To open ferment or not to open ferment?

[user 70770]

Good morning/afternoon. I was hoping to hit my favorite online community for some advice/discussion about open fermentation. I was interested in experimenting with it it for my next beer and wanted to see if anybody had any comments or words of wisdom about this somewhat antiquated brewing technique.

If you have experience with both closed and open fermentation, did you notice your beers to be noticeably different when using one method compared to the other? If you did notice a difference/improvement with open fermentation, did you apply it to all styles of beer or do you use it only for certain styles? Assuming proper sanitation protocols are followed, did you ever have any problems with contamination or infection?

Any information is appreciated. Thanks!

 

[TwistedGray]

I've only open fermented sours, and I didn't notice an appreciable difference. I'd do it again either way

 

[Bilsch]

I do it all the time and have a dedicated shallow stainless tank that works great. Advantages are shorter lag times, faster ferments, easier for skimming braun hefe and cropping yeast, healthier yeast and more esters in wheat beers Belgians etc. Disadvantages are it's easier to contaminate and harder to control the temperature without more expensive equipment and a lot of attention is required especially if you are trying to catch a certain point for transfer to spunding. It's way fun though and you get a better connection to your brew since more of your senses are engaged with it. I've learned much from the process.

 

[day_trippr]

I'll readily confess I'm in the "scared of bugs" poll group.
I just feel so invested in the process of producing reliably enjoyable beers I go to OCD extremes to avoid introduction of anything I didn't plan on being in the beer. So, open fermentation is a counter-intuitive risk to me...

Cheers! (Also, I don't like sours )

 

[bracconiere]

i don't do open air....but i don't wash or sanitize my fermenter, just rinse and pasturize.....the only time i get a sour brew, is when i've tried to actually clean and sanitize, weird....but i know it's the same way you have to grow white button mushrooms, or compost lovers, just want pastuerization, not complete sterilization.....

 

[user 70770]

I'll readily confess I'm in the "scared of bugs" poll group.
I just feel so invested in the process of producing reliably enjoyable beers I go to OCD extremes to avoid introduction of anything I didn't plan on being in the beer. So, open fermentation is a counter-intuitive risk to me...

Cheers! (Also, I don't like sours )

Yeah I totally get where you coming from. I've spent years working on refining my process to control as many of the many variables as possible to avoid issues. But after reading a few articles about how the character of a beer is changed based on whether it is open or closed fermented, I got curious.

And one thing that reassured about trying this is the fact that some major breweries in the UK open ferment their beers on a massive commercial scale. I feel that if Samuel Smith trusts their beers to come reliably good with open fermentation since their reputation depends on it, I think it's safe enough to give it a shot.

 

[bracconiere]

just know it won't be LoDo..... lol

 

[user 70770]

just know it won't be LoDo..... lol

Forgive me but what is LoDo short for? Not sure if I've seen that term before.

 

[bracconiere]

Forgive me but what is LoDo short for? Not sure if I've seen that term before.

you haven't heard of lodo yet? there's a trend of brewers that swear by exposing the beer to as little O2 as possible during the entire proccess...(except for the pitch)

almost OCD levels, lol

it's short low dissolved oxygen.....there's a support forum in all-grain so people can get help with it, check it out....

 

[user 70770]

you haven't heard of lodo yet? there's a trend of brewers that swear by exposing the beer to as little O2 as possible during the entire proccess...(except for the pitch)

almost OCD levels, lol

it's short low dissolved oxygen.....there's a support forum in all-grain so people can get help with it, check it out....

Oh gotcha! Now that you mention this, I am familiar with the trend of low oxygen brewing. I just haven't been on the forum much in the last few years and the acronym just didn't ring a bell initially. With that said, I'm not too worried about oxygen during fermentation since the yeast is likely to metabolize all of that.

 

[bracconiere]

Oh gotcha! Now that you mention this, I am familiar with the trend of low oxygen brewing. I just haven't been on the forum much in the last few years and the acronym just didn't ring a bell initially. With that said, I'm not too worried about oxygen during fermentation since the yeast is likely to metabolize all of that.

i'm not worried about it anytime....i don't think i would unless i was bottling for distribution, and worried about shelf life....

edit: back to the topic at hand though, the bubbles are fun to listen too!

 

[monkeymath]

I'm kind of curious about open fermentation, but yeah, bugs AND oxygen scare me just a bit too much. I think it also takes a yeast with the right characteristics, that is, the yeast needs to really form a protective layer on top.

And one thing that reassured about trying this is the fact that some major breweries in the UK open ferment their beers on a massive commercial scale. I feel that if Samuel Smith trusts their beers to come reliably good with open fermentation since their reputation depends on it, I think it's safe enough to give it a shot.

I do not think the standards of hygiene and sanitation in my living room are comparable to those in rooms designated for that purpose in a professional brewery.

 

[Dinadan]

I have never left my beer uncovered. Like others say too may bugs here. But when I brew a small batch I just cover the container with cheese cloth. I miss the gurgling from the airlock, but other than that I do not notice any difference. I have never done a side by side test with cheese cloth versus airlock.

 

[day_trippr]

Yeah, "Batch Size Matters", too. I do ten gallons at a time. For some of my recipes, that's a chunk to risk.
If I did one gallon brews I do believe I'd be inclined to try all kinds of techniques

Cheers!

 

[couchsending]

Russian River open ferments all kinds of beers from Pliny to STS.

Notch does all their traditional Czech lagers in open fermenters...

Both are probably in rooms with sterile filtered air.

it’s pretty common in traditional lager breweries in Europe.

just take the blow off out of the bucket for a few days If you want to get close without worrying so much about contamination. I do it often for lagers in theory to reduce sulfur. In theory...

 

[Vale71]

it’s pretty common in traditional lager breweries in Europe.

No it isn't, except maybe in very small and very old ones. Conicals have been the norm for over half a century now.
BTW there is absolutely no difference between covering the fermenter and leaving it uncovered. The only difference, if any, is due to the different fermenter geometry, with traditional "vats" being shallow and wide and having square corners (because they can't be pressurized). Not placing a lid or an airlock on the very same fermenter is not going to change its geometry so all that is giving you is a higher risk of infection.

 

[Abhishek Dewan]

Where I brew (India and Africa), open fermentation or even no water in airlock definitely leads to lacto infection. I use it while making whisky mash only.

 

[duncan.brown]

My option would be “depends on the yeast and the beer.”

For a top fermenting British ale yeast, I open ferment, cover when the krausen starts to fall, and cask condition. If I’m drinking slowly, I’ll use a CO2 cask breather, but if I have help and I can get through 2.5 gals in less than 3 days, I’ll expose the beer in the cask to air. Because real ale.

But for a lager yeast, I ferment in my closed chronical, serve in a keg, and keep all O2 out after the initial wort oxygenation.

 

[dtashmore547]

yeast is a very powerful organism, it forms it's own anti bacterial and whilst it is in full ferment there is little chance of getting infections unless you are in a very dirty environment also the co2 given off will prevent oxygen entering. once the ferment dies down it would definitely invite infections.

 

[user 70770]

My option would be “depends on the yeast and the beer.”

For a top fermenting British ale yeast, I open ferment, cover when the krausen starts to fall, and cask condition. If I’m drinking slowly, I’ll use a CO2 cask breather, but if I have help and I can get through 2.5 gals in less than 3 days, I’ll expose the beer in the cask to air. Because real ale.

But for a lager yeast, I ferment in my closed chronical, serve in a keg, and keep all O2 out after the initial wort oxygenation.

Yeah I’m biting myself a bit for not having that option in the poll. Clearly open fermentation doesn’t have to be an all or nothing brewing trick. Might be better suited for certain styles/yeast strains. I’m thinking European ales styles (British pale ales, Belgian ales, sours, wheat ales, saisons etc) might work well for open fermentation. American styles ales and bottom fermented beers like lagers would probably turn out better with traditional closed low oxygen brewing (I’m guessing).

 

[Argyll Gargoyle]

No it isn't, except maybe in very small and very old ones. Conicals have been the norm for over half a century now.
BTW there is absolutely no difference between covering the fermenter and leaving it uncovered. The only difference, if any, is due to the different fermenter geometry, with traditional "vats" being shallow and wide and having square corners (because they can't be pressurized). Not placing a lid or an airlock on the very same fermenter is not going to change its geometry so all that is giving you is a higher risk of infection.

Vale,
What is the significance of the square vat? Is the effect just that surface area versus volume of a vat changes that character of the fermentation?

 

[Gnomebrewer]

For anyone looking to open ferment, take note of Bilsch's method in post #3. It's not about leaving the lid off your fermenter for a pressure difference (which is basically zero difference). The idea is to use a flat, shallow vessel that allows the yeast easy access to atmospheric O2 (healthy yeast and more yeast production) which also leads to greater ester production. That's why it's use is mostly in English ales and hefeweizens (maybe Belgians?) where esters are desired. 'Clean' beers use the direct opposite approach - tall conicals. The shallow, flat fermenters also mean yeast is easy to top-crop (healthy yeast) rather than take from the bottom (as with concicals). The vessel needs to be closed off or transferred or bottled/kegged before fermentation finishes though, otherwise oxygen damage will happen rather quickly (once the krausen drops).

 

[greywolf]

I'm more worried about fruit flies getting to it and spitting their goo into my wort.

 

[day_trippr]

Ugh...Good point - hadn't even considered that level of wildlife...

Cheers! ("There's always something" )

 

[Vale71]

Vale,
What is the significance of the square vat? Is the effect just that surface area versus volume of a vat changes that character of the fermentation?

No, it's not the surface area and it's most definitely not access to atmospheric O2 which would only oxidize and ruin the beer even before it's done fermenting. The shape of the fermenter has a direct impact on the convective circulation of wort during active fermentation, which can be quite strong as observed directly by those who ferment in transparent carboys. A shallow, wide fermenter suppresses convection and the square shape does so even more with the edges acting as convective "dead pockets". The ideal shape for maximum convection on the other hand is a tall, round shape like that of a modern cylindroconical vessel.

Convection has a direct effect on fermentation profile, with stronger convection suppressing ester production and reduced convection increasing it. This makes square vessels particularly suited for characterful ales such as tradional British ales and cylindroconicals particularly suited for the production of clean lagers.

 

[user 70770]

There’s some great conversation going on here. My plan was to ferment in my glass carboy as I usually do but leave the stopper off and put a cheese cloth on the opening just to reduce any lint or dust from falling in the beer. Will I see any benefit with that setup or is open fermentation only helpful with shallow fermentors with large openings?

 

[Vale71]

My money is on it won't change a thing other than increase the risk of infection.

 

[duncan.brown]

atmospheric O2 which would only oxidize and ruin the beer even before it's done fermenting.

That’s definitely not a true statement for all types of yeast and beer. The krausen of a true top-cropping ale yeast (e.g. 1469) will protect the green beer from oxygen. I don’t mean that there will be a “blanket” of carbon dioxide (any free gas will mix with the room air), but the yeast cells and bubbles of carbon dioxide that they trap protect the beer. Once the krausen starts to fall, the green beer must be protected from oxygen at which point, it should be covered. For a good example of this, watch the fermention video from the Timothy Taylor YouTube channel:

Convection has a direct effect on fermentation profile, with stronger convection suppressing ester production and reduced convection increasing it.

It would be interesting to see a reference to the professional brewing literature that supports this statement.

One of the classic papers on comparing square open fermenters to cylindroconicals is Shardlow MBAA TQ vol. 9, no. 1, 1972, pp. 1-5. This discusses the switch from traditional square open fermenters to cylindrocomicals at Whitbread in the 1960s. The primary reason for the change was efficiency and economics (not flavor, they obviously wanted to produce the same beer). Shardlow notes that they switched to a bottom-cropping ale yeast for optimum use, but that top-cropping yeats would bottom crop in the cylindroconicals. They do not report any flavor differences due to this.

They do report that beer fermented in cylindroconicals has a 15% increase in retained isohumulomes and an increased retention of foaming agents. They attribute this to the loss of bittering compounds occurred when skimming a krausen of top-cropping yeast. These compounds remain in the beer when a bottom-cropping yeast is removed from the cone. They reduced their hop additions by 15% to maintain flavor.

I believe that the statement that shallow tanks produce more esters originates from a study of wheat beers by Narziss (16th Technological Seminar at Weihenstephan 1983), but I am unable to find the original paper. Obviously British top-cropping ale yeasts are quite different to German Hefeweizen ale yeasts, which are again different from lager yeasts.

 

[duncan.brown]

It's not about leaving the lid off your fermenter for a pressure difference (which is basically zero difference).

Agreed. I’ve seen mention of the pressure caused by air locks causing yeast to behave differently. However, if you calculate the pressure from 4” of water, it’s about 10 millibars. That’s about the same order of magnitude as how much the air pressure changes due to the weather:

https://w1.weather.gov/data/obhistory/KSYR.html

 

[Vale71]

Atmospheric O2, if it could get into the beer, would only oxidize and ruin the beer even before it's done fermenting.

We're basically saying the same thing but I didn't make myself clear. Hope it's clearer now.

 

[Vale71]

It would be interesting to see a reference to the professional brewing literature that supports this statement.

Narziß, "Abriss der Bierbrauerei", 7th Edition, Page 206

 

[Stormcrow]

just know it won't be LoDo..... lol

I'm was scrolling down wondering when the lodo crowd would come in to burn this thread to the ground!

 

[duncan.brown]

Narziß, "Abriss der Bierbrauerei", 7th Edition, Page 206

Unfortunately, there's no English translation of that classic text and, having not spent enough time there, my German is limited to phrases like "Bitte ich möchte ein Andy Teller* und ein großes bier."

* Currywurst mit Bratkartoffeln und 2 Spiegeleiern, Salatgarnitur

 

[duncan.brown]

I'm was scrolling down wondering when the lodo crowd would come in to burn this thread to the ground!

To be fair to the LODO folks, I think this again is a question of beer, yeast, and desired results. They are trying to make modern German lagers where low-oxygen techniques matter. If someone told me they were using LODO methods to make a cask-conditioned British ale, I would... uh... admire their fortitude. CAMRA only allowed the use of CO2 cask breathers on the finished beer in the last few years.

 

[Vale71]

Don't say their name too many times.

I believe an English version of Narziß exists but I don't have it on hand having no need for it, sorry.

 

[Beerhog]

I really wonder how breweries that practice open fermentation keep their beer safe from bugs. Krausen is prime feed for flies. Since abv of beer is not that high, not much ethanol to kill bacteria.

 

[duncan.brown]

I really wonder how breweries that practice open fermentation keep their beer safe from bugs. Krausen is prime feed for flies. Since abv of beer is not that high, not much ethanol to kill bacteria.

I've visited New Glarus and Russian River and seen their open fermenters. Both are in sealed rooms with special air handling systems, so I don't think they worry about bugs. Check out this video from the old Brewing TV YouTube channel for New Glarus:



Here are the Russian River fermenters from the web page of the company that did the construction of their new facility. On the tour, you can look down from the windows above:

https://www.archilogix.com/sites/default/files/styles/gallery/public/DSC_3098_3.jpg?itok=y02J-CrE

 

[user 70770]

I really wonder how breweries that practice open fermentation keep their beer safe from bugs. Krausen is prime feed for flies. Since abv of beer is not that high, not much ethanol to kill bacteria.

The other thing that probably helps commercial breweries is their pitch rate. They pitch very large amounts of yeast which causes beers to finish super quickly. I recall a Sierra Nevada brewery tour where they mention their pale reached final gravity in only 3 days. I usually woefully under pitch all my beers so all my fermentation take 7 days or more. Commercial breweries that practice open fermentation are probably successful because the fermentations are just so short and therefor the window of opportunity for contamination/oxidation to be significally smaller.

 

[Argyll Gargoyle]

I wonder if you could make an “open” fermenter out of a big IBC tote or maybe a 55 gallon barrel with a removable lid? The point being that the container would be large enough to simulate an open ferment, but it would in fact be a closed container. Going off of Vale’s description of wort flow, what if you were to line the bottom of the fermenter with plastic cells (or cups / open containers for lack of a better description) — these would help to break up fluid flow currents in the wort. The level of the wort would be just above the rims of all of the cups.
OK, well it does sound a little far fetched now that I wrote it all out...

 

[duncan.brown]

I just remembered where I saw another data point: In Barrel Aged Stout and Selling Out [J. Noel, 2018, Chicago Review Press] the author describes the problems encountered when moving production of Goose Island 312 wheat beer from the Goose Island plant in Chicago to the AB InBev plant in Baldwinsville, NY. Goose Island used cylindroconicals, but the Baldwinsville plant had "massive horizontal tanks."

The author says that the resulting 312 was different due to tank geometry and pressure, rather than convective motion of the wort:

The broader surface area led to different head pressure on the beer, which resulted in more intense and fruiter esters than what came from taller, skinnier tanks.

Apparently AB InBev dumped more than three thousand barrels of Baldwinsville 312 based on blind taste tests of the Baldwinsville version vs the Chicago version. So I'm guessing that there was definitely a perceptible difference!

Although remember that this is pressure on a commercial fermentation tank scale (3000 bbl batches). Slightly more than 4" of water in an airlock.

I have so far failed to find a journal article on the effect of oxygen (or not) on open fermentation. Still looking.