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 Post subject: Comments on the Fermtor BS show
PostPosted: Mon Oct 05, 2009 7:52 am 
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Joined: Mon May 22, 2006 11:32 am
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Location: Pepperell, MA
I just listed to the fermentor BS show and would like to loose a few comments.

I don’t buy the argument that a corny keg is not suitable for a good primary fermentation because it is tall and slim. To my knowledge, yeast flavor profile has more to do with fermentor height and convection currents than the actual height/diameter ratio of the fermentor. And the few additional inches that the wort will stand higher in a corny keg than in a carboy shouldn’t make a big difference. There should also be similar wort current patterns in a corny keg compared to a carboy. And since it is round there are no dead corners either. You mentioned that none of you compared fermenting in a corny to fermenting in a carboy, for example, and I haven’t either. But talking about it leads to speculation which just creates myths that perpetuate from there.

Another thing that I believe is a myth is the idea that the water column in the airlock makes a difference to the yeast by means of exerting pressure. If you do the math, a 2 cm water column exerts a pressure of 0.002 bar which is 0.03 psi. This equals an elevation difference of about 25m or 70ft. If such pressure differences would matter Denver brewers should make dramatically different beers compared to L.A. brewers.

If there is a difference between open and air-locked fermentation, it must be something else. The presence of oxygen in the head space for example would be a better explanation.

Aside from that it was a good show. Keep the good stuff coming.

Kai

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 Post subject: Re: Comments on the Fermtor BS show
PostPosted: Mon Oct 05, 2009 8:15 am 
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My biggest complaint about 5 gallon kegs is that they are just too small. How can I end up with 5 gallons of finished beer, unless I brew concentrated beer and add water at package time?

Plus, my arms are too big to fit in the keg more than a tiny bit so it is not any easier to clean.

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 Post subject: Re: Comments on the Fermtor BS show
PostPosted: Mon Oct 05, 2009 8:50 am 
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I'm not saying that they are ideal vessels for brewing 5 gal batches. I was just pointing out that there was a lot of unsupported speculation why they would not work. I do plan to use them in the future when I want to evaluate the effect of pressurized fermentation on the flavor proile. But then I'll be using them b/c I wouldn't have anything else to do that with.

I have seen posts by a number of brewers who use them for primary fermentation. The closed design makes transfer to another keg for secondary or serving pretty easy. You'll have to know how much trub to anticipate and cut the dip tube. Yeast harvesting or the idea of taking the trub out of the beer through the dip tube and ball/pin lock valve would be a pain or even impossible, though.

As for reaching into them, I tend to think the same when I reach in and clean them: "If I were to work out and get stronger arms, I might not be able to clean my kegs anymore ;) ".

Cheers,
Kai

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 Post subject: Re: Comments on the Fermtor BS show
PostPosted: Mon Oct 05, 2009 3:01 pm 
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Joined: Fri Jan 02, 2009 3:29 pm
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Location: Central Coast, CA
I heard this, and decided to run an experiment. I made 11 gallons of California Common, and made a starter(2 step starter, think I pitched correctly).

(1) I filled a 5 gallon glass carboy with 3.5 gallons of wirt, and added 2 liters of starter.

(2) I filled a 5 gallon corney with 3.5 gallons of wort, and added 2 liters of started.

(3) I took the rest into a 5 gallon carboy, added 2.5 liters of starter, some oak, and placed in a party bucket with an old t-shirt and a fan. my fermentation chamber isn't that big. This was my "see what happens" beer. It should be ignored for the purposes of the experiment.


Each should have similar head space. I routed the blowoff from the corney to the carboy cap. They effectively used the same airlock, so pressure should have been similar during fermentation. I used the 2 minute shake method for aeration for both. They were both placed them in my converted chest freezer fermentation chamber set at 61 degrees for the first week, then 63 since.


I took hydrometer samples at 1 week (SG was 1.056):
(1) 1.017
(2) 1.021

I was surprised that the Corney was a few points behind. As far as taste, the (2) sample was a little sweeter then the (1) sample, but had the same aromatic and bitter qualities. My palate isn't as refined as others, especially with flat beer, but that's why I taste it. Hopefully it will get better with more experience. I look forward to the finished beer.

While granted, this is a n=1 sampling, I'll continue to look at this for at least a few more brews until I fully commit to corneys as a primary fermentation vessel.

I'll update you with more as I take another sample shortly.

The Fool

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 Post subject: Re: Comments on the Fermtor BS show
PostPosted: Mon Oct 05, 2009 11:12 pm 
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For transfers under CO2 it is still possible, though dangerous, with carboys. That is one of the things I like about the better bottles. I figure I can use a moderate amount of pressure with a lot less danger than a glass carboy.

While I haven't done much with fermenting in kegs, I have compared other vessels and found that minor changes in shape do seem to result in detectable results. However, that doesn't mean different = bad. Just different. A brewer should be able to either ignore or overcome those differences with other adjustments, such as strain selection, pitching rate, O2, temp, etc.

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Jamil Zainasheff
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 Post subject: Re: Comments on the Fermtor BS show
PostPosted: Tue Oct 06, 2009 5:48 am 
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bikefoolery wrote:
I was surprised that the Corney was a few points behind. As far as taste, the (2) sample was a little sweeter then the (1) sample, but had the same aromatic and bitter qualities. My palate isn't as refined as others, especially with flat beer, but that's why I taste it. Hopefully it will get better with more experience. I look forward to the finished beer.


Thanks for running that experiment.

Could it be that the greather bottom area of the carboy and thus greater yeast contact area caused the fermentation in there to move along faster than in the carboy? I'm curious as to where both beers finish.

Jamil,

Because of the inherent danger, I don't like advocating the transfer from a carboy though CO2 pressure. While the risk of something happen might be low, if properly monitored, the consequences, if something happens, can be fatal.

Kai

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 Post subject: Re: Comments on the Fermtor BS show
PostPosted: Tue Oct 06, 2009 8:59 am 
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I have used glass carboys, Better Bottles, Corney kegs and buckets. Carboys and buckets are very close to the same diameter so they take up about the same room in my chest freezer. For years I turned my nose up at them so I only recently started using buckets (about 10 batches) and I am sold on them. Albeit if I could afford conicals this argument would be pointless :D

I like buckets because:

1. they are marked with quantity
2. simple gravity transfer to keg
3. cheap to replace
4. easier to handle than carboys
5. do not clog during transfer like kegs
6. pressure transfer from carboy is a pain and unsafe
7. I can add excess wort to accomodate for trub loses
8. I can hose them out in the shower with a hand held sprayer (have not tried bathing in yeast yet) :roll:
9. glass carboys break (been there, done that)
10. Better Bottles are not keen on boiling water for sanitizing, they tend to melt


I am sure everyone has their own reasons for what they use, this is just my peronal choice.


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 Post subject: Re: Comments on the Fermtor BS show
PostPosted: Tue Oct 06, 2009 9:17 pm 
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Buckets can be an excellent choice also. I don't think any of these is really a "bad" choice. Just different pluses and minuses.

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I hope my post helped in some way. If not, please feel free to contact me.

Jamil Zainasheff
http://www.mrmalty.com

"The yeast is strong within you." K. Zainasheff


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