Triple Aeration

[Wolfy]

Information in the 'Yeast' book suggests that I have not been providing enough oxygen in the wort to satisfy the yeast's needs.
The only aeration I've done has been to splash the wort into the fermentor and then shake it around, so most likely the O2 levels have been around 3-5ppm which is well below the 8-10ppm required.

The book also mentioned that the yeast consumes all the oxygen in the wort in the first 30mins, in "The Compleat MeadMaker" the author actually aerates after the yeast is added, which made me consider how I could provide more O2 without having the expense of using pure oxygen or the additional cleaning/sanitising/setup of using additional equipment like an air-stone and air-pump.

BribieG's 'Double Dropping' was a good step, but if the yeast use up the oxygen in the wort in the first 30mis and it takes about that to drain the kettle through the CFC and cool the wort, I figured I could put that time to better use.

By collecting an amount of cooled wort in the flask used to make the yeast-starter, I spent the 20mins it took to drain the kettle shaking the crap out of it:

While that may only ever get to around 8ppm of O2 and there is only a small amount of wort, if the yeast consume the oxygen while I add more for 20mins, it would seem logical that they'd be able to use up that O2 to make the lipids and sterols they use to reproduce.

Add the usual splash-into-fermentor, and then shake the crap out of it:

Follow that the next day with Double Dropping:

And I'll either end up with oxidized beer, or will have given the yeast an adequate supply of Oxygen in three different ways.
Given the book suggests that "Too much oxygen is rarely a problem" I'm hopeful that the yeast will be happier and the beer will be fine.

 

[felten]

It says they use the available o2 up in 30m, but I think it also says its pointless to add more o2 until they've divided at least once, which was after the 12-16hr mark. That extra aeration probably won't hurt, you'd probably have to be hitting it with pure o2 for long periods to do that.

 

[ekul]

what about adding olive oil? Seems very possible for the homebrewer although probably wouldn't suit all styles because the paper says that ester production is increased slightly. Its an interesting read if nothing else.

 

[Bribie G]

The Yeast book leaves the olive oil question open, but doesn't dismiss it. Another useful device could be one of these: which I'll be getting with my next order - I'm hoping it will slide onto the end of a bottling cane so, during dropping, it can sit down into the lower fermenter without spraying all over the brewery

 

[ekul]

Another thing i've been thinking of is pressurisng the cube with oxygen and then letting it sit for a little while.

How I was going to do this was attach a schrader valve and inline filter to a cube lid and keep it for pump up cubes. I has an air compressor so i could just pump up the cube with as much air as it can hold. The extra pressure and the motion of carrying the cube to the fermenting fridge should oxygenate the wort fairly well. There's also an oxy in the shed, but i'm not sure how full the bottle is. I think it would be easier to over oxygenate using pure o2 instead of air, although i'm not even sure that is a real thing.

I like the idea of oxygenating like this over shaking because when i shake the cube up i always get heaps of froth, and sometimes it spills over the edge of the fermenter.

 

[Thirsty Boy]

A trick i use to get the most oxygen i can into the wort without using pure O2 is simply to make the wort very cold. Cold liquids absorb a lot more gas than do warm liquids.

So i put my NC cube in the fridge for a day or three and get it down to a nice 5C or so (which if you care about it also makes a lot more cold break form and drop, to be left behind if you want) then while its still cold i tip with as much splashing as possible about a third of the cube into my fermenter, then lid back onto cube and it gets teh snot shaken out of it for a coupe of minutes. Then the rest is splashed into the frementer.

I wait till the wort is a few degrees below my target primary ferment temp, and pitch the yeast. The wort is going to be saturated and mabe even a little supersaturated with O2 at that point becuse it will be warming up past its equalibrium point and off gassing the O2 thats already dissolved. Yeast going in a little colder than normal means they get a bit of extra O2 right at the start and i get to cold pitch which is my preference.