Aerated yeast vs aerated wort

[spamman1368]

So I've been wondering, and I apologize if this has been on here before, if you make a yeast starter on a stir plate a day before the brew day, do you have to aerate your wort? Or will the oxygen in the slurry from the stir plate carry it? For example, say I make a 2 liter slurry and add it to 10 gallons of wort; is that 2 liters of highly oxygenated, very strong and healthy yeast goin to be enough or do I still have to drop my oxygenating stone in the wort when racking?

 

[Pratzie]

Yeast use oxygen very very quickly so yes, u should still aerate ur wort before u pitch as well.

Plus, think of it this way, ur adding O2 to a small 1-2 liter solution (starter). Even if the yeast didn't use ANY of that oxygen, it still wouldn't be enough to reach the 8+ppm u'd want when u add that to a 5 gallon batch.

 

[spamman1368]

Ok that's what I thought but wanted to check. Thanks!

 

[spamman1368]

Ok, now here's something I just read that caused me to ask this question:

http://www.danstaryeast.com/articles/aeration-and-starter-versus-wort

Granted, this is dry yeast, but regardless they're talking about aerating your starter and not your wort if the alcohol level isn't super high. Since I'm just doing light pilsners, wheats, etc can I do this? If so I'd imagine it would be better than directly aerating the wort for stability and flavor purposes. Thoughts?

 

[afr0byte]

You should still aerate your wort. It's not going to hurt anything, and is likely to help (even if you're using dry yeast).

 

[peterj]

Ok, now here's something I just read that caused me to ask this question:

http://www.danstaryeast.com/articles/aeration-and-starter-versus-wort

Granted, this is dry yeast, but regardless they're talking about aerating your starter and not your wort if the alcohol level isn't super high. Since I'm just doing light pilsners, wheats, etc can I do this? If so I'd imagine it would be better than directly aerating the wort for stability and flavor purposes. Thoughts?

No, they are saying if the alcohol level is 3-5% then you can just pitch their dry yeast without aerating because it contains enough lipids for the cells to reproduce enough to produce a healthy fermentation. If you make a starter with dry yeast, you are losing that high lipid level because you are causing the cells to divide. They explained how they get the high lipid levels in their yeast and how you can't achieve those levels with a starter no matter how much you aerate. That's why you shouldn't make a starter with dry yeast.

"Your starter culture will have a much higher level of sugar. You will produce some cell mass but mostly alcohol and CO2 no matter how much air you add by stirrer or bubbles"

So if you really don't want to aerate then you should pitch dry yeast, no starter. But like afr0byte said, you should still aerate because it won't hurt anything. It will probably help and it's really not that hard of a step. I've never heard of any stability or flavor issues from aerating, unless you're pumping a ridiculous amount of pure O2 in there.

At the end that one guy was saying that some commercial breweries are just aerating their starters, but who knows how big their starters are. And they're probably still getting aeration through whirlpooling and agitation, they're probably just not using O2. It's hard to compare commercial practices to homebrew practices because the size differences can be very important.