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Old 01-27-2013, 12:09 AM   #1
n8huntsman
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Default Another acetaldehyde question

I brewed my first extract batch, a nut brown, using Nottingham yeast. Fermented around 70°. I fermented the 5 gallon bactch in a 15 gallon conical. I LHBS said when the airlock bubbles slow to a bubble per minute, transfer to secondary for another week, keg, chill, carb, shake, settle for a day, then enjoy. I ended up not getting an airtight seal on the conical so I never saw bubbles, but I could see krausen foam forming on top and it was a few degrees warmer than the ambient temperature according to the stick on fermometer so I was fairly certain it was fermenting. The krausen subsided after about 5 days. After 7 days, instead of transfering to a secondary, since I'm using a conical, I dumped the trub from the bottom valve. I then let it sit for another week. SG seemed to be done moving so I transfered to the keg. I did taste it at this time and it tasted and smelled like green apples (acetaldehyde) but not knowing what to expect at that point, I continued on. Chilled the keg, force carbed it, let it settle for a day and of course the taste is still there. It's pretty bad to me, but my friends dont think it's too bad, the 5 gallons are almost gone!
So now I'm brewing a california common "steam beer" with saflager s-23. It fermented the first 3 days around 63° (ambient was 58°) and is now sitting around 68° which is also now the ambient temp. This time I'm going to give it at least 3 weeks and leave it on the trub the whole time since I now know not to worry about yeast autolysis over that short of a period. It's been two weeks now, and I popped the top on the fermenter to take a sneak peak and whiff. Again, I can smell the green apples. I'm going to let it sit for another week at least before I keg but I'm curious if there is anything else I can do to prevent the acetaldehyde? Can I gently stir the trub to rouse the yeast so they can turn it into ethanol?

Thanks and sorry for the long first post.


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Old 01-27-2013, 12:19 AM   #2
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Just let it sit till the yeast metabolizes it. I recently had acetaldehyde rear its head with a lager I brewed. Took an extra 12 days on the cake but it completely went away. Keep sampling and don't rack till it's gone.


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Old 01-27-2013, 11:00 AM   #3
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You were given some bad instructions on brewing schedules. Many kits have this same weakness in their instructions. When the vigorous phase of fermentation is over (called attenuation phase), a second phase begins (called conditioning) that is just as important as attenuation phase. It is where the by-products (like acetaldehyde) are converted. Conditioning is the longer duration phase of fermentation.

If temperatures are too high in the attenuation phase, then conditioning will take longer than normal. S-23 http://www.fermentis.com/wp-content/...02/SFG_S23.pdf
Your temps are a little high for it. So longer time is indicated. I have been using room temp yeasts to simplify.

Here is a link to one of the best brewing books around. The latest edition is available to buy, and the previous edition is here on line and free to all.

http://www.howtobrew.com/

A good schedule is to leave it in primary for at least 2-3 weeks on normal gravity beers and longer for high gravity. Then about 3-5 more weeks to great taste.

A fair expectation is to have great beer about 7 weeks after pitching the yeast. Kegging is somewhat faster. My first few batches were heavy green apples even at 7 weeks, and then they became great beers a few weeks later. So just brew some more and wait it out.
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Old 01-27-2013, 11:19 AM   #4
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Iīm sorry jethro55 but I donīt agree a bit. If you perform a clean good fermentation with temp controll and pitching the rigth amount of yeast times are shorter. Asumming and standard ABV beer, it takes about 5 days to fully ferment, 48 hs on the yeast cake itīs enough time for the yeast to clean after themselves, I donīt secondar very often, but a week in secondaty or an extra week in primary do the trick. After that I bottle. If you messed up somewhere in the proccess longer conditioning times may be requiered

n8huntsman thatīs a lot of headspace you got there.
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Old 01-27-2013, 11:35 AM   #5
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Quote:
Originally Posted by Obliviousbrew View Post
Iīm sorry jethro55 but I donīt agree a bit. If you perform a clean good fermentation with temp control and pitching the right amount of yeast times are shorter. Assumming and standard ABV beer, it takes about 5 days to fully ferment, 48 hrs on the yeast cake itīs enough time for the yeast to clean after themselves, I donīt secondary very often, but a week in secondary or an extra week in primary do the trick. After that I bottle. If you messed up somewhere in the process longer conditioning times may be required

n8huntsman thatīs a lot of headspace you got there.
OK, I'm listening. But experiencing a different timing...

Here are some comments from last month on the time from pitching to drinking:
http://www.homebrewtalk.com/f39/time...inking-378767/

And some guidance from Palmer's book.
http://www.howtobrew.com/section1/chapter8-2.html
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Old 01-27-2013, 11:43 AM   #6
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thatīs the thing with homebrewing jethro55, some rules of thumb like 2 weeks primary 3 weeks secondary are not always valid but they can be a good advice for someone starting. Grain to glass can be shorter, actually commercial breweries turn their beer pretty fast. Iīm not saying that you are wrong just that those rules donīt always apply. Iīm turning beers fast but I have very clear that yeast doesnīt work on my schedule, I just let my taste buds decide.
Good thing about this hobby is the bunch of different opinions around, none is more valid than the other. Palmers book is great but a little dated.
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Old 01-27-2013, 03:07 PM   #7
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N8huntsman- I suspect you are getting acetaldehyde because of too much oxygen during the fermentation process. Ideally, fermentation takes place in an anaerobic (oxygen poor) environment. The yeast metabolize the sugars to alcohol and all is good. Sounds from your post like you had a bad seal on your fermenter ( no bubbles in the air lock ) and you do have a lot of headspace in that photo, too. In the presence of oxygen, the fermentation products will continue past alcohol to acetaldehyde and eventually to acetic acid (vinegar) with enough time and oxygen. Suggest limiting the oxygen exposure in you fermenter by making sure all your seals are tight and fill that thing up to reduce the headspace.
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Old 01-27-2013, 04:28 PM   #8
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On a side note..I have used s-23 at those temps and get a very clean beer, contrary to what the manufacturer puts out.
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Old 01-27-2013, 05:35 PM   #9
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He did say that it's a 15 gallon fermenter he's doing 5 gallon batches in. I'd put that monstrosity away till I could put 10 gallons of wort in it. Then get a 6.5 gallon ale pail to ferment those 5 gallon batches in. Way to much head space in that 15 gallon one.
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Old 02-01-2013, 02:59 AM   #10
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I'm thinking about getting a good seal, then purging it with co2 prior to placing the air lock for my next fermentation. i can take out the thermometer, since it's above the wort anyways, add a valve, purge with co2, and close the valve. I'm also going to get one of those co2 aerating stones for my next batch.

As far as this batch goes, I pulled a sample last sat. (two weeks into fermentation) It was at 1.02 . I pulled another today and it's still 1.02. Sat. will be 3 weeks. Is it too late to try to rouse the yeast with some gentle stirring of the yeast cake/trub?


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