Open fermentation & Why ?

[Majed41]

I saw a documentary last night from Germany where a Beer brewery does Open fermentation . with all O2 and the Bacteria in the AIR how this not ruined and no they didn't mention anything about filtration ? it goes against every thing we learn here as newbie . what we missing ?

also what' the point of Open fermentation ?

 

[hotbeer]

It a age old process that some are still able to do successfully.

I don't don't see it any different than any of the other processes we use to make beer. It just a tool or option that someone can choose if it fits their desires and works in their environment.

 

[odie]

been done for thousands of years.

now I wouldn't try it next to the local dump or sewage plant or in a big city with smoggy air...

If you lived out in the country I'd give it a shot.

 

[Cheshire Cat]

Open fermentation happened in the UK big cities with insanitary and smoggy conditions for hundreds of years. However maybe the drinkers weren’t that bothered then.

 

[@RoyalGallon]

In the 90s I worked at Cannon brewery in Sheffield UK. All the fermentation there was done in open squares - basically massive SS swimming pools.

The danger was the rooms that held about a dozen of these would soon be full of CO2 so sampling the FVs was dangerous.

In terms of location it was bang in the middle of one of the most industrial areas of Sheffield surrounded by dirty industrial factories. No issues for the beer with this!

 

[whattabrau]

I feel that open fermentation improves yeast expression, though I haven't done side-by-side comparisons for the same batch. Plus, I top-crop yeast when possible, so open fermentation avoids having to opencloseopenclose.

Also, open fermentation [at least in theory] improves the supply of oxygen to yeast. Remember that yeast needs oxygen, and that the saturation level of oxygen under atmospheric conditions is about 8mg/L and only about 12mg/L with an oxygen wand. Since the oxygen gets consumed in a few hours after yeast pitch, allowing 24-48h for more oxygen intake with open [pre-]fermentation will [likely?] result in a greater total amount of oxygen than from a single dose of pure oxygen. You'll notice the effect of oxygen and open fermentation easily with something more nutrient starved than beer, e.g. wine.

You are correct in that eventually O2 will spoil things. The trick is to either drink the beer before it spoils (a few weeks) or ensure all oxygen is purged while there is still active fermentation and no new oxygen is allowed enter.

Beer does not get infected as easily as we're led to believe. I have a few yeast strains approaching 2 dozen repitches. They've been open-fermented and top-cropped, and apart from having to start adding zinc at around generation 10, they work more or less like out of the packet. (yes I have managed to infect some yeasts, namely closed-fermented ones)

tl;dr prevent air contact starting at the tail end of fermentation, and you're fine

 

[chthon]

I half open ferment my beers, I stretch a cheese cloth over the top of my fermentation vessel, and keep it in a clean room out of the way of air currents. I have the impression my yeasts work more vigorous.

After 8 years of brewing, I have the impression that brewing beer is a more resilient process than people would make you believe on the web, and less prone to contamination and oxidation (perhaps some styles more than others) than is generally told.

Work clean and careful.

Also, in a real brewery with open fermentation, they pitch active yeast immediately. Airborne contaminants don't get the time to wake up in the fresh wort.

I do move my fermenting beer after four or five days to a closed vessel where the fermentation can drive all oxygen out.

 

[hotbeer]

I think most all the breweries that do open fermentation move the beer to a bright tank or other storage when fermentation is nearly complete and the krauesen foam is beginning to subside and expose the beer to air.

Exposure prior to the krauesen isn't an issue.

 

[tdf]

There's a nice blog post from Anchor brewing about their open fermentation:

https://www.anchorbrewing.com/blog/brewing-insights-open-fermentation/

 

[cire]

I open ferment, I have to. Using traditional British top fermenting strains, fermentation vessels would need to be 3 to 4 times the wort volume to keep the yeast within bounds. Open topped allows heat to escape and significantly reduces the volume needed for beers brewed with many traditional yeast that provide flavors other yeast cannot.

 

[patto1ro]

I feel that open fermentation improves yeast expression, though I haven't done side-by-side comparisons for the same batch. Plus, I top-crop yeast when possible, so open fermentation avoids having to opencloseopenclose.

Also, open fermentation [at least in theory] improves the supply of oxygen to yeast. Remember that yeast needs oxygen, and that the saturation level of oxygen under atmospheric conditions is about 8mg/L and only about 12mg/L with an oxygen wand. Since the oxygen gets consumed in a few hours after yeast pitch, allowing 24-48h for more oxygen intake with open [pre-]fermentation will [likely?] result in a greater total amount of oxygen than from a single dose of pure oxygen. You'll notice the effect of oxygen and open fermentation easily with something more nutrient starved than beer, e.g. wine.

You are correct in that eventually O2 will spoil things. The trick is to either drink the beer before it spoils (a few weeks) or ensure all oxygen is purged while there is still active fermentation and no new oxygen is allowed enter.

Beer does not get infected as easily as we're led to believe. I have a few yeast strains approaching 2 dozen repitches. They've been open-fermented and top-cropped, and apart from having to start adding zinc at around generation 10, they work more or less like out of the packet. (yes I have managed to infect some yeasts, namely closed-fermented ones)

tl;dr prevent air contact starting at the tail end of fermentation, and you're fine

Harvey's open ferment and have been repitching for over 60 years. They must be on generation x million by now.

 

[Oleson M.D.]

The folks at Altstadt Brewing employ open fermentation with some beers.

 

[mac_1103]

Harvey's open ferment and have been repitching for over 60 years. They must be on generation x million by now.

I realize this is hyperbole, but...

60 x 365 < 22,000

And it seems unlikely that they ferment in one day and repitch one to one. Probably more like generation 200 depending on when they crop and how much they scale out.

 

[Nixter]

Belgium sours are also open fermented. It's not just the wild airborne yeasts contributing to the flavor its bacteria too. The beams of those Trappist monasteries are a bacterial gold mine.

 

[Clint Yeastwood]

So what about making 5 gallons of wort and leaving it in the backyard without pitching to see what happens?

 

[OleBrewing]

my grandpa told me his uncle used to make great beer out in the ND prairie, they would dig out a hole in the ground in a shaded area of trees and brush. put the vessel in there with cheese cloth over top. not sure on their bottling process or style of beer, and this was back in the early 1900s and descendants of Scandinavia. i am sure it was interesting beer.

 

[chthon]

Belgium sours are also open fermented. It's not just the wild airborne yeasts contributing to the flavor its bacteria too. The beams of those Trappist monasteries are a bacterial gold mine.

The trappists don't brew lambic, only some commercial breweries around Brussels.

And I hate the term "sours" or "sour beer", this implies acidity, but good lambic, gueuze or derived fruitbeers are not sour or acidic, at most a bit tart.

 

[chthon]

So what about making 5 gallons of wort and leaving it in the backyard without pitching to see what happens?

Yep, homebrewers on the Continent and UK do this. But you better split the 5g up in different small batches, and use them as starters after asessing their qualities when fermentation starts.

And only after summer, Sep-Oct.

 

[shetc]

I do a kind of open fermentation for saisons as described by Drew Beechum. A data point in this exbeeriment suggests a detectable difference for closed vs open fermentation:

https://brulosophy.com/2020/02/17/i...tion-on-a-high-og-saison-exbeeriment-results/

 

[Northern_Brewer]

I saw a documentary last night from Germany where a Beer brewery does Open fermentation . with all O2 and the Bacteria in the AIR how this not ruined and no they didn't mention anything about filtration ? it goes against every thing we learn here as newbie . what we missing ?

also what' the point of Open fermentation ?

It's just how things were always done - would you ask what's the point of buying lots of stainless steel and chillers? Take a look at some traditional Yorkshire Squares at Sam Smiths :

So a couple of things are obvious - one is that there's no stainless steel in sight apart from the fishtails used to recirculate the wort and aerate it. But the squares themselves are just big slabs of slate, and making big slabs of stone is something that goes back into antiquity, it's a low-tech thing. Whereas stainless steel dates back less than 200 years - heck chromium wasn't even discovered until 1800 or so.

The other is that they're using a proper top-fermenting ale yeast, which forms a thick barm on the surface which keeps out oxygen and nasties. But nasties are also reduced by generous hopping, and by pitching healthy yeast that soon outcompetes them, or kills them with alcohol. And in general traditional British breweries are less bothered about oxygen because their production was going into cask where a touch of oxidation is unavoidable. Whereas if you're producing helles lager or NEIPAs then you are much more concerned about oxygen ingress.

I realize this is hyperbole, but...

60 x 365 < 22,000

And it seems unlikely that they ferment in one day and repitch one to one. Probably more like generation 200 depending on when they crop and how much they scale out.

Typically they're working on a weekly cycle - but for instance Lees have been repitching their yeast since 1967 and in 2019 celebrated their 5000th generation, implying an average of one generation every 3.8 days :
https://www.jwlees.co.uk/brewery-journal/2258

 

[PCABrewing]

It's just how things were always done

And when it all started most windows probably didn't have glass either

 

[chthon]

I have the impression (didn't measure it in any way, except observation) that my fermentation takes off faster, or starts getting faster, when I remove the lid from my fermenter. That is, from a couple of small islands on the wort, after a night with the lid on, to an active kraüsen within a couple of hours after removing the lid. (Could of course be coincidence, but maybe I had too many such coincidences).

In a time when there was no oxygen to add to wort, and no knowledge about micro-biology and fermentation, this could probably be a reason for open fermentation.

 

[jambop]

Much of the best brewed Germany beers, and we know how much you love them in the US, are open fermented , also Belgian... and of course the best of British!

 

[RM-MN]

also what' the point of Open fermentation ?

When a batch of beer is done the fermenter will need cleaning. Have you ever tried to climb through the bung of a carboy to scrub the inside?

 

[adyb]

Have a look at this for open fermenting, their beers are great.

 

[mac_1103]

Have a look at this for open fermenting, their beers are great.

Looks like that should translate to homebrew scale perfectly.

 

[odie]

that picture...also note how clean the room is. And guy in a lab coat.

cleanliness and sanitation go a long, long way in brewing.

 

[hotbeer]

Also how long does beer stay in these open fermenters? Seems that not very many days after the kraeusen the beer is moved to a bright tank or other closed vessel for a time to clear up and clean up before bottling. Which is essentially what our closed FV's become after just 4 days.

 

[adyb]

Also how long does beer stay in these open fermenters? Seems that not very many days after the kraeusen the beer is moved to a bright tank or other closed vessel for a time to clear up and clean up before bottling. Which is essentially what our closed FV's become after just 4 days.

I'm sure they ferment really quickly, something like 3 or 4 days but can't remember what I was told now

 

[adyb]

They use to use open fermenter at fullers brewery, and what struck me about the old open fvs was just how shallow they were, completely different shape to modern FVs

 

[cire]

Open fermentation in Britain takes 2 to 3 days, initially with rousing to return the yeast to the wort, else fermentation would be slow with a small portion of the yeast active. The yeast is cropped for future pitching, after which the beer is cooled as fermentation nears completion.

The process uses a particular type of yeast, one that rises and flocculates on the top of the wort. It won't work in tall narrow vessels that aren't wide enough to accommodate the yeast so produced. It is not possible for other types of yeast to work in the same manner.

The original yeast that Harvey's obtained from John Smith's in 1957, as seen in the earlier video, can be obtained from Brewlab in UK, Their code for that yeast is 48.

 

[hotbeer]

I'm sure they ferment really quickly, something like 3 or 4 days but can't remember what I was told now

I'm sure they do ferment in 3 or 4 days.

My point is that soon after fermentation is completed and before the kraeusen foam disappears, the beer is moved to a closed system much like what my FV becomes after my beer has fermented in that same 3 to 4 days.

Open fermentation isn't as much of a risk if yeast is going to be pitched. A proper pitch of healthy yeast should quickly out pace any contamination of wild yeasts and bacteria. But after the ferment is over and the foam starts to disappear, then contamination will start to be an issue.

Which is why most of the few breweries still doing open fermenting to my current knowledge move it to a bright tank. They don't leave it in that open ferment vat till the beer is clean and clear and ready for bottling. And that to me doesn't seem any different than what my FV becomes for the 10 days to 6 weeks after the beer in it finished fermenting.

It is probably only those that want to do open fermentation depending on wild yeast to make a good beer that are more of a gamble and more dependent on environmental and sanitary conditions in their particular area.

 

[cire]

I'm sure they do ferment in 3 or 4 days.

My point is that soon after fermentation is completed and before the kraeusen foam disappears, the beer is moved to a closed system much like what my FV becomes after my beer has fermented in that same 3 to 4 days.

Open fermentation isn't as much of a risk if yeast is going to be pitched. A proper pitch of healthy yeast should quickly out pace any contamination of wild yeasts and bacteria. But after the ferment is over and the foam starts to disappear, then contamination will start to be an issue.

Which is why most of the few breweries still doing open fermenting to my current knowledge move it to a bright tank. They don't leave it in that open ferment vat till the beer is clean and clear and ready for bottling. And that to me doesn't seem any different than what my FV becomes for the 10 days to 6 weeks after the beer in it finished fermenting.

It is probably only those that want to do open fermentation depending on wild yeast to make a good beer that are more of a gamble and more dependent on environmental and sanitary conditions in their particular area.

Most yeasts have krausen that collapse as fermentation ceases, so are unsuitable for open fermentation for all the reasons feared. If your yeast is like those below, then it could be suitable for open fermentation.

As above, suitable yeasts sit on top of the wort unless forcibly returned. Left unroused the wort would eventually fully ferment, but with only a small percentage active it would take a week or more rather than a couple of days. So the wort is roused for a few minutes every hour or so until fermentation peaks, when the surplus is harvested, or in the case of Yorkshire Squares, retained in its upper section. The wort is then cooled, the wort clears and the crust stays firmly on top.

Above is my open fermentation with a similar yeast after harvesting on day 3. The yeast reached the top of the vessel and a covering left for protection when harvested.

The picture below was taken 4 days later, as the beer was racked and the crust only then began to break up. If the beer was chilled or left for another 2 weeks, then potentially the yeast could sink, but those aren't part of open fermentation procedure.

 

[jambop]

Most yeasts have krausen that collapse as fermentation ceases, so are unsuitable for open fermentation for all the reasons feared. If your yeast is like those below, then it could be suitable for open fermentation.

View attachment 817413

As above, suitable yeasts sit on top of the wort unless forcibly returned. Left unroused the wort would eventually fully ferment, but with only a small percentage active it would take a week or more rather than a couple of days. So the wort is roused for a few minutes every hour or so until fermentation peaks, when the surplus is harvested, or in the case of Yorkshire Squares, retained in its upper section. The wort is then cooled, the wort clears and the crust stays firmly on top.

View attachment 817415

Above is my open fermentation with a similar yeast after harvesting on day 3. The yeast reached the top of the vessel and a covering left for protection when harvested.

The picture below was taken 4 days later, as the beer was racked and the crust only then began to break up. If the beer was chilled or left for another 2 weeks, then potentially the yeast could sink, but those aren't part of open fermentation procedure.

View attachment 817414

There is no substitute for knowing what you are talking about

 

[gewehr43sniper]

sanitized open top FV + ale yeast starter, dump chilled beer into, toss in yeast, yeast will quickly take over and push out any bad bacterias in the air.

 

[passedpawn]

My friends and I were at an altstadt (Dusseldorf) brewery and asked for a brewer. I wanted to take some altbier yeast home. Brewer was drunk and we had a great time down in the brewery under the restaurant.
Open fermentors, right next to the bright tanks. I put a bunch more here for anyone curious - lots more photos and video here.

 

[Anti-Hoppist]

Yep, homebrewers on the Continent and UK do this. But you better split the 5g up in different small batches, and use them as starters after asessing their qualities when fermentation starts.

And only after summer, Sep-Oct.

Why after summer? More quality bacteria?

 

[chthon]

Why after summer? More quality bacteria?

I think it got something to do with getting colder. But e.g. grapes also only get natural yeast on their skins after summer.

 

[Anti-Hoppist]

I think it got something to do with getting colder. But e.g. grapes also only get natural yeast on their skins after summer.

I see. I have a friend with some some peach trees, maybe one day I could try to ask to let me "rest" my wort near his trees and see if some magic happens.

 

[mac_1103]

Or maybe just pick a ripe peach?