Nottingham yeast does not require aration

[Wheelspin]

In the Danstar data sheet on their Nottingham yeast, they state quite categorically that this yeast does not require aeration.

Section 4, last paragraph.

Being a newby I was under the distinct impression that all yeasts would benefit from a good wort aeration.

What gives here ? Is this specific to this yeast strain only ?

 

[geer537]

My understanding is it is more specific to Dry Yeast- Check this response on Danstar's site

 

[badhabit]

I have seen this info and this type thread before. Danstar wants to make the point that there is enough yeast to get the job done in their packet. The real world is that yeast multiplies in the presence of 02. Having more 02 is better than having less if you want the yeast to grow....you decide. If you are using a Danstar product and getting stuck at 1.020 you would have very good reason to areate if you are not already doing so.

 

[daksin]

Oxygen in beer wort is utilized by yeast to generate sterols they can incorporate into their cell membranes when reproducing. Dried yeast have already undergone this process and are not significantly helped by the addition of oxygen.

If you are using liquid yeast, or harvested yeast after pitching dry, your yeast will need oxygen.

 

[WoodlandBrew]

In a typical fermentation yeast cells grow to five times the initial population. Is there enough sterol reserves to support all if these divisions? Wouldn't adding oxygen only help in the event that the sterol reserves were depleted?

 

[Calder]

In a typical fermentation yeast cells grow to five times the initial population. Is there enough sterol reserves to support all if these divisions? Wouldn't adding oxygen only help in the event that the sterol reserves were depleted?

Supposedly less than a drop of olive oil contains sufficient sterols for yeast to use in a 5 gallon batch. I think the number was 1/10th of a drop.

I think there is plenty mixed in with the yeast.

 

[Wheelspin]

Here's very interesting thing I also got from the Danstar web site RE aerating procedure. It can be found in ARTICLES under AIR VS OXYGIN

"The best time to introduce oxygen into the wort is on the second day of the fermentation. The yeast need it the most at this time. Some commercial breweries are beginning to adopt this technique"

I've been told never to introduce any more oxygen after initial aeration as this will lead to oxidation in the wort.

Who would have thought. Any comments ??

 

[WoodlandBrew]

Supposedly less than a drop of olive oil contains sufficient sterols for yeast to use in a 5 gallon batch. I think the number was 1/10th of a drop.

I think there is plenty mixed in with the yeast.

I've never quite understood the science behind using olive oil as a substitute for sterols. Yeast synthesize sterols from fatty acids and oxygen. Assuming that somehow oil can be substituted one for one with sterols , one tenth of a drop seems low. The sterols make up 1% of the yeast mass at the start on fermentation (The Science of Brewing - Fix page 95 in the "Initial Stages" section) At the end of fermentation, in order to have healthy yeast, the mass will also need to be 1%. Typical yeast mass is about 1kg at the end of fermentation. So that makes 10 grams of sterols. 10 g of oil is about 10ml or 100 drops.

Here's very interesting thing I also got from the Danstar web site RE aerating procedure. It can be found in ARTICLES under AIR VS OXYGIN

"The best time to introduce oxygen into the wort is on the second day of the fermentation. The yeast need it the most at this time. Some commercial breweries are beginning to adopt this technique"

I've been told never to introduce any more oxygen after initial aeration as this will lead to oxidation in the wort.

Who would have thought. Any comments ??

I agree, that does sound strange. Dr. Fix also writes in his book (on the same page previously mentioned) that oxygen is absorbed within hours of the start of fermentation. I can see how it might follow that after the oxygen is absorbed you would want to add more oxygen to aid in sterol production, but I think this would be at the detriment to the beer. After fermentation has begun the yeast have produced a number of products that can be oxidized. As we all know, the oxidization of these produces off flavors that are quite undesirable.