have any ferment-in-the-keg folks tried high gravity dilution?

[twd000]

I've been fermenting in my corny kegs with good success for about 2 years now. One of the downsides is a smaller batch, since you typically need to allow for ~1 gallon of krausen headspace to avoid blowoff problems.

So I've been fermenting 4 gallons of wort in a 5-gallon corny keg. Often I'll brew an 8-gallon batch and split it into 2 kegs.

Was thinking today about recovering that last gallon of "missing" beer, and how it might fit with closed-transfer processes. It seems you only need the excess headspace until you're past high krausen, then it's safe to fill the keg to the top for serving. Typically you try to transfer to the serving keg with 1-2 Plato remaining so active yeast can scrub any residual oxygen.

This article indicates 20% dilution is quite reasonable, so I could brew a 1.060 beer in order to hit a target 1.048 OG after 20% dilution: High Gravity Brewing | MoreBeer
Writer also stresses the importance of de-aerated dilution water, to avoid oxidation. Well it just so happens that I have a 5-gallon keg of sparkling seltzer water in my kegerator, sitting at 40F and 30 psi.

So my idea is to transfer the 4 gallons of beer ~2 days into primary fermentation after I'm past high-krausen, then push a gallon of seltzer water over to top up the keg.

Any reason why that wouldn't work?

 

[Vale71]

Any reason why that wouldn't work?

Seltzer water is not de-aerated at all, it will contain just as much oxygen as your average tap water does.

 

[twd000]

Seltzer water is not de-aerated at all, it will contain just as much oxygen as your average tap water does.

bummer, so I would need to boil the water first, then add it to the keg

 

[Vale71]

You'd have to add it at flameout and I don't think the keg can handle the sudden increase in temperature, not to mention the effect on the beer. De-aerated water is really out of reach of homebrewers.

 

[twd000]

I'm surprised it would re-absorb oxygen that quickly - you think it would happen in the few minutes it takes to cool down the water to room temp?

https://beerandbrewing.com/dictionary/erYmaGxmwo/
" The methods used for deaerating water vary from very simple to quite complicated and expensive. The simplest is boiling the water, as oxygen has very low solubility in hot water. “Scrubbing” of the water with oxygen-free CO2 or nitrogen is another method, and finally applying a vacuum to water trickling over a large surface (often in a hollow tube filled with small “fillers”) can also be applied. These processes may be repeated or combined to achieve the specified oxygen content required, often 0.01 ppm or lower. "

 

[ba-brewer]

There are people using yeast to de-oxygenate there mash water. Seen someone say that it stays low for a few days if sealed.

I believe I seen people watering down lagers to make lite version and they entered those in contests with good results so it seem some people have figured it out.

If you have carbonated water on tap, maybe dilute to taste on a per glass basis. Maybe add a third keg and top up the other two.

 

[ba-brewer]

@twd000, how long have you let your finished beer sit on the yeast cake?

I am thinking about fermenting a keg but I would like do a lager and it might be a month or two before I drink the beer.

 

[EDF713]

I've thought about doing this as well. I'm wondering how this would work.

Boil water, chill, keg and carbonate. A pre-boiled seltzer.

Brew a higher gravity beer, targeting 4 gallons, fermented in a corny.

Transfer a gallon to the 4 gallon batch at the time you would spund. Either in the fermenting keg or transferring both to a serving keg. Personally, I would add the water to the fermenting keg at the time I start spunding, then transfer after spunding to a serving keg.

 

[twd000]

@twd000, how long have you let your finished beer sit on the yeast cake?

I am thinking about fermenting a keg but I would like do a lager and it might be a month or two before I drink the beer.

I've let it sit for a month on the yeast cake with no ill effects. Two months might be pushing your luck

Cold temperatures buy you more time, as autolysis happens much more slowly if it's stored cold.

If you have a proven method to do a closed oxygen-free transfer with yeast activity towards the tail-end of fermentation, that is a safer bet

 

[twd000]

I've thought about doing this as well. I'm wondering how this would work.

Boil water, chill, keg and carbonate. A pre-boiled seltzer.

Brew a higher gravity beer, targeting 4 gallons, fermented in a corny.

Transfer a gallon to the 4 gallon batch at the time you would spund. Either in the fermenting keg or transferring both to a serving keg. Personally, I would add the water to the fermenting keg at the time I start spunding, then transfer after spunding to a serving keg.

yeah that's similar to my line of thinking. The only question as raised above, is how soon post-boil does the water re-absorb oxygen? Minutes, hours, days?

 

[EDF713]

yeah that's similar to my line of thinking. The only question as raised above, is how soon post-boil does the water re-absorb oxygen? Minutes, hours, days?

I have no idea, hoping someone else would know. I'm assuming the seltzer is fairly low oxygen if it's chilled and kegged quickly, with some potassium metabisulfate, maybe even add some more when transferring.

 

[Bilsch]

There are several solutions to this problem.

First one needs to know that the oxidative reactions that spoil beer happen fairly slowly, on the order of days, at serving temperatures so one could just keep your high gravity beer and at time of serving dilute in the glass with your seltzer water and enjoy since for the time it takes you to drink that glass, there wont be any significant flavor changes. This also has the advantage of letting you try different concentrations.
Secondly making zero oxygen water in a keg is simple. Boil it in your kettle and while still as hot as you can get it, transfer via a short silicone line to the keg. The steam vapor should help in purging the keg although you'd probably be better off transferring to a pre-purged keg. After filling seal and pressurize immediately with CO2, cool then bring it up to your desired carbonation. If you are worried about the rubber parts on some kegs then get a cheap Torpedo brand keg.
And lastly you could put the calculated dilution amount of water in the receiving/serving keg, connect that to the ferment keg where the CO2 created is flowing through and purging the serving keg. That zero O2 environment over the dilution water will draw all O2 out while purging the keg. The when you are ready either spund with residual extract, or fermenter prime, and transfer to the serving keg where the full volume will be carbonated.

These are the first things that come to mind and I will bet there are many more really great ways to solve this brewing challenge. I don't understand why it is the norm for people to be negative about new brewing process. If one takes a minute to think it through you would see there is always a better way to skin the cat.

 

[JimRausch]

One of the methods I've read that the LODO folks do is to preboil mashwater to drive off O2, then add 1 camden tab while it cools down to scavenge residual oxygen. This might work for your "low oxygen" water.

 

[sibelman]

@Vale71 strongly suggests it's quite quick. He usually seems very knowledgeable, but a supporting link or reference would reassure . fwiw, this suggests that hot water might still have considerable dissolved oxygen. Haven't found anything about speed of absorption during cooling. Exposed
surface area *has to* count alot. Right?

Running boiling hot water through a counterflow chiller and then to the liquid post of your keg *should* protect pretty well, but I have no data supporting that claim.

Cheers