Stuck Fermentation - Advice!

[hill1649]

I brewed 6.5 litres of a Raspberry Gose on 20.07.21 using a different recipe from normal (see below) - all went well, got the expected 1.043 SG, aerated well and added a pack of Mangrove Jacks's M21 Wit Yeast. Fermentation took off (it was VERY hot in the house - 25-27 degrees). On 23.07.21 I checked the SG - down to 1.016 - and I added the Raspberries. Have just checked the SG today (25.07.21) and it is still at 1.016 - all the flavour and colour from the raspberries has been absorbed by the beer so I've removed them. Ideally, I want to be hitting an SG of 1.010 - 1.012 maximum. Any suggestions on my best options? Obviously, I could leave it a few days and then bottle but it would only be a 3.5% beer! It is definitely very cloudy but I would expect this with a beer with so much wheat in it especially with the added raspberries!

Here's the recipe for 6.5 litres:
500g Maris Otter Pale Malt (36.4%)
500g Wheat Malt (36.4%)
100g Torrefied Wheat (7.3%)
275g Acidulated Malt (20%) - Added after 60 minute mash and then mashed for further 45 minutes

3g Nelson Sauvin Hops - 60 minute boil
6g Coriander seed lightly crushed - 10 minute boil
3g Sea Salt - 10 minute boil

350g de-frosted Raspberries in secondary

 

[The Baron]

Could it be the acid content in the raspberries that may have affected the yeast in its less active mode? just a thought.
Apart from that do the usual like rousing the yeast with a stir putting it in a slightly warmer place to try and getting it going again or maybe a bit of yeast nutrient just to try to get that extra point or 2 if not just go with it and keg/bottles

 

[Sandimas]

Given that you only pitched the yeast 5 days ago I'd be tempted to leave it and let it do it's thing, then check it again around Day10-12.

I've had brews stall with a high FG if fermented hot so it could be that. But sometimes it just happens and it can be hard to track down. In my experience it's nigh-on impossible to re-start a brew and get it right down to target FG around 1010, most of the fermentables have already been used up: you may get an extra few points out of it. Happy to be proved wrong, but I'm northwards of 200 brews and have never managed to re-start a brew and get it right down.

 

[peebee]

But is it stuck? Adding them raspberries will increase the sugar, which the yeast will set upon (leftover malt dextrin is hard work by comparison). By coincidence the SG might have dropped back to 1.016 again when you measured it? Might be dropping some more in a while?

... In my experience it's nigh-on impossible to re-start a brew and get it right down to target FG ...

Good to know! I haven't any experience of "stuck" fermentation in 45 years of brewing. But may last brew stopped at 1.027 and my attempt to restart has gone no-where. I was doing some unconventional larking about with it (emulation of historical beers, expected a high FG at 1.018 anyway), so I'll just go with what I've got and stop mucking about with it!

 

[dmtaylor]

20% acidulated malt might put your yeast to sleep! Acid will keep organisms at bay, including your own yeast if you go overboard like this. I would not have used any acidulated in a raspberry beer where the fruit itself is very tart.

The sea salt could have had the same effect, yeast don't like that much salt. It would be better to reserve the salt for the last day when you bottle or keg, add a little at a time to taste.

The fermentation is probably not stuck anyway. While the yeast are not happy, this is a fussy yeast to begin with. My experience with this yeast is that it will attenuate to about 80%....... but it takes about 3-4 weeks to get there. It's only been 5 days so far! Perhaps all you really need is patience. Leave the beer alone now for another 3 weeks or more. The yeast will likely continue to work very very slowly... especially given the acid and salt conditions for an already finicky yeast strain.

 

[hill1649]

20% acidulated malt might put your yeast to sleep! Acid will keep organisms at bay, including your own yeast if you go overboard like this. I would not have used any acidulated in a raspberry beer where the fruit itself is very tart.

The sea salt could have had the same effect, yeast don't like that much salt. It would be better to reserve the salt for the last day when you bottle or keg, add a little at a time to taste.

The fermentation is probably not stuck anyway. While the yeast are not happy, this is a fussy yeast to begin with. My experience with this yeast is that it will attenuate to about 80%....... but it takes about 3-4 weeks to get there. It's only been 5 days so far! Perhaps all you really need is patience. Leave the beer alone now for another 3 weeks or more. The yeast will likely continue to work very very slowly... especially given the acid and salt conditions for an already finicky yeast strain.

20% acidulated malt might put your yeast to sleep! Acid will keep organisms at bay, including your own yeast if you go overboard like this. I would not have used any acidulated in a raspberry beer where the fruit itself is very tart.

The sea salt could have had the same effect, yeast don't like that much salt. It would be better to reserve the salt for the last day when you bottle or keg, add a little at a time to taste.

The fermentation is probably not stuck anyway. While the yeast are not happy, this is a fussy yeast to begin with. My experience with this yeast is that it will attenuate to about 80%....... but it takes about 3-4 weeks to get there. It's only been 5 days so far! Perhaps all you really need is patience. Leave the beer alone now for another 3 weeks or more. The yeast will likely continue to work very very slowly... especially given the acid and salt conditions for an already finicky yeast strain.

The acidulated wheat was the only experimental part of this beer - that's why such a small run. My understanding with a Gose is that you add the salt and coriander in the last 10 minutes of the boil in order to mimic the water and beer style. Neither of these or the Lactobacillus (previous souring agent) have been problematic in the past either. The PH was nothing like as low as my previous Gose brews! I don't know - could have been an oldish batch of yeast - although it was in date, could have been the heat, could have been the acidulated malt, could have been all or none of the above! Normally my beers are done and ready for bottling or barreling within 5 days - clearly, this one is going to take longer! It kind of tastes okay - just would have liked it a bit stronger - not sure how long a 3.5% beer will last!

 

[hill1649]

But is it stuck? Adding them raspberries will increase the sugar, which the yeast will set upon (leftover malt dextrin is hard work by comparison). By coincidence the SG might have dropped back to 1.016 again when you measured it? Might be dropping some more in a while?



Good to know! I haven't any experience of "stuck" fermentation in 45 years of brewing. But may last brew stopped at 1.027 and my attempt to restart has gone no-where. I was doing some unconventional larking about with it (emulation of historical beers, expected a high FG at 1.018 anyway), so I'll just go with what I've got and stop mucking about with it!

Good point! I didn't think to check the SG straight after adding the raspberries!

 

[hill1649]

Thanks everyone - going to try and exercise some patience!

 

[peebee]

…

… In my experience it's nigh-on impossible to re-start a brew and get it right down to target FG …

Good to know! I haven't any experience of "stuck" fermentation in 45 years of brewing. But may last brew stopped at 1.027 and my attempt to restart has gone no-where. I was doing some unconventional larking about with it (emulation of historical beers, expected a high FG at 1.018 anyway), so I'll just go with what I've got and stop mucking about with it!

Hey, not so "impossible"! But I'm probably on the unlikely side of "nigh-on", I'm certainly restarting from a higher "stuck" gravity and hoping for a high FG anyway (I'm now worried it will overshoot; one of my mucking about actions was adding 1/2 pack of more aggressive yeast - S-04, is more aggressive than S-33 - along with rousing - that's rousing, not a very bad aerating and thrashing with a spoon!):

Trace from a TILT hydrometer. The beer has shifted down two points in the last 24 hours, but you can see the disturbance of rousing almost a week ago (US daft date format) - unsticking needs patience!

Ignore the erratic day/night temperature trace. The TILT is on the surface, the (steady) cooling controller probe is at the bottom (Grainfather conical). Good example of how temperature probe placement can tell lies.

 

[peebee]

Not "impossible" to restore a stuck fermentation? Five days on and my "stuck" beer that had, with a bit of patience, started to move down again moving from 1.027 to 1.025. And now ...

It's at 1.025! Patience run out. As @darrellm said, it's nigh on impossible to re-start a brew and get it right down to target FG. The beer is getting casked now whatever gravity it's at.

 

[hill1649]

Not "impossible" to restore a stuck fermentation? Five days on and my "stuck" beer that had, with a bit of patience, started to move down again moving from 1.027 to 1.025. And now ...

It's at 1.025! Patience run out. As @darrellm said, it's nigh on impossible to re-start a brew and get it right down to target FG. The beer is getting casked now whatever gravity it's at.

Yep, just checked my SG today and it is now down to 1014! Will give it another few days and then bottle! Tastes okay, just not very alcoholic but maybe it's good to have a weaker beer alongside the 6.5%ers!

 

[Sandimas]

Not "impossible" to restore a stuck fermentation? Five days on and my "stuck" beer that had, with a bit of patience, started to move down again moving from 1.027 to 1.025. And now ...

Yes, that's my experience too: I've managed to shift mine about 2 points on some occasions after rousing and adding a bit of sugar, but no more.

I bottled my last one that did this at 1025 and it was one of the best beers I've ever made, and it didn't re-start in the bottles so no problem with bottle bombs.

 

[hill1649]

Yes, that's my experience too: I've managed to shift mine about 2 points on some occasions after rousing and adding a bit of sugar, but no more.

I bottled my last one that did this at 1025 and it was one of the best beers I've ever made, and it didn't re-start in the bottles so no problem with bottle bombs.

Did you prime the bottles? I do want a bit of fizz but don't want the beer overly sweet.

 

[peebee]

Yes, that's my experience too: I've managed to shift mine about 2 points on some occasions after rousing and adding a bit of sugar, but no more. ...

12 days after the attempted "resurrection" of my stuck fermentation and the flippin' stuff has kicked off again!

I think this is the "more aggressive" S-04 addition eventually having an effect. Remember, "more aggressive" than the S-33 originally used that is.

No thanks to me and "patience". My patience ran out ages ago and the beer is only still in the fermenter (and not a keg) because I've been too lazy to get the job done. I now have to worry the fermentation will overshoot my intended FG (1.018 - 1.019), I've already dropped the temperature to encourage it to stop.

On the subject of temperature: Notice how it settles down (red line) when fermentation restarts? This output is from a Tilt floating on the surface not the controller submerged near the bottom.

Did you prime the bottles? I do want a bit of fizz but don't want the beer overly sweet.

Do remember "dextrin" (long chain sugars left until near the end of fermentation) are not as sweet as sugars like maltose and glucose. But "dextrin" is "heavier" and probably not appropriate in a lighter "keg" or bottled beer. Don't mix up "Dextrin" with "Dextrose", that's and unfortunate quirk with the language.

I'd always prime bottles (with table sugar; sucrose) but always ensure the beer has fermented out beforehand (tricky if suspected of being "stuck").

Different yeasts handle dextrin differently (from refusing to touch the stuff to fermenting it completely out with hardly any hesitation - "Saison" yeasts is a good example of the latter).

 

[hill1649]

We'll, finally dropped to SG 1010/1011 so I've bottled some and barrelled the rest - tastes okay but not as sour as I'd like so will probably go back to my original recipe using lactobacillus rather than than the acidulated malt! I guess experimentation is what makes the home-brewing experience fun! Hopefully the warm weather will return so I can enjoy drinking this fruity Gose in the sun!

 

[peebee]

We'll, finally dropped to SG 1010/1011 ...

Blast! I'm catching up with you!

I did want it to stop at 1.018. I think that S-04 was a mistake? But if it wasn't added it will probably stayed at 1.025 as @darrellm predicted. Still, those Tilts can be fairly unreliable for FG, might not be so low?

Mine won't be ready to drink "in the sun"; needs 2-3 months in the cask. It's not a sunny weather beer anyway, it's a "I think there's snow on the way" beer.

 

[hill1649]

Blast! I'm catching up with you!

View attachment 51959

I did want it to stop at 1.018. I think that S-04 was a mistake? But if it wasn't added it will probably stayed at 1.025 as @darrellm predicted. Still, those Tilts can be fairly unreliable for FG, might not be so low?

Mine won't be ready to drink "in the sun"; needs 2-3 months in the cask. It's not a sunny weather beer anyway, it's a "I think there's snow on the way" beer.

Beer, don't you just love it! Those yeasties just have a mind of their own!