Overgravity Brewing

[verysupple]

I wonder if you could pre-fill your kegs with the required (boiled) water and sit it under CO2 & flush out the gas space a few times over a few days?

I don't think that'd work. Putting more CO2 into solution doesn't change how much O2 is (or can be) in solution.

EDIT: I just realised you siad boiled water. That might work if boiling gets rid of all the oxygen and you thoroughly purge the kegs with CO2 first.

 

[technobabble66]

Yeah. True. Partial pressures and all that.
Back to just boiling then I s'pose.
Maybe another option could be to dilute it out while there's still a few points of gravity left to ferment out. That way if there's any oxygen still in the water, the yeast might scavenge it out.
Of course that defeats the FV space saving element.
For me that's no problem: I currently seem to end up with a combo of higher- than-expected OG plus extra boil off in a sub-sized system means I generally get 17-20L into the FV whereby I need to dilute back out to 25-27L to hit the intended OG. So I'm adding back 30-40% volume at pre-fermentation. Maybe I could just do that at the end - either just before or after FG is reached.
OTOH, dropping from 30L FVs to 20L FVs means more FVs in the fridge! Though I'm not sure I brew enough to fill extra FVs...

 

[technobabble66]

I don't think that'd work. Putting more CO2 into solution doesn't change how much O2 is (or can be) in solution.

EDIT: I just realised you siad boiled water. That might work if boiling gets rid of all the oxygen and you thoroughly purge the kegs with CO2 first.

I think it might only make a difference in that you could put the hot boiled water straight into the keg and flush it w CO2 while it cools, then bring in the beer.
So it prevent O2 getting back into the water as it cools (is this even an issue?) and probably makes handling easier in terms of reducing splashing etc (maybe?).
Hopefully someone will chime in with the level of O2 in boiled water...

 

[technobabble66]

http://docs.engineeringtoolbox.com/documents/639/oxygen-solubility-water-2.png

Dissolved oxygen in water at 100*c is 0.0000g/L

The next question is how quickly does it dissolve back in?

 

[technobabble66]

http://docs.engineeringtoolbox.com/documents/639/oxygen-solubility-water-2.png

Dissolved oxygen in water at 100*c is 0.0000g/L

The next question is how quickly does it dissolve back in?

Edit: Added actual image


EDIT 2: this appears to be a bit inaccurate. Read below posts

 

[technobabble66]

Oh bugger. Further googling indicates O2 is not completely removed.
Link to a scientific paper:
http://www.sciencedirect.com/science/article/pii/003991409480110X?via=ihub
Unfortunately it's just the abstract, but it indicates bubbling with N2 (or Argon) flushes out O2 the best (0.2-0.4ppm), with boiling being the worst option.
But without knowing the threshold of what makes a concerning level of O2 in brewing, it's hard to say if boiling is inadequate for our purpose or if it's good enough.

 

[verysupple]

http://docs.engineeringtoolbox.com/documents/639/oxygen-solubility-water-2.png

Dissolved oxygen in water at 100*c is 0.0000g/L

The next question is how quickly does it dissolve back in?

I haven't got sources but it dissolves back in pretty quickly when exposed to the atmosphere. As you mentioned, putting it into the keg while boiling/very hot and fluching with CO2 would help.

Oh bugger. Further googling indicates O2 is not completely removed.
Link to a scientific paper:
http://www.sciencedirect.com/science/article/pii/003991409480110X?via=ihub
Unfortunately it's just the abstract, but it indicates bubbling with N2 (or Argon) flushes out O2 the best (0.2-0.4ppm), with boiling being the worst option.
But without knowing the threshold of what makes a concerning level of O2 in brewing, it's hard to say if boiling is inadequate for our purpose or if it's good enough.

I'm glad you found that because I wasn't convinced that boiling emilinated O2 completely.

I still think the easiest way to avoid oxidation is to let the yeast do the work for you. So I agree that adding water either when transferring the wort to the FV or at least before fermentation has finished is the best/easiest option.

Having said all that, as homebrewers we will always allow a bit of O2 in when packaging and it doesn't seem to be a problem (perhaps because there's still at least some yeast in suspension to scavenge it) - most of us would get at least a few months shelf life before noticeable oxidation sets in. So maybe we're just being a bit paranoid.

 

[technobabble66]

I haven't got sources but it dissolves back in pretty quickly when exposed to the atmosphere. As you mentioned, putting it into the keg while boiling/very hot and fluching with CO2 would help.



I'm glad you found that because I wasn't convinced that boiling emilinated O2 completely.

I still think the easiest way to avoid oxidation is to let the yeast do the work for you. So I agree that adding water either when transferring the wort to the FV or at least before fermentation has finished is the best/easiest option.

Having said all that, as homebrewers we will always allow a bit of O2 in when packaging and it doesn't seem to be a problem (perhaps because there's still at least some yeast in suspension to scavenge it) - most of us would get at least a few months shelf life before noticeable oxidation sets in. So maybe we're just being a bit paranoid.

Yeah - it might be best to add the (post-boiled) water after (?) 75% of gravity points are consumed - that should roughy hit a point where there's still plenty of activity to ensure it's O2 is consumed, and probably equates to being after the first 3-4 days of fermentation where the majority of the flavours seem to be achieved.
Hell, you could even do it as part of a double drop, like those old codgers doing their true-to-style historic/classic UK beers.

And yes, there's a good chance that boiling and cooling is enough, and we're just being paranoid.

 

[dblunn]

Hi FB, the significant factor pre/post fermentation top up is the dissolved oxygen in the water. Pre ferment it is a good thing but post ferment it is a bad thing so take care at removing it or your beer will go stale very quickly.
Dave

Oops, left this on my screen for a couple of hours before ready and replying. All been covered by others in the meantime.

 

[Fat Bastard]

What if I boil and chill the water in a keg, then add the OG wort and carbonate in the keg with a spunding valve and some sugar/DME? D'y reckon that would scavenge enough oxygen? I don't mind a cloudy saison, it is to style after all!

 

[Dunkelbrau]

If you keep the DO of the water low enough it will be around what most craft breweries use anyway. There is no beer with Zero PPB of O2.

I'd boil water, and while hot bubble co2 through a stone to drive off the O2, making sure its from the bottom of the keg, but its a big waste of money for the time frame required to get the DO down that far.

People are forgetting that the rate of oxidation increases with temperature, keep your beer cold and the rate is lowered a lot. We will probably drink the entire keg before it starts showing signs of oxidation at those temps!

 

[RdeVjun]

I would experiment at a smaller scale and lower dilution rate before stepping up to full cornies at 1:1.
I think most of the salient points have been covered above, there are elements of paranoia but OTOH it doesn't hurt to cover as many bases as possible. As related, the technique is in use amongst the commercial players, however I don't know if the push it to quite these extremes.
FWIW, my own experience with this technique was prior to development of MaxiBIAB when I was aiming for more than 12- 14L into packaging from Stovetop All- Grain in a 19L kettle, I tried it a few times on Thirsty's suggestion. It did indeed work and while the results were adequate they were fairly underwhelming compared to other the same non- post- ferment diluted beer particularly WRT to late hops character, so YMMV.
Cooling thoroughly boiled water in a closed cornie is a very sensible idea although bear in mind that as per No- Chilling in one, cooling contraction will suck in air as they are pressure vessels, not designed with partial vacuum in mind. Nevertheless I doubt that would be a biggie.
My 2c, hope this helps!

 

[Fat Bastard]

Yeah, I was kind of worried about chilling in a closed vessel like a keg, but I reckon if I hook the C02 up to it, it should keep it pressurised enough to prevent a vacuum forming and hopefully prevent the O2 from being reabsorbed into the water.

I'm not looking to do award winning beers with this method, kust a nice enough beer to keep the masses happy. Not planning on doing big late additions or dry hopping or anything. It looks like there is some potential with the technique, so I think an experiment may be in order.

 

[RdeVjun]

Yep FB, I suspect that hooking up CO2 to the hot water cornie should nut that issue beautifully. B)

It seems feasible and worth experimentation, I'd give it a whirl and see how it goes. :icon_cheers:

 

[Fat Bastard]

All ready to brew the over gravity wort this weekend. Pretty sure I have my numbers sorted out for a lawnmower saison at the end. Thinking about the DO issues, I reckon that the boiled water couldn't possibly have more than wort, so I'm hoping carbing naturally in the keg with sugar should scavenge enough for it not to be a problem. It's not a beer designed to cellar anyway.

Will report back later.

 

[Fat Bastard]

Quick update: the base saison has dropped from 1.078 to 1.015, giving around 8.3% ABV. I'm hoping it will drop some more to give me somewhere in the region of 9-9.5%, which it looks like it will. It tastes good too, no hot alcohol, and not too heavy on the esters.

I've boiled and kegged 18.5l of water, which I treated with calciums carbonate & sulfate to the same ratio as the base water. This was a bit of a stuff up here, as I did not take into account the expanded volume of the water. I had the keg on the scales and hot water started pissing out of the open relief valve! I dumped a little until the weight indicated I had 18.5kg (and presumably 18.5l) of water inside. I have this hooked up to the gas while it cools.

The next steps will be to split the keg into two, prime the beer with enough sugar for both and top the kegs off with the primed beer out of the fermenter. Then rack myself off to Tasmania for three weeks while they do their thing.

Looks like I won't have time to give it much of a cold crash, so I don't think I'll bother. Saison is meant to be hazy anyway!

 

[Fat Bastard]

I tapped one of the kegs last night, and I'm quite impressed with how the saison has turned out. I've not measured the gravity, but I reckon it's around 4.5% ABV. Plenty of saison esters going on and very smashable. There's no evidence of hot alcohol or fusel flavours.

On the downside, head retention is only moderate and it seems to my palate that there is a bit of mouthfeel lacking.

I'll post some pics of the finished beer tonight, and measure the gravity.

I think this method has great potential and will be doing another over gravity batch soon!

 

[Fat Bastard]

it isn't that hazy in real life, honest!

I.m trying to think of ways to improve the mouthfeel and head retention... thinking some carapils and bumping the mash up to 68 from 67 as a first step.
It's certainly very drinkable, but has some room for improvment. I might leave the other keg for a while and see if oxidation rears it's ugly head. I have a feeling that it won't.

Measured the ABV at 4.7%. Pretty sure the other keg will be lower than this as I assumed they'd be identical in weight and they weren't, so one got a bit more water than the other. No big drama, and something to remember for next time.

 

[verysupple]

Looks appetising, FB. :icon_cheers:

My favourite saison, Saison Dupont, is pretty hazy so I don't think that's a problem.

Good idea about keeping one keg for a while. You're could be taking one for the team a bit there. If it does stale quickly that's not great for you, but then we'll all know. On the other hand, if it's fine then win for you and the rest of us will know the method works.

 

[Fat Bastard]

Cracked the second keg tonight, and no sign of oxidisation. In fact, it's probably tasting better than the first one. Not planning to keep it too much longer, but I reckon it will last reasonably well.

Anyone else want to have a crack? I just brewed my second OG batch today, and I might try out an AAA in the not too distant future.