Topics Topics Help/Instructions Help Edit Profile Profile Member List Register  
Search Last 1 | 3 | 7 Days Search Search Tree View Tree View  

Visit The Brewery's sponsor!
Brews & Views Bulletin Board Service * Brews and Views Archive 2004 * January 9, 2004 * Fermenting cool, then warm < Previous Next >

  Thread Last Poster Posts Pages Last Post
  Start New Thread        

Author Message
 

chumley (63.227.172.30)
Posted on Tuesday, December 23, 2003 - 05:19 am:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

I am curious if anyone has ever tried on purpose much, starting out a fermentation fairly cool, then allowing the temperature to raise somewhat towards the end of primary fermentation in order to get a clean but well-attenuated beer? I am trying this right now. It would seem to me that the fruitier esters and higher fusel alcohols would be produced early, rather than later in the fermentation process? Therefore a slow and cool fermentation, raised at the end (after 50% apparent attenuation?) should produce a clean and dry beer. Any thoughts?

For the record, here's what I'm up to:

I have a slightly tweaked version of Bill Pierce's St. Chucks Porter recipe (tweaked in that I added an extra 1.5 lbs of 2-row to it, and got an OG of 1.060) that I brewed on October 27. I pitched a half gallon starter of Wyeast 1728 Scottish Ale, then put the glass carboy fermentor into the basement, expecting the constant 62°F temperature there that I have seen the past few months to remain somewhat constant.

Of course, the next day an "Alberta clipper" (to steal a phrase from another thread) moved in, and the temps outside dropped to -6°F. The temps in my basement also dropped to 54°F. The beer began fermenting, albeit slowly (Wyeast recommends 55-70°F for this yeast).

The temperature rose up to 56°F, and the porter fermentation continued very slowly. Finally, I couldn't stand it anymore, and took a gravity reading (it had slowed down considerably). It read 1.030 after 6 weeks in the primary. Its porter drinking season, so I decided to move it upstairs to the kitchen (where my wife doesn't want to see it). :)

Right now its back to bubbling once every 10 seconds. The fermometer reads 66°F. I plan to let it go until after the New Year, then take another gravity reading to see where I am at. If its above 1.020, B_E_A_N_O!!!!!
 

Fredrik (213.114.44.219)
Posted on Tuesday, December 23, 2003 - 08:26 am:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

I tried something similar on my last batch, first 5 days of primary was 55F, the last 3 days I stopped the cooling FAN and allowed to rise to 68F by itself. When racking to secondary it was the FG I wanted so I cooled it back to 55F for a week.

It seems that alot of the fuesels are produced during warm growth. But I think to some extent the actual esters may be produced later? So less fuesels produced early (due to lowering temp) seems to mean less esters?

I think the balance between fuesel/esters is determined in the later stages, when growth is slowing I think some fuesels are converted to esters. Using this logic rising temp in the end of primary should I think decrease the fuesel/ester ratio.

So having the initial temp fixed, I think not rising in the end may give less esters, but probably at the expense of more fuesels though the fuesel flavour tresholds seems lower in general.

/Fredrik
 

Doug Pescatore (141.232.1.10)
Posted on Tuesday, December 23, 2003 - 04:57 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Chumley,
I regularly play with the temperatures throughout the fermentation process. I ferment my ales and lagers at the low end of the yeast's spec's until the fermentation is slowed down (using the fredrik bubble counting method) and then start raising the temp gradually until it is at the top end. I don't have a problem with getting the fermentation stuck. I do this because I want to counter act the increase in temp due to fermentation in the initial stages and I move the temp up to make sure the fermentation gets done.

I have also used temp control to slow fermentation down enough to stop blow off.

-Doug
 

Jim Keaveney (205.188.208.75)
Posted on Tuesday, December 23, 2003 - 04:59 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

I am experimenting with a pale ale that i have brewed many times. I find that it improves with a bit of cold conditioning which i do not have time for on this batch. so i thought a cooler fermentation might help. i started it at 60F on sunday which is 3F below the stated range (WY 1335). i have not taken a reading but it seems to be putzing along very slowly (tho it started surprising quickly). after 36 hours i moved it up to 63F. i plan to increase the temp another 3-5F to help it fully attenuate. i plan to tap this beer when it is 3 weeks old and will compare it to a batch that has been cold conditioning for several months that was fermented at 68-70F.
 

chumley (199.92.192.126)
Posted on Tuesday, December 23, 2003 - 05:03 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

So if I understand what you are saying, Fredrik, a cool then warm fermentation may lead to more fusels but less esters? Hmmm. But since most of the fermentation occured "cool", there shouldn't be a lot of either present in the beer?

Guess the only way to find out will be to drink it when its done. Hopefully it will be clean and malty. But if it has that fusel solventy/alcohol bite to it, I suppose that will mean you are right.
 

Walt Fischer (24.221.196.114)
Posted on Tuesday, December 23, 2003 - 05:04 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Ill have to say i aggree with this...
Ive done this a few times, and i think it works great...
Bringing up the temp at the end doesnt seem to produce the fuesel/esters that fermenting warm the whole time would...
So id say its a pretty good way to reach a lower FG, even if just by a few points...

Walt
 

Hophead (167.4.1.38)
Posted on Tuesday, December 23, 2003 - 05:09 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Chumster, this is what I do with the majority of my ales, and it makes for a much cleaner ferment. You've hit the nail on the head; you will be pleasantly surprised. Fredrik won't like it, because it'll throw off the standard deviation of his magic bubble counter...
 

Fredrik (213.114.44.219)
Posted on Tuesday, December 23, 2003 - 10:20 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

> So if I understand what you are saying, Fredrik, a cool then warm fermentation may lead to more fusels but less esters? Hmmm. But since most of the fermentation occured "cool", there shouldn't be a lot of either present in the beer?

Perhaps I was foggy in my expressions. I think your original idea is close to the nail on the head like hophead said. What I meant to suggest is,

1) If the first 2/3 of or the primary contains most of the "growth", it should mean that most fuesels are produced during this part. So starting a bit cooler the first 2/3 should give less fuesels, and since by assumption fuesels are part of the ester precursors lowering this first temp also gives lower esters in the end.

2) In the last 1/3 of primary, assuming the growth is lower, according to my current interpretation of some ideas of Dr.Cone the Acetyl-CoA available for esters synthesis are increased, and that the cellsmembranes are now sloppy allowing fusels to brought back inside, suggesting that a significant part of the fuesels previously produced may now be converted into esters. This is probably promoted by increasing the temp of the later 1/3 part.

So I think a cool start, minimizes fuesels as well as limits esters, but the warm finish adjusts the fuesel/ester ratio balance down by converting fuesels to esters.

This is just 90% theoretical speculation as far as I am concerned, I've tried it once with success with one datapoint but I need more experience. If you try it please post the results!

/Fredrik
 

Fredrik (213.114.44.219)
Posted on Tuesday, December 23, 2003 - 10:34 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

> suggesting that a significant part of the fuesels previously produced may now be converted into esters.

Mmm or maybe put better, a significant part of the total ester production are produced here from conversion of previously produced fuesels.

/Fredrik
 

Jim Keaveney (64.12.96.42)
Posted on Wednesday, December 24, 2003 - 03:09 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

well, my experiment did not work out so well. after 48 hours it had only gone from 1.052 to 1.040 and no airlock activity tho it may have been going very slowly. i roused the yeast and moved it up to 67-68F where it wanted to be all along and it is going hard now.
 

Kevin Davis (67.233.12.198)
Posted on Wednesday, December 24, 2003 - 04:04 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

I have a batch started from a muntons lager kit with some extras, that is in my basement and maintaining about 60 deg. Should this be warm enough to complete the fermenting process? I have not checked the SG yet but it stopped bubbling last night. I used the dry yeast that came with the kit.
 

Jim Keaveney (205.188.208.75)
Posted on Wednesday, December 24, 2003 - 09:35 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

if it was a lager yeast, then you are fermenting a bit too warm. finishing should not be an issue

Add Your Message Here
Posting is currently disabled in this topic. Contact your discussion moderator for more information.