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Old 03-15-2011, 03:54 PM   #31
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I'm still doing ALL of my beers with open primary like this. Given that I'm fermenting only 5 or so gallons at a time, that puts my vessel ratio of diameter/width to depth at about 1:1, which is ideal for open fermentation. Some of the professional breweries in Europe likely use vessels that are much shallower. The research that I've done suggests that these proportions of the vessel are key to getting the improved flavor contributions of esthers and phenols since there is much more surface area for the yeast to colonize and do their work.

It seems like a lot of people tend to correlate this method to wild/sour fermentations or even just refuse to be open to the idea that there could be some real benefits here. This is really not that risky!

One thing to be clear on is that open fermentation is a technique strictly for primary fermentation. Beers that require some conditioning are still transferred to closed secondary containers in this concept. No one is advocating exposing beer directly to oxygen or other potentially quality degrading elements. Brewers who use this method understand that active fermentation produces an incredible amount of CO2, enough to protect the beer from harmful elements as effectively as a closed vessel does. However, this stands true only as long as there is active fermentation present. Once the yeast have fully attenuated and the krausen drops, the beer is officially vulnerable to oxidization, contamination, etc. I always rack just before this phase, when there is still yeast on top and apparent attenuation is maybe around 90% complete. I let it finish out in a carboy before bottling. I have NEVER had any contamination with this method, nor have I picked up any off-flavors. All things considered, the quality of the end product has been outstanding.

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Old 03-15-2011, 04:16 PM   #32
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Another point to keep in mind...

Bacteria and wild yeast are not Bugs!

They do not have legs and they cannot simply climb into the fermenter. The fact is that anywhere there is anything, there are microorganisms present. Even your hand sanitizers and kitchen cleaners can only claim to disinfect up to 99%. With exception of high-tech laboratories, it is impossible for a brewer to create a 100% sterile environment. And as was noted about acetobacter, pretty much any "contaminating" organism that can potentially spoil the beer is already present in the beer or will result in you putting some material into the fermenter.

Fermentation itself is sort of a form of natural selection. There is competition for food resources and as a result, only the fittest organisms will survive. Inoculation with healthy yeast starters, as opposed to wild fermentation, ensures that only the selected yeast strain will dominate and grow. Without adequate food and conditions, other organisms simply are not able to grow to a point where they are perceptible in the end-product. But they are there alright!

Even in sour beer production, certain measures are taken to provide food and habitat for the "wild" organisms to reproduce. It is not a completely hands-off technique of brewing. You have to make an effort to make a good sour beer.

There are many factors to good fermentation. The ph, amount of alcohol, dissolved oxygen, tannins, astringency and preservative oils from herbs (hops), and fermentability of the wort. When you take in the complete picture of fermentation as both chemical AND biological processes, the choice of open vs. closed vessel is not really a game changer. Every brewer I know has had batches at one time or another, and I'm the only one I know who uses open fermentation. Educating yourself on brewing, using best practices, and eliminating deficiencies in your system is the only sure way to avoid bad results.

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Old 03-15-2011, 05:29 PM   #33
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If the surface area to depth ratio is the important part, has anyone tried using something like a rubbermaid storage bin as a fermenter? You could probably one that holds 5 gals that's as thin as 8" deep if you wanted to go to the extreme end.

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Old 03-16-2011, 03:41 PM   #34
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Originally Posted by aaronkaz View Post
the start of active fermentation - mostly just foam but looks really neat, almost like an aerial view of mountains. The darker stuff is trub that can be skimmed off....



peak primary ferment - the krausen is about 2 inches thick


close of up krausen


near the end of primary - krausen is much thinner, but is a thick cake floating on top still
what kind of beer is this? looks like a nice, healthy fermentation. mine never developed a krausen at all but the hydro readings have been trending in the right direction so i'm not worried. the hydrometer samples have tasted good so if it get contaminated with something it has not reared it's ugly head yet.
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Old 03-16-2011, 03:45 PM   #35
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Originally Posted by aaronkaz View Post
I'm still doing ALL of my beers with open primary like this. Given that I'm fermenting only 5 or so gallons at a time, that puts my vessel ratio of diameter/width to depth at about 1:1, which is ideal for open fermentation. Some of the professional breweries in Europe likely use vessels that are much shallower. The research that I've done suggests that these proportions of the vessel are key to getting the improved flavor contributions of esthers and phenols since there is much more surface area for the yeast to colonize and do their work.

It seems like a lot of people tend to correlate this method to wild/sour fermentations or even just refuse to be open to the idea that there could be some real benefits here. This is really not that risky!

One thing to be clear on is that open fermentation is a technique strictly for primary fermentation. Beers that require some conditioning are still transferred to closed secondary containers in this concept. No one is advocating exposing beer directly to oxygen or other potentially quality degrading elements. Brewers who use this method understand that active fermentation produces an incredible amount of CO2, enough to protect the beer from harmful elements as effectively as a closed vessel does. However, this stands true only as long as there is active fermentation present. Once the yeast have fully attenuated and the krausen drops, the beer is officially vulnerable to oxidization, contamination, etc. I always rack just before this phase, when there is still yeast on top and apparent attenuation is maybe around 90% complete. I let it finish out in a carboy before bottling. I have NEVER had any contamination with this method, nor have I picked up any off-flavors. All things considered, the quality of the end product has been outstanding.
very well put!
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Old 03-17-2011, 03:05 AM   #36
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I was thinking of racking at the tail end of vigorous part of the fermentation to get the beer off the trub, but with enough sugars to blank the beer in the secondary.

Transferring a large amount of yeast at this point doesn't seem to be a big thing since currently I use the primary only.


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In full activity, I do believe that yeast can protect itself from most of the problems brewers worry about. I always rack to secondary carboy just before the krausen drops - by this time, the beer has already reached (or is very close) to the terminal gravity and any later, will start to becom susceptible to contamination.
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Old 03-17-2011, 02:08 PM   #37
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Originally Posted by gr8shandini View Post
If the surface area to depth ratio is the important part, has anyone tried using something like a rubbermaid storage bin as a fermenter? You could probably one that holds 5 gals that's as thin as 8" deep if you wanted to go to the extreme end.
That's a really interesting idea! I've been wondering what else I can use if I ever upgrade to a 10gal system in the future. My only concern is that the molded handles and such would be harder to clean. You could cut that whole top rim off though and just be careful with cleaning as to minimize scratches in the surface.
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Old 03-17-2011, 03:45 PM   #38
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what kind of beer is this? looks like a nice, healthy fermentation. mine never developed a krausen at all but the hydro readings have been trending in the right direction so i'm not worried. the hydrometer samples have tasted good so if it get contaminated with something it has not reared it's ugly head yet.
I think the beer in the photo was an IPA (o.g 1.060) with WLP001 Cal as the yeast. I've been top cropping yeast with this setup and the repitchings have made super healthy, vigorous fermentations since there's so much viability. I heard on a Jamil show that he didn't recommend 001 as a top-cropping strain, but as you can see in the photo, in an open vessel it works pretty well for this purpose.

There's nothing to worry about, but I would try to track down why your batch didn't develop a krausen. I really depend on it as a strong co2 buffer and as the source for harvesting yeast for the next generation. I well-aerate my wort before pitching as well. Its really amazing how different yeast behaves in different vessels.

I have noticed though that krausens are smaller in lower gravity wort. I realized that I was overpitching in lower-og batches which may mean that cell reproduction is reduced, meaning a smaller krausen.

Its also important to be sure that you don't rack to secondary too soon. You can get a lot of diacetyl by racking midway in primary ferment.
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Old 03-17-2011, 03:58 PM   #39
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Quote:
Originally Posted by aaronkaz View Post
Another point to keep in mind...

Bacteria and wild yeast are not Bugs!

They do not have legs and they cannot simply climb into the fermenter. The fact is that anywhere there is anything, there are microorganisms present. Even your hand sanitizers and kitchen cleaners can only claim to disinfect up to 99%. With exception of high-tech laboratories, it is impossible for a brewer to create a 100% sterile environment. And as was noted about acetobacter, pretty much any "contaminating" organism that can potentially spoil the beer is already present in the beer or will result in you putting some material into the fermenter.

Fermentation itself is sort of a form of natural selection. There is competition for food resources and as a result, only the fittest organisms will survive. Inoculation with healthy yeast starters, as opposed to wild fermentation, ensures that only the selected yeast strain will dominate and grow. Without adequate food and conditions, other organisms simply are not able to grow to a point where they are perceptible in the end-product. But they are there alright!

Even in sour beer production, certain measures are taken to provide food and habitat for the "wild" organisms to reproduce. It is not a completely hands-off technique of brewing. You have to make an effort to make a good sour beer.

There are many factors to good fermentation. The ph, amount of alcohol, dissolved oxygen, tannins, astringency and preservative oils from herbs (hops), and fermentability of the wort. When you take in the complete picture of fermentation as both chemical AND biological processes, the choice of open vs. closed vessel is not really a game changer. Every brewer I know has had batches at one time or another, and I'm the only one I know who uses open fermentation. Educating yourself on brewing, using best practices, and eliminating deficiencies in your system is the only sure way to avoid bad results.

Metaphoric bugs.
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Old 03-17-2011, 08:34 PM   #40
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Quote:
Originally Posted by aaronkaz View Post
I think the beer in the photo was an IPA (o.g 1.060) with WLP001 Cal as the yeast. I've been top cropping yeast with this setup and the repitchings have made super healthy, vigorous fermentations since there's so much viability. I heard on a Jamil show that he didn't recommend 001 as a top-cropping strain, but as you can see in the photo, in an open vessel it works pretty well for this purpose.

There's nothing to worry about, but I would try to track down why your batch didn't develop a krausen. I really depend on it as a strong co2 buffer and as the source for harvesting yeast for the next generation. I well-aerate my wort before pitching as well. Its really amazing how different yeast behaves in different vessels.

I have noticed though that krausens are smaller in lower gravity wort. I realized that I was overpitching in lower-og batches which may mean that cell reproduction is reduced, meaning a smaller krausen.

Its also important to be sure that you don't rack to secondary too soon. You can get a lot of diacetyl by racking midway in primary ferment.

my hydro readings stayed at 1.020 for three days so i pitched another wyeast forbidden fruit and that seemed to bring it back to life by the next day. i've never had a fermentation like this one so i'll be interested to see what the end result is like.

i don't use a secondary at all, just 2-3 weeks in the primary then i bottle condition for 4-6 weeks.
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