Jack of all biers said:
Peteru, your post got me wondering on the whole adding O2 via H2O2 method
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My only counter thought is that normally H2O2 (as linked by Bribie above) has stabilizers added to keep the H2O2 from decomposing in the container before you the consumer use it.
I have never even considered that there would be additional stabilisers added to the 6% v/v hydrogen peroxide I got from the chemist. My naive assumption was that it was 6% H2O2 and 94% H2O. As far as flavour goes, I have not detected anything that would stick out as contamination, but that does not mean it's not there. I actually happen to be allergic to nitrates, so if those are present I'll be ditching the use of this product. I'll try to contact the manufacturer to find out.
I performed a few (unscientific) experiments along the way to figure out if H2O2 could be used and if so, what's the simplest effective method. Given some of the extra information in this thread, I'll be looking at further tweaks, such as adding a catalyst, like a bit of yeast, to the chilled water. Although, what I do now seems to work pretty well.
My first point of investigation was to determine if adding H2O2 to a yeast starter on a stirplate would have detrimental effect on yeast and potentially kill it. It turned out that the yeast was fine, even when I added the undiluted 6% directly, drop by drop from a pipette. Next was a simple fermentation test. Two jars of wort, one with a few drops of H2O2 added, both inoculated with the same amount of yeast slurry and left to ferment side by side. The H2O2 jar performed "faster" and the resulting beer aroma and flavour was different from each jar. I can't say I had a preference for one or the other, they were just different. I never bothered carbonating or chilling either of those results, it was purely a quick sample evaluation at fermenting temperature to determine if the results were drinkable and comparable. The next test was a batch of Cooper's Stout can with recultured Cooper's Sparkling Ale yeast starter. This was followed by an American Pale Ale and an IPA that I kegged and keg hopped last night. Both of those had large San Diego Super Yeast starters. The stout is now a few weeks old and still pretty good - better than every other time I brewed it before, but I've also introduced fermentation temperature control recently, so temperature could be the big factor rather than additional O2. The APA is sensational, but I've never done that recipe, so can't compare. Same with the IPA recipe, it's first time for me.
So, I can conclude that adding H2O2 doesn't ruin the beer. I think it may improve it, but to be sure a proper controlled side-by-side comparison would be in order. I'm probably not going to get a chance to do that, because with Christmas and summer holidays/parties coming up, I'll be flat out trying to brew enough beer to keep friends and family hydrated. I would be very happy to see others have a go and report on their findings. My dilution rate has been around 1.4-1.5ml to one litre of water when using the 6% v/v hydrogen peroxide from the chemist. I add about 12-15l of this treated water to about 5 or 6l of liquid extract dissolved in warm water. My starters tend to be in the 1.5-2l range. Based on the maths that Mark posted, I could possibly increase that rate to 2-3ml per litre of water because the rest of the ingredients will dilute everything even further.
Anyway, I thought I'd share the idea and get a conversation going. Quite happy to hear arguments for and against as well as suggestions for improvements to the process.
