Stopping fermentation

[schmurf]

I've got a brew of a dark mild going and I'm noticing that the FG are going to be lower than expected, I.e. yeast will attenuate more than calculated. Reason for this is most likely my mash schedule. Anyway, I will let this one ride out but it got me thinking how I should act, if it's possible, to halt the fermentation as the expected/wanted FG is being reached. Is there a common practice for this, to "rescue " a fermentation that seems to attenuate more than you want?

 

[thehaze]

What's the recipe, OG and expected FG? What yeast did you use?

You can kill the yeast with some sulfites or something, but you will need to add yeast to carb it up ( if you bottle ). It's easier if you keg.

 

[schmurf]

It's orfys mild mannered ale and I'm using bulldogs English ale B4.... never used it before but should according to the package attenuate to 65-70%. I'm at 75% at the moment.

Yes I'm kegging btw.

 

[schmurf]

Wouldn't killing the yeast with sulfites have other unwanted consequences, such as it not being able to clean up diacetyl etc?

 

[GnenieGone]

Cold crash, transfer, add potassium sorbate to put what yeast is left to sleep.

 

[thehaze]

What PianoMan said. But I am not a fan of killing yeast. Even if it results in a drier beer, I don't think that's a bad thing, especially for a beer, you can drink more than one at a time. Cheers!

 

[Vale71]

I've got a brew of a dark mild going and I'm noticing that the FG are going to be lower than expected, I.e. yeast will attenuate more than calculated. Reason for this is most likely my mash schedule. Anyway, I will let this one ride out but it got me thinking how I should act, if it's possible, to halt the fermentation as the expected/wanted FG is being reached. Is there a common practice for this, to "rescue " a fermentation that seems to attenuate more than you want?

Anything you do to kill yeast prematurely will:

- make the beer more unstable, as there will be fermentable sugars left (risk of secondary infection)
- make it taste overly sweet
- stop maturation processes that require active yeast

Besides the fact that the only 100% safe way to do that is sterile filtration followed either by aseptic filling or bottle pasteurization (way beyond the reach of even the most dedicated homebrewer) your beer will surely taste 10 times better if you just let it reach FG without messing around with it.

 

[schmurf]

Thanks people, yes I suspected the best thing was to let it finish the job it started. I was just curious if there was an acknowledged go to practice for occasions when it seems like yeast works harder than expected. I will RDWHAHB as usual.

 

[thehaze]

You have the option to stop/kill the yeast, but for me, that doesn't feel like a viable option. I am sure the beer will turn out well, provided it's not infected or something. I think you will be pleased with the result and if you are not, you can always brew another bacth and choose another yeast or another recipe, mash temp., etc. Cheers!

 

[Paulaner]

It's simple to halt fermentation, brewers do it all the time with German/Czech beers especially if you're spunding. For my forced fermentation test I typically reach 1.008 so depending on the beer I'm brewing I'll typically transfer to spunding at around 1.014-1.017 and the next day when I'm down to 1.010-1.013 I'll transfer the keg to my lagering fridge which I maintain at 28°F. Again I dial in the numbers for the beer style and what I'm shooting for in the finished product.

 

[Vale71]

You do realize you're not really stopping fermentation at all? You'll just make it go reaaaal slow, but as soon as you raise the temperature f.e. to serving temperature (I'm sure you don't drink your beer that cold!) it will speed up again. Really stopping fermentation in a safe and consistent manner takes a lot more effort.

 

[Paulaner]

You do realize you're not really stopping fermentation at all? You'll just make it go reaaaal slow, but as soon as you raise the temperature f.e. to serving temperature (I'm sure you don't drink your beer that cold!) it will speed up again. Really stopping fermentation in a safe and consistent manner takes a lot more effort.

You might want to do a little more research on your comment.