saf 04 is unlikely to be the problem. I think it may be the unfermentables. I did my mash at 65.5 C to try to avoid too many unfermentables (to offset the Newcastles moderate attenuation) but now I'm wondering if my thermometer isn't accurate or I got my mash ph wrong. Graham Wheelers book where that recipe appears has an FG of 1:014 so I think your 1:016 is good.

Yes that makes real sense and I always kind of wondered why our American cousins use slap packs and liquid yeast. There is a cell count calculator that comes with brewers friend which estimated that I was short given the specified parameters of about 112 billion cells.

Cells Available: 110 billion cells
Pitch Rate As-Is: 0.37M cells / mL / °P
Target Pitch Rate Cells: 222 billion cells
Difference: -112 billion cells
Needs starter (see below), or more yeast.

How accurate this is I do not know but its perhaps worth experimenting with. Even a starter made just 24 hours prior to pitching, just to see if it makes any discernable difference.

 

[mirsultankhan]

As others have said, nothing wrong with SO4, just not naturally very highly attenuating, coupled with a reasonably high initial mash temperature, which will extract a higher proportion of unfermentable sugars, and your grain bill with it's unfermentables, again, 1.016 isn't bad at all. Also a higher FG is generally good for a porter to give that rich full bodied mouth feel.

Thats very reassuring. I took your advice Brewtus and just went for it, its in the bottles and conditioning as we speak. Many thanks for taking the time your knowledge and experience is very helpful.