Diacetyl Rest if I'm Halting Fermentation

[awoitte]

If a beer hits target gravity and you don't want it to continue to ferment, is it possible to still do a diacetyl rest?

 

[Vale71]

The real question is: how do you inted to halt fermentation? Through pasteurization? Sterile filtration?
In any case if you do kill the yeast then no, dead yeast won't clean up diacetyl or any other by-product, you need live yeast for that.

 

[awoitte]

The real question is: how do you inted to halt fermentation? Through pasteurization? Sterile filtration?

Drop the temp to 32°F

 

[Vale71]

Then you're not halting fermentation at all, but you're certainly making it hard for the yeast to clean up any diacetyl or other by-product.

 

[awoitte]

Then you're not halting fermentation at all, but you're certainly making it hard for the yeast to clean up any diacetyl or other by-product.

What type of ale yeast ferments at 32°F?

 

[Vale71]

Cold does not kill yeast or any other microorganism, it only slows it down.
If your car is gently rolling along at a snail's pace instead of driving by at 100 MPH you still wouldn't say that your car has stopped, would you?

 

[awoitte]

Cold does not kill yeast or any other microorganism, it only slows it down.
If your car is gently rolling along at a snail's pace instead of driving by at 100 MPH you still wouldn't say that your car has stopped, would you?

My question wasn't about killing yeast, it was about stopping the conversion of sugars to alcohol while being able to rid any diacetyl produced during the fermentation process.

 

[Vale71]

And the answer is: to actually stop the conversion of sugars to alcohol you need to either remove or kill the yeast and doing that will prevent the yeast from doing everyting else, including diacetyl cleanup.

Just cooling the beer will only make everything happen much slower, including fermentation and diacetyl cleanup. In other words, you can't select what the yeast will do for you.

 

[RM-MN]

Target gravity is just an estimate of what the yeast will do. If you want the beer to end up at a certain gravity you create the conditions for that that to happen. Once you pitch the yeast they are in control, not you and you just let them do their thing.

Don't get hung up on hitting a specific "target gravity". Make good beer and the final gravity will be whatever the yeast decide and the beer will still be good. Trying to stop it at a certain number will cause you plenty of problems without solving any.

 

[Yooper]

My question wasn't about killing yeast, it was about stopping the conversion of sugars to alcohol while being able to rid any diacetyl produced during the fermentation process.

Yeast don't selectively do what you want them to do- they ferment, and as fermentation nears completion (that is, they have fewer fermentable sugars to consume), they will start to digest other things (including their own waste products).
They will not consume much diacetyl or other things until their preferred food sources are depleted.

I can't think of any reason to try to halt the process, unless you are afraid that the beer will finish too dry?

 

[Die_Beerery]

I can't think of any reason to try to halt the process, unless you are afraid that the beer will finish too dry?

In order to hit proper body and mouthfeel in German lagers, there needs to be differing amounts of residual extract left, and thats based of the beer style being produced. So you use a very fermentable mash schedule, and from there you have some options. A less attentative yeast strain is easiest (but only if you can find one that suits the beer style), or halting fermentation. I do the latter, and the levels are referenced here:

[Narziss, 2005] lists ranges for the differences between finished beer attenuation and limit of attenuation for some German beer types:

• Helles : 2 - 4%
• Export : 0.5 - 2 %
• Pilsner : 0.5 - 4 %
• Bock, Dunkel : up to 6 %

This is in no way shape or form the same as mashing higher, and having residual dextrins. Fermantables are sweet, dextrins are flabby and muddy. So, I have no idea of the OP's intentions, but those are mine.

 

[Jag75]

What about sulfite and sorbate ? I use these in mead. I know it doesnt kill the yeast but it does keep it from growing. I'm not sure how long it would take or even if it would cause a bottle bomb .

 

[Jag75]

In order to hit proper body and mouthfeel in German lagers, there needs to be differing amounts of residual extract left, and thats based of the beer style being produced. So you use a very fermentable mash schedule, and from there you have some options. A less attentative yeast strain is easiest (but only if you can find one that suits the beer style), or halting fermentation. I do the latter, and the levels are referenced here:

[Narziss, 2005] lists ranges for the differences between finished beer attenuation and limit of attenuation for some German beer types:

• Helles : 2 - 4%
• Export : 0.5 - 2 %
• Pilsner : 0.5 - 4 %
• Bock, Dunkel : up to 6 %

This is in no way shape or form the same as mashing higher, and having residual dextrins. Fermantables are sweet, dextrins are flabby and muddy. So, I have no idea of the OP's intentions, but those are mine.

Are those % you posted unfermented ? So if your expecting a 5.4 ABV Export you halt fermentation to 5.0 leaving the .4 ? If so how are you doing that and it seem like it be really difficult. Maybe that's why you have a between this and that idk. You do this kegging only I take it.

 

[Die_Beerery]

Are those % you posted unfermented ? So if your expecting a 5.4 ABV Export you halt fermentation to 5.0 leaving the .4 ? If so how are you doing that and it seem like it be really difficult. Maybe that's why you have a between this and that idk. You do this kegging only I take it.

Its residual extract remaining. So for demonstration.
If you did a fast ferment test, and that fermented to 1.007-8 (most all german beers target this, if I use a broad brush stroke).
Then you want fermentation to stop higher based on the beer style, from 1.009 to 1.014 (again using a very broad brush).

That allows for fermentable sugar (sweet, and body enchancing) to properly balance the beer based on the style.

 

[Jag75]

Its residual extract remaining. So for demonstration.
If you did a fast ferment test, and that fermented to 1.007-8 (most all german beers target this, if I use a broad brush stroke).
Then you want fermentation to stop higher based on the beer style, from 1.009 to 1.014 (again using a very broad brush).

Ok , so how do you go about stopping a beer that's predicting 1.007-8 to actually stopping at 9-14?

 

[Die_Beerery]

Ok , so how do you go about stopping a beer that's predicting 1.007-8 to actually stopping at 9-14?

Just remember these are professional fermentation techniques. So homebrewers can either sterile filter or try and crash cool and hope you had a healthy fermentation, with happy yeast, that didn't produce too many off flavors or bi-products.

 

[Albionwood]

Short answer: No.

Trying to halt fermentation is generally a mistake. It's very difficult to do, and it creates more problems than it solves. You're better off letting this one run its course, see how the beer turns out, and then adjust your recipe and/or technique to get a different beer next time.

Cold-crashing is basically forcing a stall. At the homebrew level it's nearly impossible to sterile filter, so unless you pasteurize, that yeast is still alive and waiting its chance. If you keg it, you might just get an overcarbonated beer; but if you bottle it... well, cleaning up a sticky mess full of glass shards puts you in the company of a lot of old-school homebrewers.

 

[dmtaylor]

What about sulfite and sorbate ? I use these in mead. I know it doesnt kill the yeast but it does keep it from growing. I'm not sure how long it would take or even if it would cause a bottle bomb .

I have used sorbate before in a near-finished beer... specifically in a bottle-conditioned IPA. The result in the short term was a flat uncarbonated diacetyl-laden beer. After several months, finally I got carbonation and the diacetyl went away. But it took a long time and I don't know that the beer was any better for having done it.