Attenuation

[JustBeKind]

Hi, I have brewed probably a hundred plus all grain brews and I have never had a problem with attenuation until my last two brews which reached an attenuation of 55% and 65% respectively. I am a creature of habit and have used the same equipment, same method, same temps for mash and fermentation etc each time. Thermometer and hydrometer checked and ok. As I haven't changed any variables, I'm at a loss to understand what is happening.

The 55% was a highish OG beer but I have brewed it twice before with the same yeast and come in below my expected FG. The 65% one was a moderate OG, again a recipe and yeast I've brewed before.

My next planned brew will have a target of 6.5 ABV and uses 440g of BBC hops so I'm not going to do that one until I sort out my attenuation problem.

 

[Covrich]

what yeast is it?

 

[JustBeKind]

what yeast is it?

Mangrove Jacks Empire Ale for the stronger beer, expected attenuation 70 - 80% and MJ Liberty Bell for the lower ABV, expected attenuation 74 - 78%. I would normally reach the higher end of the attenuation range not 10 - 15 points below.

 

[Cheshire Cat]

Try different manufacturers yeast on your next brew. Sounds like stuck fermentation.

 

[Agentgonzo]

There have been a LOT of threads recently with fermentation bottoming out at 1.020. so much so that I'm wondering whether it's the yeast being supplied that has changed. A lot of them seem to be MJ yeast too. My latest batch using liberty bell finished a few points higher than expected as well.

I had an M15 brew finish at 1.020 earlier in the year. Something like 60% attenuation.

 

[Sandimas]

Mangrove Jacks Empire Ale

Oh dear....I've tried to love Empire Ale and have used it a number of times, but the results have been all over the place: best was 80%, poorest was 51%, and quite wides variations each time. I've given up with it.

Liberty Bell is much more reliable, 82-75% in all the brews I've used it in.

Describe your beers a bit more: are they darker ones? I have more issues with the darker ones, Porters and Stouts, paler ales seem to ferment out much better. I don't tent to use Liberty Bell with darker beers which might explain my better results.

 

[Cheshire Cat]

Use either CML, Saf, or Gervin yeast.

 

[JustBeKind]

Oh dear....I've tried to love Empire Ale and have used it a number of times, but the results have been all over the place: best was 80%, poorest was 51%, and quite wides variations each time. I've given up with it.

Liberty Bell is much more reliable, 82-75% in all the brews I've used it in.

Describe your beers a bit more: are they darker ones? I have more issues with the darker ones, Porters and Stouts, paler ales seem to ferment out much better. I don't tent to use Liberty Bell with darker beers which might explain my better results.

I used the Empire Ale in a 1060 Old Ale with a standard kind of grist plus some black treacle. When it bottomed out at about 1024 after two weeks, I threw in a champagne yeast and left it another week but no effect whatsoever.

The Liberty Bell went into a simple bitter projected to be about 5.5. It was at 1022 after two weeks. I left it another week and it came down to about 1020. I have never had a problem with Liberty Bell. In fact, in general my brews tend to overattenuate which is why I’m perplexed.

 

[Jim Brewster]

I was reluctant to try Empire Ale precisely because of lots of threads talking about stuck fermentations, but I've had very good results so far. I'd class it's a low attenuating yeast though.. fine when that's the aim.

 

[dmtaylor]

M15 Empire is entirely unable to ferment maltotriose. It is the lowest attenuating yeast on the market, averaging 60% for most "normal" barley worts. If you don't like that, use any other yeast.

 

[Michael Burnley]

Just to add my tuppence, I've a best bitter that has just finished, and I got a disappointing 68% attenuation with Liberty Bell.

 

[Sandimas]

It's worth remembering that houses are turning cold this time of year so if you haven't got any temp control, your brew may get too cool and stall. A garden trug and 50W fish tank heater to put your FV in is a simple, cheap solution.

Re M15, when I used it I wanted a low-attenuating yeast but I got such inconsistent results, I wouldn't mind if it was 60%ish every time but it was all over the place so impossible to plan the ABV with any accurancy.