Closed System Fermentation

[halite]

A couple of weeks ago I was brewing and had decided to do a double batch (about 36L) of a new pale ale recipe. My only issue was that I did not have the fermenting space for two batches, so I decided to try out something that I had seen on youtube. Basically I used one of my corny's as a closed system fermenter. I put 20 liters in my glass carboy and then transferred the remainder into the corny (about 16 liters). Blow off tube comprised of a length of  tubing connected to the gas in connector and then the end in a milk carton. Thankfully blow off was not required and it fermented away in tandem with the glass carboy.

However the cool part comes when you want to jump it to another corny for serving (which I did this morning). A little spurt of CO2 and then a party tap connected to the liquid out let me take a hydrometer reading (1013). It was ready to keg and so I then let the yeast run off, filled the sanitised receiving keg with CO2 and then transferred using a length of tubing with two liquid disconnects at either end, turn the gas on to the fermenting keg, click them on and the beer transfers, as soon as you hear CO2 bubbling into the serving keg, disconnect, give the keg a blast of CO2, purge and fridge.

There are a number of advantages of doing this:
- Fementation vessell is easy to sanitise, and surprisingly easy to clean afterwards
- Its a closed system and so if you sanitise properly there should be no danger of infection or degradation due to air

There are a couple of disadvantages:
- If you want a full 5 Gallons for your serving keg you should either ferment the batch in two corny's (three for 10 gallons), or use something like Fermcap S, as you do not want to clog the gas in because of blow-off
- I heard an episode of Brew Strong where the guys were against using a cormy for fermenting, they said that the shape of the vessel was unsuitable and would have a negative effect on fermentation. So far I have not found that, the fermentation of both batches were exactly the same (start, duration etc) and the taste from the sample was great.

I will do a side by side tasting when I keg the other batch, but I am confident there will be no problem with the corny fermented batch.

Anybody else tried this, or something similar, anybody see any problems with it that I am missing?

[Hop Bomb]

Ive listened to that brew strong podcast too. I think the issue they were on about was the yeast bed. In a corny the surface area is very small in comparison to a bucket or carboy. Because the yeast bed would be much thicker in a corny the core of it can get quiet hot & the yeast die. (its not an issue in a conical as they have a dump valve to drop out the yeast & trub which you cant do in a corny)

[halite]

That fermenting under pressure looks interesting, however I have to say I am not really interested in it from that perspective. It was more to use a closed system, and one that comes with a built in, automatic, tap/syphon 

[Dr Jacoby]

Hi Halite, I ferment this way and I love it!

I split each 20 litre batch between two cornies with the dip tube in each shortened by about an inch. I take samples using a length of 3/16 ID tubing attached to a flared liquid disconnect that I can unscrew. When fermentation is complete I transfer under pressure to a single corny using a jumper lead (a lead with a liquid disconnect on either end). The receiving corny is double purged in advance to get rid of oxygen.

I don't see the need to use 2 cornies during fermentation as a disadvantage. In my temp controlled fridge I can actually fit four cornies, so it means I can ferment two batches at the same time. I can't do this with conventional buckets. Also, cornies are easier to move around than buckets, and much easier to deal with than conical fermenters.

In terms of yeast health, I have had excellent attenuation in my last few batches. With the shortened dip tube I leave all the yeast cake behind, which has improved the clarity of my beers considerably.

The big plus though is the freshness of the beer when served. I notice a big difference between most standard homebrews that have been exposed to oxygen and beers that are brewed in closed systems. The sweetness of the malt is more pronounced (I use less speciality malts now to accentuate malt/caramel/toffee flavours) and the aromas and flavours of the hops are more vibrant longer lasting.

In fact, I don't understand why more people don't go down this route. It's about as close as you can get, post fermentation, to conditions in a commercial brewery.

The only real difficulty is getting your hands on cornies - I have 7 and I wish I had at least 3 more! But once you have them, I don't think you'll look back.

[halite]

Thanks Dr Jacoby. If this beer tastes as good as the sample then I will definitely be going this route from now on. When you take your hydrometer sample do you find you need to dump the first liquid or is the dip tube high enough to avoid picking up any of the slurry? Also with the dip tube this high, is there much wastage when you transfer?

Mark

[Dr Jacoby]

There is usually no yeast in the samples. I'm careful not to disturb the corny when I push the disconnects into place. And I try to dial up the pressure gently so as not to disturb the trub. It's worked out well so far.

I normally budget to lose about half a litre from each corny, but since most of it is yeast gunk it's not a big issue. The way I look at it, I'd rather have 19L of fresh beer than 20L of oxidised beer.

By the way, I don't want to put down beer that is brewed in an open system. We have all tasted great beers that were brewed in carboys and buckets. What I will say though is that I think you are more likely to produce really fresh vibrant beers in a closed system and get more consistent results - this has been my experience anyway.

I should say though that certain styles seem to respond better to closed systems. IPAs, lagers and Alts, for example, seem to respond very well. Imperial Stouts and Barleywines, on the other hand, probably don't need to be so carefully handled.   

I haven't brewed a huge variety of styles in cornies yet so I don't want to say anything too definite but my initial impression is that closed systems are definitely worth a try.

[halite]

Cheers for the advice.

[Stitch]

Blow off tube comprised of a length of  tubing connected to the gas in connector and then the end in a milk carton. Thankfully blow off was not required and it fermented away in tandem with the glass carboy.

I am confused. To me this still sounds like an open system. You are still using a blow-off tube the same way you would with a carboy?? I would have imagined a closed system to be one where you ferment under pressure the way Diageo do. Could the pressure release not have been used on the corny??? I would have though the link Tube gave was a closed system.

Sorry I am just a bit confused but am very interested in this.

Thanks

[Dr Jacoby]

I am confused. To me this still sounds like an open system. You are still using a blow-off tube the same way you would with a carboy?? I would have imagined a closed system to be one where you ferment under pressure the way Diageo do. Could the pressure release not have been used on the corny??? I would have though the link Tube gave was a closed system.

Sorry I am just a bit confused but am very interested in this.

Thanks

The word 'closed' really refers to everything that happens post-fermentation. You could ferment under pressure from the very beginning but this is quite a technical challenge and something that is probably beyond the average homebrewer. It's certainly beyond me!

The blow off tube prevents any oxygen getting at the beer so as long as you can prevent oxygen at later stages you will have a closed system.

Here are the standard options with cornies:

1. Ferment as normal but instead of opening up the cornies and racking or pumping the beer into a non-sealed receiving vessel, you purge the receiving corny of all oxygen and then pump the beer into it under pressure using Co2.

2. Ferment as normal for the first few days and then remove the blow off tube so that the final few gravity points contribute carbonation to the beer (Galway Hooker use this approach on their conical fermenters). You will then have mildly carbonated beer that can be pumped into a purged receiving corny as described above.

3. For lagers, or any beer that you want to age or ferment over a longer period, you can follow option 2 but allow the beer to keep fermenting while it lagers in the receiving corny. To do so you need to have a way to regulate the pressure in the corny so that the yeast can stay active. A bleeder valve serves this purpose very well. I think Tube uses one.

[Ciderhead]

[Stitch]

I am confused. To me this still sounds like an open system. You are still using a blow-off tube the same way you would with a carboy?? I would have imagined a closed system to be one where you ferment under pressure the way Diageo do. Could the pressure release not have been used on the corny??? I would have though the link Tube gave was a closed system.

Sorry I am just a bit confused but am very interested in this.

Thanks

The word 'closed' really refers to everything that happens post-fermentation. You could ferment under pressure from the very beginning but this is quite a technical challenge and something that is probably beyond the average homebrewer. It's certainly beyond me!

The blow off tube prevents any oxygen getting at the beer so as long as you can prevent oxygen at later stages you will have a closed system.

Here are the standard options with cornies:

1. Ferment as normal but instead of opening up the cornies and racking or pumping the beer into a non-sealed receiving vessel, you purge the receiving corny of all oxygen and then pump the beer into it under pressure using Co2.

2. Ferment as normal for the first few days and then remove the blow off tube so that the final few gravity points contribute carbonation to the beer (Galway Hooker use this approach on their conical fermenters). You will then have mildly carbonated beer that can be pumped into a purged receiving corny as described above.

3. For lagers, or any beer that you want to age or ferment over a longer period, you can follow option 2 but allow the beer to keep fermenting while it lagers in the receiving corny. To do so you need to have a way to regulate the pressure in the corny so that the yeast can stay active. A bleeder valve serves this purpose very well. I think Tube uses one.

Ok that makes perfect sense.
Ciderhead is that an automatic blow off valve?? What pressure is it set to?? Looks good

[Dr Jacoby]

It looks like one all right.

I think the one Tube uses can't be set at a particular pressure level. He just reads the gauge and releases pressure manually if it gets too high. The one from H&G I linked to can be set at a specific level and left alone to bleed excess pressure automatically.

[Stitch]

Tube did you have to cut a bit off the dip tube??

[Dr Jacoby]

Go on Shane, shorten the dip tube! You won't be sorry 

[Dr Jacoby]

Ah yes, I remember well that famous interview with the German Ambassador to Ireland in which he scolded us for flaunting our cornies to a jealous outside world. And then there was that banner at the Euro 2012: "Angela Merkel thinks we have no wort". How times have changed.