Oxygen in wort ?

[SuperBroo]

Hi All,

I am wondering why, we need to shake / splash as much as possiuble, a fresh cool wort before adding yeast.
I know its to add oxygen, but the wort is comprised of a lot of water, which is largely oxygen.

Is there a simple explanation for this, or is the oxygen actually completely removed while boiling ?

The same applies to using 'boiled then cooled' water, to remove / reduce oxygen for yeast storage etc etc, this doesnt really make sense. If it is water, its still largely oxygen, boiled or not.

Or am I way off the merk ?

Cheers,
Chris

[Bum]

Or am I way off the mark ?

Yeah, pretty much.

In regards to the second issue, which I'll address first as it requires less guessing on my part, you're not boiling for any reason connected to oxygen - you're boiling to kill any nasties in the water so you don't cause an infection. Simple as that, really.

The first issue raised, I'm pretty sure that boiling the wort does not simply turn all the water inside into liquid hydrogen (we'd be running much cleaner cars if it were that easy, I'm afraid. Equally, I'm pretty sure shaking our cubes isn't doing a great deal to change the molecular structure of the water within. I'd say we were just forcing some air into suspension in the liquid rather than changing the inherent nature of the water within. I should point out that I am looking at this from a very layman's perspective before I get shot down in flames by...er...no one in particular.

[warra48]

Bum is on the mark.

The oxygen in water is combined with hydrogen to form water (hence H²O). This oxygen is locked up and is not available as oxygen for the yeast to utilise in multiplying. Dissolved oxygen is normally driven off from water by boiling, but you are still left with the make up of water as H²O. What your yeast needs to multiply is more oxygen dissolved into the wort. That's why we aerate wort by various methods such as shaking, splashing, dropping it from a height into the fermenter, blowing air or oxygen through a pump etc.

Do your yeast a favour and give them the oxygen they need to do a good job on your beer. You'll love the improvement in the quality of your beer, compared to one where the yeast struggles.

Boiling water is, as Bum said, to sanitise it and kill off nasties.

[SuperBroo]

All good, thanks lads,

Yes, I always give the fermenter a good shake, so no probs there...

cheers...