Interesting Article on Wort Aeration

springer said:

again with proper pitching no large scale growth is needed

When 100 g active dried yeast is used to inoculate 100 litres of wort, a yeast density of 5–10 million
cells per millilitre is achieved.

optimum yeast count is 10 million per milliliter correct? so if you have between 5 and 10 the yeast only need to reproduce once not the 6 to 8 times as been said. I dont call one generation large scale reproduction

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If you're referring to pitching rate then it's actually around 1 million cells of viable yeast, for every milliliter of wort, for every degree Plato. If you pitch such that you only need one generation, you over-pitched. The dry yeast is given enough reservoirs to get 3-4 generations (for a reason).

The takeaway for me on all this is that, for most beers, there is no "need" to buy a pump and stone. If you already have one, however, use it. But don't have a cow over those that don't use one. RDWHAHB!

For me, I use mostly hydrated dry ale yeast. Mostly American IPAs. If I splash rack, shake a little, 8 hours later the yeast are always happy. We all repeat what works, and this is one way. Seems like these arguments always have too much emotional attachment on what we ourselves personally own and/or do. Good beer can come from different techniques or products.

I can see where pure O2 and a stone would be another cool toy, but most don't "need" to buy it.

Rich

I noticed in the Wyeast presentation on page 22 it shows a chart comparing dissolved oxygen vs. cell growth in 5 flasks. It appears to me that the diff between 9ppm and 26ppm isn't all that much (1.5 doublings vs. 1.7 doublings). Also, the pages following show that they made 2 beers with DO levels at 6,14,28 and on page 25 it gives a brief summary of the results:


Unfortunately it does not give the specifics of the test or the data collected. The question that keeps coming up in my mind is how much does the ppm of dissolved oxygen really matter in the end result. I have not been convinced (yet) that 8ppm will make a noticeably inferior beer to 26ppm.

mmonacel said:

Am I missing something? I'm pretty new so that's probably the case, but is there some significant benefit to using O2 aerating pumps and stones and other such fancy equipment? I figured as long as the wort gets aerated enough that the yeast are able to do their job and effectively go from your planned OG to your planned FG, you've succeeded.

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+1 Could someone explain the importance of getting a high oxygen concentration? Seems to me like a lot of brewers have been getting perfectly good results just by letting the wort splash for a long time. I know yeast grows better with high O2 levels, but it seems like if getting proper yeast growth is a problem for you it'd be better just to pitch more yeast

You could start with the wyeast powerpoint referenced repeatedly in this thread.

Some people are trying to do better than "perfectly good".

remilard said:

You could start with the wyeast powerpoint referenced repeatedly in this thread.

Some people are trying to do better than "perfectly good".

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According to the wyeast powerpoint, 9ppm DO correlates to 1.5 yeast doublings, and 26ppm correlates to 1.7 yeast doublings. Is that enough to make a noticeable difference in the end product? The powerpoint does not give enough information to answer that question IMHO. Please read my post a couple up.

-TH- said:

According to the wyeast powerpoint, 9ppm DO correlates to 1.5 yeast doublings, and 26ppm correlates to 1.7 yeast doublings. Is that enough to make a noticeable difference in the end product? The powerpoint does not give enough information to answer that question IMHO. Please read my post a couple up.

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Did you read the entire powerpoint? You don't consider significant evidence of qualitative differences demonstrated in blind tasting to be information?

Shaking the fermentor has never failed me in the past. I don't see a reason to stop now. Whenever we upgrade to larger batches I still plan on aerating the wort... logically it seems like it would help since it's necessary for the chemical reactions to take place. I dunno. Stick to what I know, I guess.

remilard said:

Did you read the entire powerpoint? You don't consider significant evidence of qualitative differences demonstrated in blind tasting to be information?

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I did look at every page but I suppose I could have missed something. I do not however consider this:

to be significant evidence. I don't know how many tasters there were - 3? 30? 300? I don't know how many tasters preferred one over the other - 55%? 95%? All it says is that tasters preferred the pale @28ppm and the amber @6ppm. That's not enough to convince me in either direction.