Open FV, Anyone?

[peebee]

I'm currently listening to the Experimental Brewing podcast. They're talking about an experiment with open/airlock fermenters using Saison yeast. It appears that it made a lot of difference to the speed of fermentation and the dreaded stuck fermentation that a lot of brewers get with Saison yeast. Their feeling were that it's either back pressure or dissolved CO2 in the beer that's causing the problems with the airlock batch or beer. ...

Those "backpressure" or "dissolved CO2" arguments really don't add up. Pressure-wise an airlock adds less pressure than environmental (i.e. weather) changes can account for as any wine-maker with a demijohn of fermented - rather than fermenting - wine can testify: The airlock will operate in both directions in response to the weather. "Dissolved CO2" depends on pressure so will be about 0.9 volumes of CO2 while fermenting (CO2 saturation at atmospheric pressure). When fermentation stops the CO2 "blanket" fritters away in an open fermenter, and so does the dissolved CO2, but that happens after fermentation at the same time as the beer oxidises - so we don't leave the beer like that.

What I'm getting at is can Saisons only be made in inclement (low pressure) weather?

But I'm not putting up alternative ideas to explain it.

Instead I'll say what I do, neither leaving open or sticking on an airlock (not initially anyway). I use cheap (couple of quid?) pneumatic silencers (sort of flashy cotton-wool) like these:

I'm happy with these 1/4" BSP threads (EDIT: oops, mine are 1/2"), but I'm sure they (or something like it) come with barb connections, or whatever, and could replace an airlock directly.

(Note: these are a barrier to critters, not gas or microbes, so beer under them needs putting under airlock when ferment is done).

 

[Nicks90]

So if you are brewing in an open container, do you need to bottle as soon as the fermentation is finished to prevent the co2 evaporating and oxidisation occuring?
Or is that part of the charm?

 

[strange-steve]

Those "backpressure" or "dissolved CO2" arguments really don't add up.

Agreed, I've never bought into the back pressure argument. This often raises its head with regards to saison in general but I'm pretty sure "the dreaded saison stall" is the trademark of just one particular yeast (the Dupont strain WLP565) which is probably the most popular one.

 

[peebee]

So if you are brewing in an open container, do you need to bottle as soon as the fermentation is finished to prevent the co2 evaporating and oxidisation occuring?
Or is that part of the charm?

Some went straight into casks, but a lot went into midterm containers especially so if bottling. Modern practices do this, with conditioning tanks and the like. "Dropping" did the job; "vatting", hundred-and-one other names and techniques. Collectively it all adds up to "secondary fermentation vessel".

 

[MyQul]

This is quite a good vid on open fermentation



As Sadfield mentions, as soon a the krausen starts to drop, a lid is put on the FV. One of the advantages of open fermentation is a big increase in ester production (in the video the bloke recons too much for his hefweizen), so good for yeast (flavour) driven beers like bitters. I might have to have a go.

 

[peebee]

This is quite a good vid on open fermentation. …

Interesting video. Sort of scuppers my remark that open fermentation might have benefits for yeast propagation, but virtually none for flavour in the short term (but if recycling yeast it might develop unwelcome adaptions in closed fermenters a few brews down the line).

The first vessel may well generate differences but that could easily just be "geometry" (shallow; beer fermented under very low hydrostatic pressure). But the second vessel was a bucket. Reminds me of brewing years ago - all that regular "skimming"; a right PITA. But whether the (top-fermenting) yeast generates more esters when it has access to air (the CO2 "blanket" will be a bit transient with air currents in the room creates ebbs and flows of air over the fermenter) - that may encourage some trials? But I'm still happy not taking the risk.

Note a "transient" CO2 blanket is probably going to require no cover at all (like in the video - something I've never tried) for 2-3 days. And this thread has already had discussions about dunking flies, wasps, spiders (pet cat?).

 

[rank_frank]

On the subject of keeping nasties out, I've just checked on my latest brew which is cold conditioning in a keg in the temperature controlled freezer in my shed and I found a slug on the floor of the freezer. I can only guess that it squeezed itself through the tiny gap where the lead for the inkbird probe goes into the freezer. I've heard that slugs go crazy for beer and I'd left the party tap attached to the keg from last week's sample. I expect that there were a few drops of beer left on the tap.

So a lesson learned and a problem to solve before doing an open fermentation in there.

 

[peebee]

Okay, I can add "slugs" to my list of beer bathers mentioned in this thread now (fortunately no-one has confirmed "pet cat").

"Transient CO2 blanket" is not mentioned in the video - that's my view. I believe a bucket with a loose lid will be no different to using an airlock while there is an active ferment. I think the CO2 blanket must be able to momentarily breakdown (and therefore allow air to reach the yeast) for there to be any real effect.

 

[Sadfield]

I guess, if you were to have a loose fitting lid, the action of removing it at intervals you could create a sufficient draft, whilst not allowing any bathers in.

 

[peebee]

 

[strange-steve]

Dunno about a cat but there was a bloke on JBK who had a rabbit fall in his fermenter. Apparently the beer turned out great

 

[hichaechoc]

Second question, I've been looking at a 7 gallon boiler from our local catering manufacturer (Lincat). The nearest I can explain - it's like the Burco 'Cygnet' stainless steel boiler, but no sparge thingy in the base. And it's about 1/4 cost of a bespoke brewing boiler! It has a heater, thermostat, and tap, and max temp is 97 DegC. (controlled range is 30 DegC. - 97 DegC.) would this work?

I've an old Burco which I've modified in 3 ways to enable a rolling boil.
a) Insulated with a camping mat bound into place with gaffer tape. £5
b) Insulated the thermostat probe with a 5cm length of siphon tube. free
c) Used a cheap Chinese voltage regulator to control the heat output. £12
Works for me :-)

 

[JohnB]

Thanks for all your ideas, I'm still reading through your thoughts on this and contemplating possibilities.

If you do plump for open fermentation its a good idea to cover with a cheese cloth to make sure you are insect free if that worries you, especially as it seems to be spider time now the temperature has dropped a little.

I'm currently using a sealed container, but I plan on doing a sort of half-way house thing and covering the bin with muslin tied tightly around the lip. This will give access to the oxygen in 'our world' for the yeast, while keeping out the spiders, fruit flies and fried eggs.

And on the boiler issue, I have solved that through the Home Brew Shop with their Peco boiler. A good bit of kit, after some fiddling and a notepad and playing with the thermostat controls for half an hour. No messing or mods required and I can get anything from a 50 DegC. heat right up to full rolling boil.

 

[Dutto]

............This will give access to the oxygen in 'our world' for the yeast, while keeping out the spiders, fruit flies and fried eggs.

..........

According to some scientists on the Forum, the fermentation process is anaerobic and therefore doesn't need oxygen.

However, I think we are all agreed that it doesn't need spiders, fruit flies or fried eggs; so the muslin should work okay.

 

[BarnBrian]

Those "backpressure" or "dissolved CO2" arguments really don't add up. Pressure-wise an airlock adds less pressure than environmental (i.e. weather) changes can account for as any wine-maker with a demijohn of fermented - rather than fermenting - wine can testify: The airlock will operate in both directions in response to the weather. "Dissolved CO2" depends on pressure so will be about 0.9 volumes of CO2 while fermenting (CO2 saturation at atmospheric pressure). When fermentation stops the CO2 "blanket" fritters away in an open fermenter, and so does the dissolved CO2, but that happens after fermentation at the same time as the beer oxidises - so we don't leave the beer like that.

What I'm getting at is can Saisons only be made in inclement (low pressure) weather?

But I'm not putting up alternative ideas to explain it.

Instead I'll say what I do, neither leaving open or sticking on an airlock (not initially anyway). I use cheap (couple of quid?) pneumatic silencers (sort of flashy cotton-wool) like these:
View attachment 15236
I'm happy with these 1/4" BSP threads (EDIT: oops, mine are 1/2"), but I'm sure they (or something like it) come with barb connections, or whatever, and could replace an airlock directly.

(Note: these are a barrier to critters, not gas or microbes, so beer under them needs putting under airlock when ferment is done).

What about trying a fish tank aeration stone

 

[Sadfield]

I'm currently using a sealed container, but I plan on doing a sort of half-way house thing and covering the bin with muslin tied tightly around the lip. This will give access to the oxygen in 'our world' for the yeast, while keeping out the spiders, fruit flies and fried eggs.

I believe access to oxygen isn't the issue, and could be counter productive, if the goal is to increase ester production. Removing the lid and CO2 blanket however may allow more CO2 to dissipate from the wort, reducing osmotic pressure on the yeast. Ideally, we need to look at changing FV geometry, also, as this plays a greater part.

The following table and blog hold some useful information.

https://edsbeer.blogspot.com/2016/10/ester-synthesis-during-brewery.html?m=1

It suggests to me that the techniques of old breweries using large shallow vats, we're to decrease ester production, eg by aerating, spraying wort to increase yeast growth.

 

[peebee]

What about trying a fish tank aeration stone

Yes. I think it was an "aeration stone" that gave me the idea, followed by a bit of hunting around, and discovering "pneumatic silencers".

… I'm currently using a sealed container, but I plan on doing a sort of half-way house thing and covering the bin with muslin tied tightly around the lip. This will give access to the oxygen in 'our world' for the yeast, while keeping out the spiders, fruit flies and fried eggs. ...

You've received a couple of "stingers" mentioning "oxygen". I was careful to only state "air". When I'm trying to be a clever-dick but haven't a clue, the woolly approach is often best (I learnt that posting on brewing forums!). But as for using muslin - I believe that will be a barrier to light air currents in the room so while the fermentation is active, the "blanket" of CO2 will be quite stagnant and air has no chance of reaching the yeast cap. I guess the best way of seeing this is if you have access to dry ice: Drop some of that in a bucket of water and I think it will illustrate what I'm getting at.

 

[Sadfield]

What's the objective of allowing air/oxygen to the wort?

Shouldn't wort be sufficiently aerated prior to pitching yeast anyway?

 

[peebee]

What's the objective of allowing air/oxygen to the wort? ...

Rats, I should have been clearer:

… may allow more CO2 to dissipate from the wort ...

… which will require contact with air (or any other gas that isn't only CO2) so it can dissipate. Contact with air "takes" as well as "gives". Or, that's what I meant.

 

[JohnB]

... All makes perfect sense. The open FV idea was simply to see if - like the Bateman's open tanks (Yorkshire Squares) - it had any significant effect on the beer in a home-brew situation. I think I feel an experiment coming on here (and risk 5 gallons of beer ).