Why Aerate When Ptiching Viable Quantities?

[Filby]

Hi

Ive been mulling this over in my head and also talking to a few professional brewers about it and coming to the same conclusion. You dont need to aerate wort prior to pitching if you are pitching a viable quantity of dry yeast (ie an 11g sachet of dry yeast). Obviously if you dont have the correct quantity then you need the yeast to breed in the oxygenated wort to get their numbers up.
I only see aeration as another potential point of infection, so why do people bother? I have never aerated and never had a problem with my yeast going nuts and achieving FG in 3-4 days.


Cheers

Fil

edit: Danstar agrees:

Do I need to aerate the wort before pitching dry yeast?

No, there is no need to aerate the wort but it does not harm the yeast either. During its aerobic production, dry yeast accumulates sufficient amounts of unsaturated fatty acids and sterols to produce enough biomass in the first stage of fermentation. The only reason to aerate the wort when using wet yeast is to provide the yeast with oxygen so that it can produce sterols and unsaturated fatty acids which are important parts of the cell membrane and therefore essential for biomass production.

 

[felten]

If you're only using dry yeast, sure.

Aeration won't hurt them though, as for an infection point I guess it depends how you are doing it, and what you are (or aren't) sticking into your beer to aerate it.

 

[Bribie G]

I generally use recycled yeast and always aerate because, not having a yeast lab (yet ) I don't know what actual cell count I have, and the wort contains no oxygen anyway - and I guess that would be the case whatever cooling method I used. Commercial breweries certainly aerate because their yeast is drawn off from the bottom of their conical fermenters and although it is claimed that many smaller breweries such as the Wig and Pen use the likes of S-04, I expect that only gets repitched as an "insurance policy" after several consecutive brews.
Traditionally, wort was aerated by cooling it in "coolships" with a large volume exposed to the air, and later by refrigerated "dribbling" devices like this old photo from the Allsopp Lager Brewery 100 years ago:

 

[stux]

Doesnt the aerobic stage provide some esters, possibly desirable ones

 

[Thirsty Boy]

With dried, no real need - but really, no harm either. A bit of oxygen is pretty much only ever going to help. If you have persistent infection problems though, I guess its one way to minimise a potential point for them to occur.

If you are using dried yeast and you know for sure that it is a fresh pack that has been well kept and the number of cells in it is appropriate for the wort you are pitching it into and you plan to properly re-hydrate the yeast before pitching and you are sure you have no plans to re-harvest the yeast for use in another batch....

Then sure, there is no need aerate

Not so sure about any of those things? Then bunging in a bit of oxygen will go a long way to eliminating any of the problems they could cause.

 

[Newbee(r)]

If you are using dried yeast and you know for sure that it is a fresh pack that has been well kept and the number of cells in it is appropriate for the wort you are pitching it into and you plan to properly re-hydrate the yeast before pitching and you are sure you have no plans to re-harvest the yeast for use in another batch....

Then sure, there is no need aerate

Not so sure about any of those things? Then bunging in a bit of oxygen will go a long way to eliminating any of the problems they could cause.

+1

Having had a few stuck fermentations, aeration has made a measurable difference. If I don't aerate before pitching on average I have a 30-40% chance of it getting stuck.