Get into O2 guys, if you're serious about nicer beer

[technobabble66]

From the internets:
"Catalase breaks down and destroys hydrogen peroxide in two steps. The first step involves the catalase removing and binding one oxygen atom and releasing the rest of the hydrogen peroxide molecule as water. The second step is the catalase breaking down another hydrogen peroxide molecule by releasing oxygen gas and water."
So yes, it breaks down the H2O2 in a way that prevents the O• radical from interacting with other components of the wort or yeast.

The million dollar question actually is whether the H2O2 reacts *significantly* with components of the wort to oxidise them *while waiting* to be decomposed by the catalase.
The couple of studies i've seen indicate most H2O2 should be mainly neutralised within 20-30mins, and completed within 1 hr. So it's a small window for anything detrimental to occur.
However, the window is definitely there and it seems unknown as to whether anything significant would occur between the 0.0005L of H2O2 and the ~20L of wort. Given the time frame and the tiny quantity, i'm inclined to assume it'll be minimal. Real testing and comparisons are needed to go from here.

 

[Jack of all biers]

The million dollar question actually is whether the H2O2 reacts *significantly* with components of the wort to oxidise them *while waiting* to be decomposed by the catalase.
The couple of studies i've seen indicate most H2O2 should be mainly neutralised within 20-30mins, and completed within 1 hr. So it's a small window for anything detrimental to occur.
However, the window is definitely there and it seems unknown as to whether anything significant would occur between the 0.0005L of H2O2 and the ~20L of wort. Given the time frame and the tiny quantity, i'm inclined to assume it'll be minimal. Real testing and comparisons are needed to go from here.

And it is for this reason I have included the painful process (for me) of only testing a bottle of each every two weeks. Imagine if the H2O2 beer oxidises after 2 months! That's going to hurt when the majority of 25L tastes like cardboard. But in the name of science, I'm willing to take that risk :drinks:

 

[Jack of all biers]

I'm in adelaide and have an O2 set up. Happy to get involved.

Hi Killer Brew. You able to do a comparison yourself between O2 and H2O2 or only willing to assist with supplying an O2 squirt to someone else's brew (ie me)?

 

[MHB]

Been doing a bit of reading up on peroxide and yeast - I wont be putting any into beer any time soon!

The enzyme Catalase is a part of the yeasts defence against naturally occurring peroxides that can harm the yeast, like any enzyme it has an optimum temperature (~37oC) and an optimum pH 6.8-7.5. Both of these conditions are well outside the brewing conditions where anyone using peroxide would be working, like any other enzyme it wont work very well outside its optimum range.
Some of the enzyme might be excreted into the environment (the wort) but most is found in either the cell membrane or in the cell mitochondria where it can defend vital cell functions.

As someone mentioned above, natural selection is a very important and harsh master, yeast (and most other cells) have evolved Catalase to defend themselves from harm done by naturally occurring peroxides. The amount of peroxide that yeast could be expected to encounter is in the range of 1-0.1ppb, call it 0.5ppb give or take. we are talking about adding 10ppm (10,000ppb) or so. there is no conceivable way yeast will be equipped to handle 20,000 times as much as it evolved to cope with.

There is a wealth of difference between peroxide and oxygen.
Similarities are always suspect, but lets see if this puts it in perspective; we want some Chloride in our wort lets say 50ppm is a good thing, if we added 50ppm of Chlorine in the form of bleach we wouldn't expect the same result, in fact we can be fairly sure the yeast would die.
We also know peroxide is a steriliser, it reacts with most any organic chemical like a free radical ion (think O-), the breakdown product of the reaction is water and Oxygen. The result of adding bleach to chalk will leave chloride ions in solution, like the reaction with peroxide it isn't the end product that scares me it the process that takes us there that does all the harm.

There at threads on avoiding HSA, reducing O2 in packaging... All of them have in common the benefits of reducing Oxidative harm to the beer, after a lot of study I think adding peroxide is the exact opposite and will have all the negative effects associated with Oxygen harm.

I notice some commentary on the response on other fora, where the "Experts" jumped in and rained on the parade - from all I can gather very sensibly.

Mark

 

[Dave70]

Sooo..
Did we settle on a 5 or 2 micron diffuser?

 

[MHB]

Nah you need a 3.5um stone - someone should start making them.
M

 

[technobabble66]

I believe 2 was meant to be fine. I assume the 5 you mention should've been 0.5 micron?

 

[drsmurto]

I've only very briefly skimmed the discussion on H2O2.

A few points from a scientist whose research area involves H2O2 and O2 in juice/wine; similar situation holds with wort/beer.

Firstly, the reason why O2 is used and not H2O2 is that O2 can't react with organic compounds. This is what is called 'spin forbidden' and is a very fundamental principle of chemistry relating to the configuration of the electrons in the atom. It first reacts with transition metal ions to produce the superoxide radical which can then react with organic compounds. Yeast can mop up the oxygen very rapidly and in a medium that contains only trace amounts of reactive transition metals in the required oxidation state, it will do so before much, if any damage is caused by oxygen via the superoxide radical. We have measured the speed in which yeast uses up all the oxygen in juice and it is very fast, in the order of minutes. We can also measure oxidation markers to see what chemical effects are being caused by O2 introduction and the result is negligible. Our oxygen sensors measure down to ppb levels of oxygen.

This is not the case with hydrogen peroxide, it is very capable of reacting with organic compounds or just about anything it comes into contact with. This is not a selective process, you can't expect yeast to protect the wort from H2O2 as it cannot prevent every single molecule of H2O2 from colliding with other molecules in the wort. Adding an incredibly powerful oxidiser to your wort is not a particularly well thought out method of adding O2.

In regards to double dropping as a method of introducing oxygen into wort after fermentation has commenced, this is not something I have seen data on. I have, however, seen published data in a winemaking setting during what is referred to as a pumpover. This is done when a red wine is actively fermenting and is done to wet the cap (floating grape skins/seeds) to increase extraction of colour/tannin etc. To get any decent amount of oxygen in, a range of in-line devices were required to effectively draw oxygen into the liquid as it was passing through the pump, think spargers/venturis or even just 'cracking the fitting'. The physical act of splashing wine back into the ferment is very ineffective as the liquid isn't picking up any oxygen and the splashing impact is mitigated by the layer of CO2 protecting the wine.

 

[technobabble66]

Thank you for your explanation, DrS. Namely in the way O2 gas is cleaved and then processed/mopped up by the yeast
I'd have to concede that O2 gas seems a (much) superior way to add oxygenation.

... We have measured the speed in which yeast uses up all the oxygen in juice and it is very fast, in the order of minutes. We can also measure oxidation markers to see what chemical effects are being caused by O2 introduction and the result is negligible. Our oxygen sensors measure down to ppb levels of oxygen.
...

Just out of interest, have you done these tests for H2O2 additions?
I'm simply curious as to how significant that oxidation of wort by the peroxide is, considering the small amount used (~0.5mL in ~21L) and the variety of other elements of potential oxidation in our homebrewing process.
Call me stubborn or persistent, but I'm merely wondering whether there could still be use of the peroxide as an option secondary to something better like O2 gas, given its simplicity of use & setup.
Also whether the oxidation consequences would be enough to be detectable.
Clearly the O2 gas is best/better practice, but I'd be keen to more conclusively know that the peroxide is not a viable ghetto option that'll still provide some benefits for minimal costs and flaws.

Edit: posted before adding half the text [emoji52]

Edit 2: if the only concern is oxidation of wort, could peroxide still be an easy option for oxygenation of starters, where the supernatant/liquid is decanted off and discarded?

 

[rude]

Might change my sanitiser as I use Hydrogen Peroxide

Usually hit the fermenter with it just before I pitch

 

[drsmurto]

Sulfite/sulfur dioxide is added to wine for 2 reasons. To protect the wine from microbial spoilage, which in combination with the low pH of wine provides protection (sulfite exists in 3 forms depending on the pH - sulfur dioxide, bisulfite, sulfite). The other reason is it is an anti-oxidant. It is there to protect the wine from oxygen. The vast majority of wine is bottled with no yeast present at all so a defence against O2 is needed. As I mentioned previously, O2 get's converted to the superoxide radical via transition metals. This is converted to hydrogen peroxide. At this point, sulfite reacts with it to remove it from the wine. If there is no sulfite present, the superoxide is further reduced by another transition metal to an even more reactive molecule, the hydroxide radical. This, for example, reacts with ethanol to produce acetaldehyde. The last step in this reaction is known as the 'Fenton Reaction'.

So if you are adding hydrogen peroxide to wort you have skipped one reduction step, also known as the rate limiting step, and provided the system with a highly reactive molecule that otherwise would not exist in any substantial quantity if you had added oxygen. We don't measure H2O2 directly, we use the reduction in sulfite to measure the amount of hydrogen peroxide produced and the kinetics of the reaction. There is plenty of research in this area and it is ongoing.

I can't stress this enough. H2O2 is a very powerful oxidant, it will react with any molecule it comes in to contact with. I use it to 'digest' wine (it breaks apart the complex molecules and within hours, red wine looks like the palest white wine), clean glassware. In combination with concentrated sulfuric acid, it's used to etch glass. It is used to power rockets. It's one of those chemicals you treat with the utmost respect, particularly if you are using 30% or greater concentrations.

Thank you for your explanation, DrS. Namely in the way O2 gas is cleaved and then processed/mopped up by the yeast
I'd have to concede that O2 gas seems a (much) superior way to add oxygenation.

Just out of interest, have you done these tests for H2O2 additions?
I'm simply curious as to how significant that oxidation of wort by the peroxide is, considering the small amount used (~0.5mL in ~21L) and the variety of other elements of potential oxidation in our homebrewing process.
Call me stubborn or persistent, but I'm merely wondering whether there could still be use of the peroxide as an option secondary to something better like O2 gas, given its simplicity of use & setup.
Also whether the oxidation consequences would be enough to be detectable.
Clearly the O2 gas is best/better practice, but I'd be keen to more conclusively know that the peroxide is not a viable ghetto option that'll still provide some benefits for minimal costs and flaws.

Edit: posted before adding half the text [emoji52]

Edit 2: if the only concern is oxidation of wort, could peroxide still be an easy option for oxygenation of starters, where the supernatant/liquid is decanted off and discarded?

 

[nosco]

I'll get to the point of my extended question that may not have an answer. Does yeast use o2 more slowly at colder temps?

So if I have slowly chilled a beer to lager temps, say 4c, and then want re-use the yeast slurry for another ferment after racking off the beer. So as not to shock the yeast I keep it at 4c and re pitch it into some oxygenated 4c wort (is that necessary to pitch @4c?) and let it free rise to ferment temp. Will the o2 come out of solution before the yeast has woken up enough to use the o2? o2 later at a higher temp? Also considering that the o2 will dissolve (?) more easily in colder wort?

Edit: If its used in minutes as you say Dr S is it still the case at lager temps. Free rising to ferment temp could take hours (in this heat at least).

 

[MHB]

nosco - there are a couple of interesting points in there.
Basically as a rule in chemistry and biology everything happen slower colder and faster warmer, with the solubility of the O2 being the obvious exception.

I would be very tempted to add nutrients, including Oxygen, at or close to the temperature you are planning on brewing at. For lager this is generally going to be in the 8-12oC range. yeast hates sudden changes in temperature and everything we can do to keep yeast healthy and happy is a good option.
I would only oxygenate a starter in the presence of other nutrients (wort) and when the yeast is at or near pitching temperatures, same if pitching the yeast slurry directly into the wort.

You would be way better off lagering and storing yeast at 0oC (give or take one).

 

[nosco]

Thanks MHB. Good to know Im thinking along the right lines. Hopefully my brewing will follow suit :unsure: . My current practice is to pitch and then oxygenate. It makes sense to me but I have improved my o2 setup so I have a few options now.

Ill go to 4c to get the yeast and then 0c for the beer. I dont want to risk freezing the yeast.

 

[nosco]

So to recap on that question. Subtle changes (up or down) in temp are good for yeast but there is no real reason to pitch at 4c. Its maybe better to let the decanted yeast free rise to about 7c, pitch into 7c wort and then oxygenate. That's what Im going with.

Edit: Hopefully my fridge, equipment, kids, wife and lack of sleep will let me achieve that

 

[Killer Brew]

Hi Killer Brew. You able to do a comparison yourself between O2 and H2O2 or only willing to assist with supplying an O2 squirt to someone else's brew (ie me)?

Happy to help out with the O2. Might leave the experimentation to those who have paved the way.

 

[Jack of all biers]

Happy to help out with the O2. Might leave the experimentation to those who have paved the way.

Thanks. I will crack on with the experiment with the Ale as per my earlier post and see if the oxidation hits taste thresholds by the time it's all finished. If that experiment shows no discernible oxidation flavours, then and only then would I be keen to conduct an O2 H2O2 comparison. If that happens, I'll PM you to see if you are still keen to help out (maybe months from now).

DrSmurto clarified exactly what I suspected would be likely with the breakdown of H2O2 to H2O and O. Whilst, I know some oxidation would be likely, I am still keen to do this comparison to see just how much oxidation occurs and how long it takes to show in the beer. Call it curiosity of a potential ghetto method or what ever you will, but it's going to cost me a few bucks and time doing something I enjoy.

EDIT - If the H2O2 beer gets oxidised quick then I can always use it as slug/snail bait in a bowl or two in the garden. They love it. Too DEATH. Haaaaa, haa, haaaa, haa.

2nd EDIT - I don't like slugs okay. Drowning them in beer seems like the most humane way to me. :drinks:

 

[Stouter]

Some great discussion going on here, good too see, sensational effort.
When just asked, I explained to the wife about how there are blokes on his forum that are scientists, leaders of various industries, and philosophers discussing the merits of putting air in beer. Makes little old, average joe me look pretty special oxygenating my wort hey!

 

[Lionman]

Just ordered a reg and stone off eBay. Will oxygenate my next batch with Tradeflame O2 from Bunnings.

 

[sp0rk]

Finally biting the bullet and enquiring about a Coregas O2 cylinder, if my local supplier doesn't sting me too much I'll try and pick the gear up this week

*edit*
Nope, they don't do Coregas swap and go like Bunnings does and I'm not paying rental
Looks like I'll get a Brewman setup