Experience with A01 Imperial Yeast House

I can't say exactly what strain Imperial A01 is, but I would recommend not putting too much faith (or any, really) in the published attenuation ranges as a method to identify the strain. Every strain can attenuate both more and less than whatever numbers the yeast vendor puts on it. Fermentability of the wort is always key. (As you said...multiple factors.)

 

When a yeast vendor (e.g., White Labs) lists an attenuation range for a given yeast strain that is based upon a standard wort. In this manner you can compare and contrast the attenuation performance of the various yeast products from that specific yeast vendor.

Comparing attenuation numbers between vendors can be tricky since they may not be using the same standard wort for obtaining their attenuation values. You really should just compare within a single vendor’s product line.

What attenuation you achieve in your homebrew batch will depend on the fermentability of the wort you produced which needless to say will be different from a given yeast vendor’s standard wort.

Cheers!

 

White Labs lists 70-80 for WLP007. If they have a "standard wort," they must be completely incompetent at producing it or at measuring gravity.

 

Or yeast will provide varying fermentation performance over multiple batches?

 

Have you ever, in all your years of brewing, made the same recipe multiple times and had a range of 10 percentage points between the lowest and highest attenuation?

 

Below is discussion on how to utilize yeast vendor published attenuation values for yeast selection via White Labs:

“Most manufactures of brewers yeast list the attenuation ranges of their yeast strains. This can be very useful to a brewer in matching a yeast strain to a beer style. An example would be a brewer wishing to make an American-style Pale Ale. A yeast strain should be selected that will produce a dry finish, and allow for hop flavors to come through. A good choice would be a neutral yeast with an attenuation of 70-80%. If a brewer wants to make an English style mild ale, a yeast strain that does not attenuate as much would be desired. An attenuation range of 65-70% would be more appropriate. Would a yeast strain that attenuates to 80% taste bad in an English style mild ale? No, but the beer would not taste true to style.”

https://www.whitelabs.com/resources/attenuation-and-flocculation

Cheers!

P.S. Also some discussion about White Labs and standard wort: “Erik Fowler: …there is a standard wort recipe used to calculate attenuation.”

 

Where is this discussion?

 

Brewed with Omega's French Saison yeast, which claims 80-90%, and after measuring FG this weekend I ended up with 94.5% attenuation. Took the ABV a full percentage point up from the recipe prediction. I know it's diastaticus and that can lead to some fun fermentations, but just another data point that the suggested range is not always a great indicator.

@NorCalKid, no experience with A01. Sorry!