# O2'ing a yeast starter.



## Dave70 (10/11/17)

My stir plate hasn't turned up yet and I want to pitch this weekend. What I do have on hand id my O2 set up.
Any thoughts on weather giving the starter a quick bubble would be a good / bad idea?


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## Lyrebird_Cycles (10/11/17)

It's a great idea, works a treat.

We routinely used continuous aeration* on the starter cultures at the last large scale winery in which I worked. I ran a trial where I did continuous oxygenation side by side with standard aeration on two cultures; it improved performance** but it chewed through a size G oxygen bottle per day (for one tank) and we had 7 culture tanks so the potential cost freaked the cellar manager out.

I based the oxygen addition rate on the known yeast uptake rate and the expected growth rate but we ended up being a bit low because the growth rate was higher in the Oxy tank. If you tell me your expected growth targets I can calculate the ideal oxy addition if you like.



* Aeration rate was limited by the foaming of the culture: even with 40% headspace if you went too hard half the culture blew out the top. Some idiot designed the yeast culture room with no drain in the floor so that was a bunch of fun.

** We did cell counts and nitrogen status on the yeast cultures every shift, plus monitoring them for sulphide production. They were used to pitch a ferment once they exceeded 10^8 cells / ml. The O2 culture got to count about 12 hours before the aerated culture, they were inoculated with two small (600 litre) cultures of the same yeast which had shown similar growth rates.


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## Dave70 (10/11/17)

Thanks LC.
I'm not fancy enough for growth targets as yet, we're only talking a Christmas keg stuffing APA, 2L x 200g of LDME and US05.
All the same, if I can do it right, much appreciated.


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## Dan Pratt (11/11/17)

lets not complicate this.

yes you can add O2 to the wort but don't waste it on continuous.

just make your starter and give it a whirl every hour and it will cultivate for the beer you are planning.


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## Lionman (13/11/17)

I give my starters a squirt of O2 before chucking it on the stir plate. Not sure if it helps significantly but I figured it should help at least a bit.


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## mtb (13/11/17)

Lyrebird_Cycles said:


> it improved performance** but it chewed through a size G oxygen bottle per day



If only there were some sort of invention, which produced practically infinite amounts of oxygen at the cost of only electricity.


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## Lyrebird_Cycles (13/11/17)

There is, it's called pressure swing adsorption, I was actively looking to trial a PSA based O2 generator for this purpose before I left.

Funny thing was the winery in question already had a huge FLOXAL nitrogen generator. I was never able to get an answer from Air Liquide on whether it could be modified to capture the waste O2.


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## manticle (13/11/17)

I think mtb might have been referring to just that.


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## Adr_0 (14/11/17)

manticle said:


> I think mtb might have been referring to just that.


I thought he was referring to LC's hydrolysis probe...


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## Dave70 (14/11/17)

mtb said:


> If only there were some sort of invention, which produced practically infinite amounts of oxygen at the cost of only electricity.



TA DAAA!!

http://www.instructables.com/id/Separate-Hydrogen-and-Oxygen-from-Water-Through-El/


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## BrockHops (14/11/17)

So I've been following the discussions on O2 production/use and thinking about harnessing O2 from sources other than a cylinder that I have to buy.

Now please, by all means feel free to give it to me if I'm barking up the wrong tree, but here's my thought;

When in use, Sodium Percarbonate releases O2..
What if I filled up my cleaned FV with the required amount of Perc. and water, place lid on, hook up silicon tubing in the "kitten port" of the lid ( out of the liquid of course).
So in my head(not the most reliable Vessel) the resultant O2 production travels through the tubing and aerates your Yeast/Wort for FREE!

Happy to be educated if I'm way off the mark.

Doctor Brock.


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## Dave70 (14/11/17)

BrockHops said:


> So I've been following the discussions on O2 production/use and thinking about harnessing O2 from sources other than a cylinder that I have to buy.
> 
> Now please, by all means feel free to give it to me if I'm barking up the wrong tree, but here's my thought;
> 
> ...



Interesting.
Now then, I have absolutely zero knowledge of how much O2 is released for a given weight of sodium perc, or for that matter, how much pressure it would take to stall the reaction, or how much head of pressure is in a 6mm tube at the bottom of a fermenter, _but_ I'm guessing when one of the smarty pants chemistry literate brewers chimes in it will be one of those deals where it comes unstuck on an economic level - i.e. - you'd have to dissolve a 20kg bag of 2 Na2CO3 to aerate your wort.


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## mtb (14/11/17)

Adr_0 said:


> I thought he was referring to LC's hydrolysis probe...


That I was.


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## Lyrebird_Cycles (14/11/17)

The diversion was deliberate.


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## Lyrebird_Cycles (14/11/17)

Dave70 said:


> Interesting.
> Now then, I have absolutely zero knowledge of how much O2 is released for a given weight of sodium perc, or for that matter, how much pressure it would take to stall the reaction, or how much head of pressure is in a 6mm tube at the bottom of a fermenter, _but_ I'm guessing when one of the smarty pants chemistry literate brewers chimes in it will be one of those deals where it comes unstuck on an economic level - i.e. - you'd have to dissolve a 20kg bag of 2 Na2CO3 to aerate your wort.



Not really, it's a sesquiperhydrate so it releases 1.5 oxygen atoms per percarbonate moeity which has an MW of 156. That comes out to 24 / 156 parts oxygen or one part in 6.5. If you wanted to produce say 10mg/l for 30 litres wort you'd need about 2 g of percarbonate.

To accelerate the breakdown to oxygen you can add a source of catalase: a strip of potato peel is convenient. (see https://aussiehomebrewer.com/threads/potato-peel-oxygen-generator.95313/ . Manganese dioxide (the black stuff in a standard battery) will also work. BTW someone in that thread also suggested using percarbonate as a peroxide source but since I have high strength peroxide available every day I didn't need to.

The trouble I see with the method proposed by Brockhops is that the bubble size will be so large you'll get very poor utilisation. The obvious correction for that would be using a sinter but that creates a further complications in that you have to take the operating pressure into account when calculating the hold up volume in the reaction vessel and tubing.

The trick I used in the thread referenced was to enclose the thing in silicone tubing which is highly permeable to oxygen. Bubble size was still larger than optimal however.


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## Dave70 (14/11/17)

Suppose you could use a corny for the 'pressure vessel' with a length of tube plumed onto a disconnect with a 2 micron diffusion stone on the end. 
At worst it can only not work.


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## Lyrebird_Cycles (14/11/17)

In the other thread someone suggested using a PET soft drink bottle. If you used a 1.25 litre bottle and a couple of metres of hose you'd have a void volume around 1.3 litres which is around 2 g of oxygen at STP. Assume 90% loss in the injection process (see post #695 in this thread) so to add 0.3 g to the fermenter you need to put in 3 g, that's a total of 5g O2 to generate, so you'll need about 32 g of percarbonate and a small amount of catalyst.


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## Dave70 (14/11/17)

Careful how you go LC. Potential sales for your hydrolysis probe may be evaporating in a cloud of cheaply generated 2 Na2CO3..


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## Lyrebird_Cycles (14/11/17)

Nah, there will always be cheap ghetto methods of adding O2 but they all lack precision. 

In the above example, you won't know if you are getting 5% or 20% utilisation instead of the 10% predicted, so the actual O2 delivered to the wort could be double what you wanted or it could be half.


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## BrockHops (14/11/17)

Cheers for the discussion guys, you never know the outcome, good or bad by not throwing out an idea.
I knew one of our scholarly types would be able to explain some more.
Thanks,
Brock


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## pirateagenda (3/12/17)

I have seen it done for a larger batch with an aquarium oxygen pump and stone. don't see why that wouldn't work.


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## wide eyed and legless (3/12/17)

Been reading a lot about this lately going to give it a go on my next brew, can't say I have been over the moon with oxygenating the wort as others have, will give priming the starter with o2 and compare it to the results I have had with giving the wort some o2.


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