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maltMonkey

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Has anyone ever done an open fermented ale? I was just reading an article about how Samuel Smith's (my favorite brewery) does all open fermentation with a Yorkshire Square. Is there any way to replicate this system/method at home?
 

Evan!

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The only reason to do an open fermentation at home, really, is to purposely introduce wild bacteria into your wort to create sour beers (lambic, gueuze, etc.). Otherwise, you'll not really be affecting your beer very much. The unique characteristics that a yorkshire square lend to a beer don't really come from the fact that it's an open fermentation as much as from the fact that they use stone/slate to make it. If you wanna try that out, more power to ya.
 

landhoney

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maltMonkey said:
Has anyone ever done an open fermented ale? I was just reading an article about how Samuel Smith's (my favorite brewery) does all open fermentation with a Yorkshire Square. Is there any way to replicate this system/method at home?
Supposedly open fermentation allows for a stronger yeast character in the beer. In the same way breweries use pressurized fermentation vessels to inhibit yeast character, the opposite allows for more yeast derived flavors. I know people(including myself) have tried this with Belgian(non-sour) styles by removing the liquid in the airlock once 'high-krausen' has started and there is a fairly constant flow of CO2 out of the fermenter. Whether this makes a big difference or not..????

I think it is that the shape of the vessel that makes a larger impact. Shallow and wide vessels allow for less pressure because there's less weight/pressure on top of the yeast. The link says, " Yorkshire Square vessel is a two-story system consisting of a shallow chamber approximately "

Maybe try fermenting 5 gallons in 3 different carboys without liquid in the airlocks once high-krausen has started? No pressure + shallow liquid level?
 

Ryanh1801

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Yep, just did on my last trippel, but only because I had some crazy fermentation and it keep trying to blow the lid off.

 

aekdbbop

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From what I have heard, the co2 will protect your beer fairly well from infections. I have just used al. foil over the top of my carboy before without using an airlock. Kinda the same thing, but less surface area.

If i were to do something with more surface area, I would cover it until it started to ferment, then take off the cover and let it go, then when things settle down, put the lid back on.
 

TexLaw

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Keep in mind that the breweries that practice open fermentation ferment a whole lot of beer in the same place, using the same strain. Chances are good that there aren't many other microbes living in that area, so contamination isn't much of an issue.

The homebrewers that take the lid off after active fermentation begins are well protected by a few things. First, the yeast is up and running at full speed, so shame on anything else that tries to get a foothold in that fermenter. By the time the yeast is through with its party, the pH of the beer is low enough and the alcohol is high enough to keep any stray microbe from doing much else. Also, the CO2 generated literally blows away much of anything that would otherwise land in the fermenter.

It could be a very different story if a homebrewer were to just pour wort into an open fermenter, pitch some yeast, and let nature take its course. I bet Landhoney can talk all about that! :)


TL
 

EinGutesBier

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I'm sure there's a million and one variables, but I wonder what the typical attenuation/ABV of your average wild yeast would be? Or would it be foolish to depend entirely on that and hedge your bets with a packet or two of cheapo dry yeast?
 

landhoney

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EinGutesBier said:
I'm sure there's a million and one variables, but I wonder what the typical attenuation/ABV of your average wild yeast would be? Or would it be foolish to depend entirely on that and hedge your bets with a packet or two of cheapo dry yeast?
I don't think he wants an "all wild yeast" beer. But FYI, mine went from 1.060 down to 1.002 by using 100% wild yeast that were floating around and found their way into my beer. It was foolish, but I tried it anyway, and it turned out very well. :D
 

EinGutesBier

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Do you mind if I ask what location you're at? I'm sure there's gotta be a couple tasty yeasts here in the continental US. : / Also, any other tips you have would be appreciated. I'm debating doing an open fermentation since it's still in the swing of winter here in WI and there shouldn't be too many unwanted organisms floating around. How long do you expose the wort?

Almost forgot. Congrats on your good attenuation. : D How long did that take? Sorry about all the questions - just curious.
 

landhoney

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EinGutesBier said:
Do you mind if I ask what location you're at? I'm sure there's gotta be a couple tasty yeasts here in the continental US. : / Also, any other tips you have would be appreciated. I'm debating doing an open fermentation since it's still in the swing of winter here in WI and there shouldn't be too many unwanted organisms floating around. How long do you expose the wort? Almost forgot. Congrats on your good attenuation. : D How long did that take? Sorry about all the questions - just curious.
https://www.homebrewtalk.com/showthread.php?t=43888

It took a little over two months, that thread contains all the info. Also, mine was ambient or spontaneously fermented. Open fermentation is different from what I did, mine was only open for 2-3 days or so to get the wild yeast in there, and then fermented with an airlock. But, trying open fermentation while using a cultivated strain is a cool idea. Unless you're saying you want an all wild yeast beer.
 

EinGutesBier

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I have a pretty good idea of what an all wild yeast beer would taste like. The traditional, strong "fermented, yeasty" flavor and aroma would be present. How would it work together with a cultivated yeast strain, I wonder...
 

landhoney

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EinGutesBier said:
I have a pretty good idea of what an all wild yeast beer would taste like. The traditional, strong "fermented, yeasty" flavor and aroma would be present. How would it work together with a cultivated yeast strain, I wonder...
How would you have "a pretty good idea" what it would taste like?
And what would be a commerical beer or beer style that has the " traditional, strong "fermented, yeasty" flavor and aroma" you expect a wild fermented beer would have?

Also, any beer I've ever heard of made this way(Lambic's, other homebrewers, my own) is sour. You might say sourness is its stongest characteristic.
 

pjj2ba

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I've been to two brew pubs that use open fermentors. In both cases the fermentors were in their own "clean" room. If I had a spare room where I could hose down all of the surfaces, I see no problem with open fermentations. This was the standard procedure for most of beer brewing history. My concern with wild fermentaions would be contamination with acetobacter, giving you malt vinegar. I think though as long as it gets off to a quick start you're fine. It don't know that it would be a beer I'd want to age though as given time, any contaminants could take off then.
 

JLem

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Chances are good that there aren't many other microbes living in that area, so contamination isn't much of an issue.
I have to argue with this point. Chances are there are LOTS of microbes living in that area - you can't go anywhere without there being microbes. Whatever the reason they don't get infections (or maybe they do?) it is not because there are no microbes there.
 

radtek

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I've experimented with open (bucket lid not snapped down) fermentation. At least 20 if not more batches. I think it produces a great beer. However I've had more instances of infection by doing so. I've since reverted to closed fermenters and the beer is just as good.

I suspect air flow still gets in under the loose lids carrying dust or some fomite introducing the bad bacteria.
 

ke

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Supposedly open fermentation allows for a stronger yeast character in the beer. In the same way breweries use pressurized fermentation vessels to inhibit yeast character, the opposite
In this post you referred to brewing under pressure making for a cleaner tasting yeast profile. I just brewed a west coast red based on this recipe http://beerdujour.com/Recipes/Jamil/JamilsAmericanAmberAle.htm with non-recommended safale so4 yeast . I was interested in getting a cleaner yeast taste closer to the recommended wyeast 1056 american ale or fermentis so5 .

Are you aware of the kind of pressure levels which create cleaner profiles?

Anything more than blowoff tubes going to the bottom of a carboy ( about 1 psi ) would be awkward to facillitate, plus now a few days have elapsed and I'm already at 2/3 attentuation so this is really is academic question. Even fermenting with pressure relief caps as in http://www.zimbio.com/Homebrewing/articles/72/Review+Easy+Bottle+Brew would be awkward, although fermenting in corney kegs equipped with pressure relief valves protected from clogging might work.

Next time I'll just get the right yeast first, but I'm still curious as to what kind of pressure is required and what is happening to the yeast to make the taste more neutral.

Ken
 

aaronkaz

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I began using "open" fermentation a few batches ago. Anything I brew with top-fermenting yeast I now primary in an 8 gallon stainless steel megapot. So far, all of these batches have been my best to-date, and my friends who have tasted exclaimed to be of commercial quality. I myself, am impressed as well, really spot on.

I leave the pot's lid on most of the time, loosely if you will, but I open it at least once or twice a day to both see what's going on and ensure any built up off-gases are able to escape periodically. I'm currently re-culturing WLP001 as a "house" yeast for these beers, and starting a belgian culture now (I'm perfectly happy to have just these two around). Another benefit is the ability to skim off hop/grain particulate early and harvest viable yeast from the krausen. This collection method is far superior to using the dregs.

As someone who is actually using this method, I would have to recommend that this is a good way to go. So far, 0 contamination, in fact, I've gotten more contaminations from the fermenting bucket with lid and airlock.

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.

The thing that I feel is the greatest value is that I am much more in-tune with the fermentation process. I can tell when the yeast has reached peak and when its finished. That means my beers get exactly the amount of time needed to complete primary fermentation, no more no less. Another important aspect is that the vessel is wide (not tall like a bucket) which means more surface area for yeast to colonize, thus more contact with wort. Overall, the yeast seems to be free and able to work efficiently, much more so than in a bucket or especially carboy. So far, a 7% beer was finished in 7 days, 5% in 5 days. I wonder if a brew needs a day for each 1 percent??

Anyway, I highly recommend it!
 

eastoak

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I began using "open" fermentation a few batches ago. Anything I brew with top-fermenting yeast I now primary in an 8 gallon stainless steel megapot. So far, all of these batches have been my best to-date, and my friends who have tasted exclaimed to be of commercial quality. I myself, am impressed as well, really spot on.

I leave the pot's lid on most of the time, loosely if you will, but I open it at least once or twice a day to both see what's going on and ensure any built up off-gases are able to escape periodically. I'm currently re-culturing WLP001 as a "house" yeast for these beers, and starting a belgian culture now (I'm perfectly happy to have just these two around). Another benefit is the ability to skim off hop/grain particulate early and harvest viable yeast from the krausen. This collection method is far superior to using the dregs.

As someone who is actually using this method, I would have to recommend that this is a good way to go. So far, 0 contamination, in fact, I've gotten more contaminations from the fermenting bucket with lid and airlock.

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.

The thing that I feel is the greatest value is that I am much more in-tune with the fermentation process. I can tell when the yeast has reached peak and when its finished. That means my beers get exactly the amount of time needed to complete primary fermentation, no more no less. Another important aspect is that the vessel is wide (not tall like a bucket) which means more surface area for yeast to colonize, thus more contact with wort. Overall, the yeast seems to be free and able to work efficiently, much more so than in a bucket or especially carboy. So far, a 7% beer was finished in 7 days, 5% in 5 days. I wonder if a brew needs a day for each 1 percent??

Anyway, I highly recommend it!
how have your subsequent open fermentation batches turned out? my next batch, a hefeweizen, is going to be an open fermentation. it's an experiment to see if the esters and phenols are increased with the greater O2 contact.
 

ECarroll51

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I myself have brewed lets say well over 400 batches and only use open Fermentation, and never ever have had a bad batch, all lagers i might add. It is the way Beer was brewed traditionally, and i try to keep to the old tradition ways, like only using Hops, Water ,Malt and Yeast. Way change a winning team right.
 

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his was the standard procedure for most of beer brewing history. My concern with wild fermentaions would be contamination with acetobacter, giving you malt vinegar. I think though as long as it gets off to a quick start you're fine. It don't know that it would be a beer I'd want to age though as given time, any contaminants could take off then.
You are definitely right on this point, just not for the reasons you think. Acetobacter is in just about every beer produced, but beer prevents it from growing.

In the excellent research paper: Beer-Spoilage-Bacteria-and-Hop-Resistance They state "Today these aerobic bacteria do not present a serious problem in beer spoilage anymore, since improved brewing technology has led to a drastic reduction of the oxygen content in beer".

Open fermentation, if not carefully controlled (monitoring of SG to know when to close fermentation tanks), can allow for much higher levels of oxygen in the finished beer. This increase in oxygen allows for the reproduction of bacteria from the Acetobacter group. These are bacteria present everywhere that will turn your beer into vinegar if you give them enough time (1 week per 1%ABV) and dissolved oxygen.

If you have your sanitation practices down, then I would suggest trying open fermentation to allow the yeast to develop different characteristics. I will be trying this with my next pale ale, the only thing to remember is to be extra careful, and to properly seal the fermenter (ie: airlock) before the beer is done fermenting to allow at least some of the oxygen to be purged from the beer.
 

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i'm trying my first open fermentation, pitched the yeast yesterday at 1630 pacific time and this short video was shot at 0930 this morning.

 
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gr8shandini

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The way I see it, an airlock is already essentially open fermentation. 1" of water is .036 psi. I doubt the yeast can tell the difference between 14.7 and 14.736 psi. So unless you're trying to introduce something wild (or are using 3 feet of water in your blowoff bucket), there's really no reason to change the standard process.
 

eastoak

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The way I see it, an airlock is already essentially open fermentation. 1" of water is .036 psi. I doubt the yeast can tell the difference between 14.7 and 14.736 psi. So unless you're trying to introduce something wild (or are using 3 feet of water in your blowoff bucket), there's really no reason to change the standard process.
i was not thinking of the psi angle but in a sense open fermentation has been the standard process for wits and hefeweizens for at least hundreds of years. beer in general for a lot longer. there is a definite difference between an open fermented beer and the new "standard" process. i'm certainly no expert but i would imagine that the risk of contamination is one of the few reasons this is no longer widely practiced. if the risk can be minimized then there is no reason not to do it, for me anyway. an increase in esters and phenols has been shown with open fermentation which is why i decided to see for myself with this experiment.*


disclaimer: i am not an brew scientist or expert just a wacko with a few sacks of grain, a grain mill, brewing equipment, books and some free time. i could be wrong about everything.
 

eastoak

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this is the first batch of beer where i saw no krausen at all. there is a thin ring of green (hop?) residue right at the top of the beer and that's it. the only thing i did differently is use fresh orange zest so i wonder if the oils prevented the krausen from forming? i'm not worried about the forming or non forming of krausen as it relates to fermentation but the science behind it forming or not. the gravity of the wort before i pitched the yeast (3/11/11) was 1.045 and the reading this morning (3/14/11) was 1.020 so it's moving along.

6 lb torrified wheat
4 lb german pils
.5 lb acid malt (i forgot about another lb i had)
1.3 lb oat flakes

1 oz german saphir 3.7% 60 min
1 oz greman saphir 3.7% 5 min

at flame out for 5 min:
zest of 4 medium/small oranges
1 oz grains of paradise
1 oz indian coriander (kind of yellow, football shaped)

1 liter wyeast forbidden fruit starter
 

gr8shandini

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. . . an increase in esters and phenols has been shown with open fermentation which is why i decided to see for myself with this experiment.*


disclaimer: i am not an brew scientist or expert just a wacko with a few sacks of grain, a grain mill, brewing equipment, books and some free time. i could be wrong about everything.
Nothing wrong with experimentation. However, I think the increase in esters with open fermentation is in reference to the modern commercial practice of brewing under pressure in a sealed fermenter. If you think about it from a chemical perspective, a yeast cell sitting in a bucket/carboy with an airlock is in a nearly identical environment to one sitting in a truly open fermenter. The only difference would be for an open bucket where the significantly larger surface area might lead to some compounds evaporating off. However, since you're trying to increase the amount of "other" compounds in your beer, that doesn't seem like an asset.

I don't know about your setup (youtube's blocked at work), but my favorite "fermentation corner" happens to be in the basement where the spiders, whatever little bugs they're eating, dust from dryer lint, and countless other contaminants abound. I feel better having a lid on it, but if going "naked" works for you, have at it.
 

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If it gets all infected and vinegary...just put a tea bag in it, call it Kamboocha and give it to a hippy friend :D
 

eastoak

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it tastes pretty good so far and it has the color, so far, that i was after. the room it's in does not have any real drafts or HVAC vent, the only real air currents are coming from the crack under the door and whatever comes throught the door when i open it. it's covered up now since my intention was to have it open only during the vigorous fermentaion period and that appears to be over. my next open fermentation batch will be a hefeweizen and i'm trying to get a wide, shallow vessel to ferment in which is what was traditionally used.
 

theredben

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The way I see it, an airlock is already essentially open fermentation. 1" of water is .036 psi. I doubt the yeast can tell the difference between 14.7 and 14.736 psi. So unless you're trying to introduce something wild (or are using 3 feet of water in your blowoff bucket), there's really no reason to change the standard process.
The difference in "open" fermentation is not the removal of pressure, instead it is the natural gas exchange which changes the dissolved oxygen content in the fermenting beer. The theory is that this extra available oxygen allows the yeast to produce compounds they would not normally produce in standard oxygen-deficient beer conditions.
 

aaronkaz

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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
 

wedge421

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I would be way to nervous to try this. Knowing my luck it would get infected the first day. Oh well. Let me know how it comes out if you do it
 

aaronkaz

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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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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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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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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.
 

eastoak

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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.
very well put!
 

ed_brews_now

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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.


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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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.
 

aaronkaz

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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.
 

doctorRobert

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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.

Metaphoric bugs.
 

eastoak

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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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