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O2 and CO2

Discussion in 'General Brewing Techniques' started by SKBugs, 25/1/20.

 

  1. SKBugs

    Well-Known Member

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    Posted 25/1/20
    I hear people talk about adding pure oxygen to their wort, as well as using CO2 whenever they open their fermenters (for dry hopping) etc.
    Where would I get bottles of the stuff and are they critical to beer/cider/mead?
     
  2. JDW81

    I make wort, the yeast make it beer.

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    Posted 26/1/20
    Yep, O2 is used to oxygenate wort prior to yeast pitching, as yeast use O2 early on in their growth stage before they start producing CO2 and ethanol (it's a bit more complex than this obviously). It's an important step, but again something that isn't vital, and you will still make excellent beer without adding O2 prior to pitching your yeast.

    As for CO2 use whenever you open your fermenter I'm not convinced by. The theoretical blanket of CO2 is purely theoretical, and doesn't form and impermeable barrier to other gasses. There will always be oxygen in your fermenter irrespective of the method you use (old bucket style, or new pressurised jobbie), it's almost impossible to exclude it.

    I've never used CO2 when I dry hop, I just try to keep the fermenter open for a short a time as possible. I'd be more worried about bugs getting in than a little bit of O2 from the atmosphere (which remember is only 20.9% of gas in the air). I do purge my kegs with CO2 before filling and then prior to pressurisation, but that is after active fermentation has ceased and there's limited activity from the yeast to mop up any O2 that does make it in. So in my opinion, don't bother with CO2 when you open the fermenter (and don't open it unless necessary) but if you keg then use it.

    JD
     
    MHB likes this.
  3. Frothy Boi

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    Posted 26/1/20
    You could rent either from a company like SUPAGAS or someone similar or you could invest in your own cylinder. Keg king / land have pretty good deals on steel co2 cylinders.I prefer aluminium as it only requires hydrotesting every 10 yrs as opposed to steal that requires retesting every 5 years (if not fitted with a pressure retention valve- AS2030.5-2009 table 1B). Buying a CO2 cylinder and reg is a good investment if you see yourself getting into kegging. I haven't used O2 with brewing but I have heard good things. Just be careful with pure O2 as I have seen it react and vapourise stainless steal tubing in flash. Just avoid contamination of your reg/lines and open the cylinder valve gently.
     
  4. JDW81

    I make wort, the yeast make it beer.

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    Posted 26/1/20
    I use a little bernzomatic O2 cylinder for my wort, with a piece of PVC hose, a simple brass regulator and an aeration stone (which I got from grain and grape in Melbourne). I works well for me, but I can't set a L/min flow and more accurately control how much O2 goes into my wort. I've worked how long to leave it in and how fast to set the flow based on some reading I did ages ago. My O2 setup is about as simple as you can get, but you can get more flash stuff from HB shops or gas supplies (BOC/SUPAGAS etc).

    CO2 is available from your LHBS, where you should be able to get refills and all the other related CO2 gear you may need.

    JD
     
  5. MHB

    Well-Known Member

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    Posted 26/1/20
    JDW81
    I've been doing some testing on getting close to zero O2 in kegs. Mostly because I'm not happy with the shelf-life of some highly hopped beers.
    Best results so far is to: -
    1/ Boil more than a keg full of water.
    2/ At flame out add some Ascorbic Acid and K-Met (O2 and Cl scrubbers)
    3/ Fill keg completely, via the outlet dip tube (well I'm using 50L kegs but same/same) open PRV to get it really full.
    4/ Connect to CO2 and apply a small amount of pressure (~25kPa) while it cools overnight.
    5/ Use a jumper lead to blow all the water out to another keg with CO2, keep keg pressurised
    6/ Counter pressure fill, hasn't got to be complicated, from just a tube from the gas post into a bucket of water, to a spunding valve if your packaging a ready carbonated beer.

    Results so far are looking good, O2 is below test (low ppm range) but I have a better reagent coming which should give accurate results down to low ppb
     
  6. Frothy Boi

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    Posted 26/1/20
    How do you quantify O2 levels, is that dissolved O2 or O2 in the headspace of keg?
     
  7. MHB

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    Posted 26/1/20
    Dissolved O2, I2 / Azure Blue standard method for UV-Vis.
    I'm not set up to measure gas in gas, but DO in water/beer is getting to be pretty easy.
    Mark
     
  8. Frothy Boi

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    Posted 26/1/20
    You have access to an UV/Vis? I have a couple of methods for measuring IBUs as well as SRM, I'll send you a copy if you don't already have them.
    I'd be keen to see your method for DO.

    Edit: sorry this is a bit off course of original thread topic. PM if you're keen for said methods.
     
    Last edited: 26/1/20
  9. MHB

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    Posted 26/1/20
    I just brought a Merck kit, comes with all the reagents and its pretty much an A+B=C
    I got the chance to pick up an old Shimadzu 1201 UV-Vis for very much the right price. Got a centrifuge that I need to make some hangers for 100mL tubes for and Ill be able to do IBU's
    Got the CD from ASBC "Laboratory Methods for Craft Brewers" and a bootleg of the EBC standard methods (pretty much the same methods now days).
    So not far from being able to do IBU's, EBC is a piece of cake (SRM indeed go wash out your mouth :)) just 25*Absorbance at 427.
    Before the development of reasonably(?) priced ISE's and the like there were lots of pretty good wet chemistry spectroscopic methods, sadly most of them are out of use these days but being able to measure Cl, O2, Ca, SO2, even stuff like Redox quickly and at a sensible price (often less than $1/sample) is pretty appealing.

    I'll PM you my email, Always worth looking at options, likewise any info I have that you need just ask.
    Mark
     
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  10. JDW81

    I make wort, the yeast make it beer.

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    Posted 27/1/20
    Sounds like a promising process.

    Probably a little involved for me at the moment. Struggle to find time to brew and get it fermented as it is(hence my planned move to single vessel, electric brewing from 3V RIMS).

    My Hoppy beers tend no to last too long, so shelf life isn't a massive issue at the moment. I usually only brew hop heavy beers in the summer, and there's always plenty of help to drink them.

    I'll stick to O2 in my wort pre-fermentation, and try an minimise it post.

    JD
     
  11. wide eyed and legless

    Pro Pro

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    Posted 27/1/20
    Depends also what yeast you are using, for a lot of the dry yeast they do not recommend aerating or oxygenating the wort.
     
  12. SKBugs

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    Posted 27/1/20
    I’m mainly a dry yeast kind of brewer and I generally just use the aeration wand to stir the crap out of the wort.
    At 1.050 ish OG I figure it shouldn’t need much more to kick the yeast into gear. I don’t degas beer like mead so I was thinking only for dry hopping etc where I have to take the kid off.
    MHB left me fat far behind I’m afraid, but it’s all good if someone learnt something
     
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