Low dissolved oxygen brewing techniques

[Adr_0]

Nice one gents!

 

[Lionman]

I'm skeptical of HSA, but low DO on the cold side, defiantly worth some effort.

One challenge is dry hopping without exposing the wort to air. You could transfer from a pressurised fermenter to a purged keg with bagged hops in it, then after a few days transfer to a serving keg?

I'm also thinking about including a bag of hops in the fermenter from day dot, but there are risks with losing aromatics or over hopping.

Anyone got a solution that works for them?

 

[Mardoo]

I use the purged keg technique.

 

[Lionman]

I use the purged keg technique.

yeah, I might need to get a spare keg for this. The missus will be thrilled...

 

[Danscraftbeer]

I'm skeptical of HSA, but low DO on the cold side, defiantly worth some effort.

One challenge is dry hopping without exposing the wort to air. You could transfer from a pressurised fermenter to a purged keg with bagged hops in it, then after a few days transfer to a serving keg?

I'm also thinking about including a bag of hops in the fermenter from day dot, but there are risks with losing aromatics or over hopping.

Anyone got a solution that works for them?

For me Purged serving keg means. I do the totally filled with san solution then purge out that sanitizer solution with co2. Hold keg upside down to release the last dribbles of sanitizer out all the connections.
Its meticulous, maybe tedious searching for the Holy Grail of beer. Not hard, its easier with this kegmenting unexposed technique. I try hard for no exposure post ferment. Pre ferment I'm not worried.

To dry hop a serving corny keg with minimal exposure to air etc. Purged keg (as above)
The Hop sock: I use a vacuum sealer. 40cm of sealer bag etc. 60g flowers in a boil sterilized weighted hop sock tied with dental floss. All into the new vacuum sealed bag to remove all the air etc. This is fridge storable.
(put on the san gloves) Cut the bag open just to get in the keg and grab the string/dental floss and tie it to the keg handle. Re Seal the lid and repressurize the pressure transfer the beer.
The hop flower mass is like a filter that your beer passes through so leave it in there.

 

[kaiserben]

Are people adhering closely to this method and pre-boiling their water?

And how do people "condition the malt prior to milling with 1-2% water by weight" ? (and specifically I'm wondering if I could rock up to my LHBS and ask to have it done there).

 

[Adr_0]

I have been doing the bakers yeast + LME. I pre-dose with some ascorbic acid for dechlorination before the yeast goes in which also potentially takes up some O2. Generally by the time I do some morning routine and crack grain that's 1-1.5hrs. Obviously it's all sealed up.

I then underlet into the mash tun where generally 400-500mg of sodium met is waiting. Grain I crack dry but will normally do into a bit pre-filled with CO2 and have a stream of CO2 over the grain too. That goes in a bag which then goes straight into the mash tun, sealed again and away.

For sparging I have a cube or two, similarly with sodium met in the bottom but normally 200-300mg. The leftover (sparge) volume in my HLT will be boiled up for a couple of minutes then would have cooled down enough to 70-85°C, then transfer into the cube. The cube then goes into the suction header of my pump and straight into the mash tun - which hasn't been opened since I put the bag of grains in.

Then before transfer, another burst of CO2 into the bottom of the kettle.

Oh, and obviously make up with a fair chunk of CaCl2 - generally mine is in the 8-12g region for 20-22L of beer. The first time I tried this with a brown ale I ended up short and with some astringency - from the sodium met oxidising to sulphate.

 

[labels]

Are people adhering closely to this method and pre-boiling their water?

And how do people "condition the malt prior to milling with 1-2% water by weight" ? (and specifically I'm wondering if I could rock up to my LHBS and ask to have it done there).

I don't pre-boil the water mainly because I don't have time to boil and then cool but there is no doubt boiling will reduce DO. 100mg of sodium met per litre does help.
Conditioning malt normally refers to dampening the malt prior to milling to help keep the husks from breaking up too much - finely ground husks can lead to astringency issues (though usually combined with high pH) and really has nothing to do with dissolved oxygen. I doubt your LHBS will wet the malt. The amount of water added depends on type of mill, mill speed and gap and can vary widely. It also needs to be milled very quickly after spraying, before the water soaks into the seeds, it's only the husks you want to dampen.

 

[kaiserben]

Just looking at the info in the article more closely and thinking about NOT pre-boiling:

* Recommended to add 100 mg/L SMB. That will add 24 ppm Na and 76 ppm Sulfur compounds.

* 5 ppm sulfite will scavenge 1 ppm DO.

* Therefore 76 ppm Sulfur compounds will scavenge 15 ppm DO (not a static amount, but over time).

* Tap water will have 8 - 12 ppm DO.
* Doughing in adds 1-3 ppm DO.
* Atmosphere adds 1-2 ppm DO per hour.

Without pre-boiling, you're likely to have up to 18 ppm DO to remove in total.

So I'm thinking; if your 100mg/L dosage of SMB can deal with 15 ppm, could you just bump the dosage up so it can deal with 18 ppm? I think that would be 120 mg/L, which would introduce roughly 29 ppm Sodium and 91 ppm Sulfur compounds. 29 ppm Na isn't a problem.

Does anyone have any thoughts (or corrections) to this?

 

[Lyrebird_Cycles]

* Recommended to add 100 mg/L SMB. That will add 24 ppm Na and 76 ppm SO4 compounds.

Actually it will add 24ppm Na+ and 101 ppm SO4 2-. The SO4 2- comes from oxidation of SO2 so the mass of the extra oxygen must be counted*.

100ppm of SMS will add about 67ppm SO2, which will react with about 17 ppm of O2 if given enough time (100 x 32 / 190 = 16.8).

* This is a gloss for clarity. There's a hydration step in between.

 

[kaiserben]

I guess one issue might be how long it takes for the initial 12 ppm DO to be scavenged (and the fact that it keeps getting added back via the atmosphere at a rate of 1-2 ppm per hour (so you can't just dose it and then leave it overnight).

I know the article says to leave it for 5 minutes after adding 100 mg/L of SMB, but that when you only need to scavenge a little bit of DO left over after boiling.

 

[kaiserben]

EDIT: My next question became redundant as Lyrebird_Cycles subsequently explained it.

 

[Lyrebird_Cycles]

Yeah, sorry about that, I was editing as you were typing

 

[Adr_0]

Actually it will add 24ppm Na+ and 101 ppm SO4 2-. The SO4 2- comes from oxidation of SO2 so the mass of the extra oxygen must be counted*.

100ppm of SMS will add about 67ppm SO2, which will react with about 17 ppm of O2 if given enough time (100 x 32 / 190 = 16.8).

* This is a gloss for clarity. There's a hydration step in between.

I worked it out this way too, which effectively requires more CaCl2 to balance this additional sulphate - particularly in beers with roasted malts or moderate colour drier beers.

 

[Adr_0]

Actually it will add 24ppm Na+ and 101 ppm SO4 2-. The SO4 2- comes from oxidation of SO2 so the mass of the extra oxygen must be counted*.

100ppm of SMS will add about 67ppm SO2, which will react with about 17 ppm of O2 if given enough time (100 x 32 / 190 = 16.8).

* This is a gloss for clarity. There's a hydration step in between.

Actually I'm curious about this - my original SO4 number was 96mg, but that was based on a 190mg addition of SMBS. Wouldn't the SO2 just gas off? And the SMBS decomposes in water to SBS so wouldn't really get the chance to be heated.

Na2S2O5 + 2HCl >> 2NaCl + H2O + 2SO2, or
Na2S2O5 + H2SO4 >> Na2SO4 + H2O + 2SO2
Na2S2O5 + H2O >> 2NaHSO3-

Which then, with O2 becomes:
2NaHSO3- + O2 >> Na2SO4 + H2SO4

So do we assume that half of the SMBS is being broken down by H2SO4 as well? It's still a 1:1 molar conversion from SMBS to sodium sulphate - and with which cation will the SO4 (from SO2) bond? Won't it still just gas off before it bonds to anything?

 

[Lyrebird_Cycles]

Actually I'm curious about this - my original SO4 number was 96mg, but that was based on a 190mg addition of SMBS. Wouldn't the SO2 just gas off? And the SMBS decomposes in water to SBS so wouldn't really get the chance to be heated.

Na2S2O5 + 2HCl >> 2NaCl + H2O + 2SO2, or
Na2S2O5 + H2SO4 >> Na2SO4 + H2O + 2SO2
Na2S2O5 + H2O >> 2NaHSO3- (sic)

Which then, with O2 becomes:
2NaHSO3- + O2 >> Na2SO4 + H2SO4

So do we assume that half of the SMBS is being broken down by H2SO4 as well? It's still a 1:1 molar conversion from SMBS to sodium sulphate - and with which cation will the SO4 (from SO2) bond? Won't it still just gas off before it bonds to anything?

I think you have confused yourself.

The easier way to think of this is to ignore the cations, they aren't contributing to the reactions.

The metabisulphite anion (S2O5 2-) dissolves in water as the sulphite anion* (2 x HSO3 -) if you look at the stoichiometry there the difference is H20.

The sulphite anion reacts with oxygen to form sulphate anion (SO4 2-). That's why we add it.

The H becomes a proton (H+) by donating the extra electron, we then drop it as we are ignoring cations, so the stoichiometric difference is O.

I mole of SMS weighs 190g. 2 mole of sulphate anion weigh 192 g. Therefore we get about 101% yield of sulphate anion if the SMS is fully oxidised

At normal pH there won't be enough molecular SO2 to matter: the pK is 1.53 so at water pH there is less than 0.001% dissociation.


* Again this is a gloss for clarity: there is an equilibrium between the two which is strongly affected by pH. The sulphite reacting with oxygen removes it from the equation, driving the equilibrium in that direction.

 

[Adr_0]

I think you have confused yourself.

The easier way to think of this is to ignore the cations, they aren't contributing to the reactions.

The metabisulphite anion (S2O5 2-) dissolves in water as the sulphite anion (2 x HSO3 -) if you look at the stoichiometry there the difference is H20.

The sulphite anion reacts with oxygen to form sulphate anion (SO4 2-). That's why we add it.

The H becomes a proton (H+) by donating the extra electron, we then drop it as we are ignoring cations, so the stoichiometric difference is O.

I mole of SMS weighs 190g. 2 mole of sulphate anion weigh 192 g. Therefore we get about 101% yield of sulphate anion if the SMS is fully oxidised

At normal pH there won't be enough molecular SO2 to matter: the pK is 1.53 so at water pH there is less than 0.001% dissociation.

Aha. I've gone to Na2SO4 (sodium sulphate) + H2SO4 rather than the simple and logical 2NaHSO4 of sodium bisulpate.

That's good - because my senses tell me there is a lot more sulphate ending up in the beer than the 50ppm I get for a 100ppm SMBS dosage.

Thankyou kindly.

 

[Adr_0]

And so for ascorbic acid, C6H8O6 and 176g/mol we're looking at:
2C6H8O6 + O2 >> 2C6H6O6 + 2H2O
(plus some dissociating in water and getting to the same end products?)
or 32mg of O2 will oxidise 352mg of ascorbic acid, requiring 11mg/L AA for every 1mg/L O2

I think like many things a couple of approaches can be good rather than putting your eggs in one basket. Time to preboil and cool the strike water is time- and effort-consuming, but using yeast and LME isn't that much better - but if 6ppm (DO in water at 40°C) can get down to 2-3ppm in 20-30min that's pretty good. If 100mg/L SMBS is added that's enough to protect against an accumulation of up to 17mg/L but it does give you 101ppm sulphate on top of your existing water. Not good for a dark beer. So you do need to add enough CaCl2 to get 50-200ppm for your 100ppm of additional sulphate.

That's not really that big a problem, but if it is then ascorbic acid can be used as well with no residual sodium or sulphate. It does need 11mg/L vs 6mg/L for each mg/L O2 though.

And further to this, CO2 purging can be done with some setups - the grains, filling the mash tun with CO2 then underletting, and filling the kettle with CO2 before the first runnings, then getting up to temperature ASAP.

 

[dent]

Just a reminder to be careful with the sodium meta additions. It tastes pretty awful if there's much left in the finished beer - it reminds me of bottom-dollar cider.

 

[Adr_0]

Just a reminder to be careful with the sodium meta additions. It tastes pretty awful if there's much left in the finished beer - it reminds me of bottom-dollar cider.

Yes exactly - it's quite likely that with a lot of systems some of the sodium bisulphite won't be oxidised, hence my inclusion of CO2 purging, yeast/LME in the strike water and ascorbic acid so that I can reduce the SMBS. I'm more in the 20mg/L range than 100mg/L.