Author Topic: PURE O2 vs. NATURAL AIR AERATION  (Read 4765 times)

Offline majorvices

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Re: PURE O2 vs. NATURAL AIR AERATION
« Reply #45 on: January 22, 2010, 11:01:16 AM »
Interesting idea. Thanksfully our favorite brewing scientist has a DO meter. Maybe he'll find out for us.  ;)
Keith Y.
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Re: PURE O2 vs. NATURAL AIR AERATION
« Reply #46 on: January 22, 2010, 11:32:06 AM »
Interesting idea. Thanksfully our favorite brewing scientist has a DO meter. Maybe he'll find out for us.  ;)

Thaks  :).  I have thought of that method as well and will put it on my list of things to try.

One reason why shaking is so effective is that the amount of oxygen you actually need to get to ~8 ppm in the wort only a small part of what is actually available in the head space. This is also why I have been proposing a fairly simple and foolproof procedure for a large starter:

- boil 2.5 and let cool 2 gal of water
- boil and let cool .5 – 1 gal of wort (you may combine this with the water before boiling)
- sanitize a carboy and add water and wort.
- close carboy top and shake extensively to dissolve as much head space O2 as possible.
- add yeast and let ferment it out.
- decant spent starter beer and rack “production” wort on top of the yeast. Aerate wort and resuspend the yeast.

I haven’t tried this yet but the idea is that you have a large volume of diluted wort which is not only less stressful on the yeast but it is also able to hold much more O2 per yeast cell and thus there should either be more growth or healthier, i.e. sterol richer, yeast cells. I don’t know how it would compare to a stirred starter though.

Kai


Offline ndcube

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Re: PURE O2 vs. NATURAL AIR AERATION
« Reply #47 on: January 22, 2010, 11:58:53 AM »
So basically your suggesting making a starter that has an OG in the 1.010 ballpark?

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Re: PURE O2 vs. NATURAL AIR AERATION
« Reply #48 on: January 22, 2010, 12:04:57 PM »
So basically your suggesting making a starter that has an OG in the 1.010 ballpark?

pretty much. But not primarily for the low gravity but for the larger amount of O2 that will be available for the yeast. I do the same but constantly pump air though that starter.

Kai

Offline ndcube

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Re: PURE O2 vs. NATURAL AIR AERATION
« Reply #49 on: January 22, 2010, 03:08:42 PM »
The low gravity won't make the yeast want to floc out w/o a stir plate?

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Re: PURE O2 vs. NATURAL AIR AERATION
« Reply #50 on: January 22, 2010, 03:32:01 PM »
The low gravity won't make the yeast want to floc out w/o a stir plate?

Yes, it will still flocculate once most of the sugars are consumed. I guess this technique would be more for brewers who lack a stir plate.

Kai

Offline dean

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Re: PURE O2 vs. NATURAL AIR AERATION
« Reply #51 on: January 22, 2010, 05:28:47 PM »
New Belgium's olive oil experiment was such an effort. Other efforts include oxygenation of the yeast before it is pitched into the wort.

Kai

This is a Great thread!!  I got thinking about this the other night contemplating what I might have done difrerently with a particular batch of beer that I made and that I really liked (one Keith helped me with about a year and a half ago)... the only thing I can think of that I haven't tried is using olive oil, which I may have used at that time.  The beer in particular had more esters.  I don't know if that is worth noting or not because I didn't take good notes back then.  I sure liked that batch of beer though... it was awesome, and I'll continue to try recreating it even if I never do, it was that good.


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Re: PURE O2 vs. NATURAL AIR AERATION
« Reply #52 on: January 24, 2010, 08:42:11 AM »
Here is quite big drawback of the DO meter I bought: The probe doesn't fit into the carboy neck :(. Oh well, I was moving to buckets anyway.

Unlike with a pH meter, a DO meter cannot be used to test small samples since it consumes the O2 in the sample and the act of pulling the sample and moving the DO probe around in it may actually aerate it further.

Kai

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Re: PURE O2 vs. NATURAL AIR AERATION
« Reply #53 on: January 25, 2010, 07:34:36 AM »
I brewed again this weekend and got to play around with oxygenation again.

But I hit a slight snafu. The yeast was propagated in a carboy and I was feeling too lazy to move it to a flask after it had settled. The idea was that I would be able to count cells and don’t have to weigh the slurry to find out how much yeast I pitched. But after racking half the wort onto the yeast I realized that it was not un-flocculating as quickly as I hoped and that I would also not be able to take a wort stability test before and after aeration. I started doing the latter to asses how much contamination various form of aeration gets into the wort. And then the DO (dissolved oxygen)  meter probe didn’t fit into the carboy opening and I had to scratch the intend of evaluating shaking as a form of aeration.

Since I really wanted to test the DO level I moved the beer to a bucket and oxygenated with an O2 wand. Here is what I got for oxygenating the 10 l of 4 C (40 F, a bit colder than I wanted it to be) 16 Plato wort:

initial: 3.4 ppm
after 20s: 4.3 ppm
after another 20s: 5.6 ppm
Then I noticed a crack in the bottom of the racking cane that I build the O2 wand from and I had to cut it to fix the problem. The crack allowed O2 to bypass the sintered stone.
after fixing that and another 35s: 8.1 ppm

Looks like the oxygenation rate improved once I fixed the crack and more O2 was forced though the sintered stone

The ~20 hrs later I added the remaining 8 l and oxygenated again. I added the wort in 2 stages since I suspected that I didn’t have enough yeast to pitch the full wort volume.

At that point the yeast was already active but I didn’t have Kraeusen yet. The rather low pitching temp must have contributed to that.

The initial O2 reading was 2.4 ppm which might be quite imprecise since I’ll have to re-check the zero-calibration.

30s O2: 4.1 ppm
+30s O2: 4.9 ppm
+60s O2: 7.5 ppm
+60s O2: 12.2 ppm

This result is much different from what I got before where it took only 60s of pure O2 to get more than 20 ppm of DO. I wonder if the active yeast had anything to do with that. Future experiments will tell. I’ll also have to check if the time between oxygenating and testing makes a big difference. It might make a difference if there are still many O2 bubbles in suspension.

Kai






Offline goybar

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Re: PURE O2 vs. NATURAL AIR AERATION
« Reply #54 on: January 29, 2010, 08:59:23 AM »
Wouldn't shaking/splashing the wort in the fermentor affect head retention?
 
Or are the head forming proteins created during/after fermentation?

Chris