Recent beer with High FG 1025

[timtoos]

Hi,

I made the BreewUK Velveteen Choc Stout on 21/8/16 with the London III ale.

I only got the kit and yeast the other week so everything was fresh. I made the yeast up with a 1.1L starter (and stir plate) and the wort produced was 20 litres (23 - 3L loss to transfer) @ 1.054.

After I had initially mashed in I noticed the temperature was at 70C. Not sure it was a finger set point problem which I did not notice but I had mashed in already. I added about 0.7L of cold water to reduce the temperature back to 65C.

I then followed the included mash procedure which was 65C for 60 mins then mash out of 77 for 10 minsI aerated the wort for 10-15 minutes with a pump and sterile filter with stone.

Fermentation started very quick as expected. However it seems to have now stalled. Its stuck at about 1.025 and seems to have totally. Its been at this gravity since Wednesday.

I have gently swirled the FV to kick the yeast back into suspension. The FV is temperature controlled and is set at 20C - and I have cross checked this with an hand held thermometer and its correct.

I have checked today and the gravity is still the same.

This is the first time I have also tweaked my water. I was expecting great results
Any advice?

[Dave S]

How long was it a 70C for? Beta amylase doesn't like it that warm, though it can usually survive for short periods. You might have upset the balance in favour of alpha amylase.

[timtoos]

Maybe 5 minutes.

Thats what I thought. If the damage is done (which it looks like) then Ill tip it and chalk it as a 'must definitely double check my settings'.

[BenB]

Would 70 degrees really denature the enzyme within 5 minutes? It's not that far off some target temperatures... How are you checking the SG? Hydrometer? The last "stuck ferment" we had turned out to be use of a hydrometer post fermentation (without correction)..... Does it taste like 1.025?

[timtoos]

Im testing using hydrometer and refractometer. Both are reading very similar. Its tastes ok but definitely lots of residual sugars still there which haven't been fermented out.

[gr_baker]

I brewed an IPA using that yeast earlier this year and I had exactly the same experience. OG was 1060, fermentation happened very quickly but stopped at 1022. I'm pretty sure that I mashed at 66C. I've never used the yeast before so I can't say if it's normal but the guidance notes for the yeast do say that it finishes slightly sweet.

I actually put the beer in a king keg and left it in the garage. After 4 months the sweetness has subsided a bit but it's still far too sweet for the style.

Russell

[Rhodesy]

I brewed this kit the other week however I used US-05 to try and dry out a little however it finished at 1.022 having not budged for 5 days and not the predicted 1.017. I am keg priming it just now and will leave it to mature until Christmas, hopefully won't be overly sweet. Obviously the Lactose bumped up the unfermentables but I did think it would finish lower, hey ho.

[Rubbery]

Would 70 degrees really denature the enzyme within 5 minutes? It's not that far off some target temperatures...

When an enzyme is denatured it happens quickly. I sparge out regularly at 75C in order to denature alpha and beta amylase instantly. 70C is borderline for beta amylase.

[Capped]

I must be cutting it real fine as I routinely mash at an indicated 68-69C and the ale comes out all the better for it. Mind you I only mash for 45mins these days. Still end up with FGs of around 1010 - 1012 with OGs of 1045 - 1050. There's always the possibilty that my thermometer is dodgy, I suppose...

[timtoos]

I guess Ill leave it sitting where it is for the rest of the fermentation period. Maybe it will be decent at Christmas - failing that a present