Starter size doesn't matter

Listened to a talk by a researcher from White Labs last night at the San Diego QUAFF meeting. She talked about pitching yeast for high gravity ales (above about 1.090.) For one experiment, she did four starter sizes, from small to large, each one twice as large as the last. (I don't remember the smallest one but it was small.) This went into a ~1.090 wort. To my surprise, there was no significant difference in final gravity for any of the experiments.

Her conclusion was that aeration and yeast nutrition were far more important than starter size, and her research seemed to support this.

I'll try to email her to get more details on her experiment, but to me it was an unexpected conclusion. Cool that people are doing these experiments though.

Did she comment on the 1) the length of time it took each to get to the FG and 2) were there any distinct off-flavors from the smaller-starters that could have been due to stressed yeast?

Jersh said:

Did she comment on the 1) the length of time it took each to get to the FG and 2) were there any distinct off-flavors from the smaller-starters that could have been due to stressed yeast?

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This is the important question(s).

tamoore said:

This is the important question(s).

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+1 just because the yeast can ferment to that low doesn't mean they didn't throw a ton of extra crap into the mix?

+2 A single yeast cell would eventually ferment the beer out. The whole point is that reproduction causes side effects. Some is good, too much causes off flavors. Not that FG would change.

If the OP is relating accurately the test, the results and the conclusion (that aeration and yeast nutrition were far more important than starter size), then this deserves some consideration. If indeed this was a "researcher from White Labs", one would think that she would be aware of and concerned about issues like the "crap" produced by reproduction, yet she was most interested in attenuation. I know, I know... the importance of starters of abundant, healthy yeast is cherished dogma, sometimes seemingly unassailable by reason or evidence, but this isnt' the first time I've heard of industry professionals suggesting that "healthy" is much, much more important than "abundant". I'd like to see the credentials and details.

Was the speaker Neva Parker?

"Neva Parker has been with the White Labs family since 2002. She earned her bachelor's degree in microbiology from Gonzaga University in Spokane, WA. She became interested in beer while studying abroad in London when she attended the annual Campaign for Real Ale (CAMRA) festival. Neva manages laboratory operations and has been responsible for researching and developing new products and services, as well as speaking at several workshops and conferences, and publishing fermentation research. She is a member of the American Society of Brewing Chemists, Master Brewers Associate of the Americas, and AHA homebrew club of the year for a seven-year streak, the Quality Ale and Fermentation Fraternity (QUAFF). In her spare time, Neva enjoys spending time with her beer enthusiast husband, Glen, and her beautiful daughter, Ada (born in January of 2009). Her hobbies include cooking, eating, making up baby songs, brewing, organizing, and happy hour."

If she says that healthy is more important than cell count, I think it'd be safe to believe her. Considering that she is the laboratory head at white labs, it seems they believe her too.

Pilgarlic said:

If the OP is relating accurately the test, the results and the conclusion (that aeration and yeast nutrition were far more important than starter size), then this deserves some consideration.

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This is exactly what I would have expected from the test, though, so no further consideration needed. The issue with pitching rates has never been getting to FG, homebrewers severely underpitched for many, many years and reached FG. The issue is how it affects the flavor of the final beer. We all know that yeast health is paramount.

Like others above, I want to know if there were any significant flavor differences. Then my interest might be piqued.

It would sure seem to me that the researcher would have considered "how it affects the final beer" in concluding "that aeration and yeast nutrition were far more important than starter size". I'm hoping to hear more specifics from the OP. Maybe, because I'm newer to the hobby, I'm just more interested in questions than conclusions at this point (actually, I confess that I almost always find questions more interesting). In any event, I'm monitoring for further info.

Results from a similar test: http://seanterrill.com/2010/05/09/yeast-pitching-rate-results/

Again, both reached the same FG, but one took longer to do it and there were differences in the final beer.

Great study, Scimmia. Seems pretty conlusive, or as much as one study can be. It is also clearly corroborated by the convicted, extremely wide consensus among the apparently most knowledgeable posters here. I've emailed Neva Parker. Maybe I'll have a response.

Jersh said:

Did she comment on the 1) the length of time it took each to get to the FG and 2) were there any distinct off-flavors from the smaller-starters that could have been due to stressed yeast?

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Yes, and indeed that was the main thrust of her talk - that you should choose your pitching rate to determine what taste you wanted from metabolites rather than desired final gravity. Replicating yeast produce metabolites that people perceive as "yeasty" for example. I've emailed her for more details. (One of the problems of going to a talk at a homebrew club is that it can get a little noisy so I missed a few things.)

jacksonbrown said:

Like others above, I want to know if there were any significant flavor differences.

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From Neva's email:

Higher gravity generally means greater metabolic byproducts (fusels & esters)
Higher metabolic activity generally means greater flavor byproducts (esters, fusels)
Higher pitching rate generally means lower acetaldehyde, higher fusels
Higher oxygen at start generally means lower acetaldehyde, higher fusels & esters

(And lower pitching rates generally result in more metabolic activity in the beer.)

So I guess it's all in what you are going for. (And the original post probably should have read: Starter size doesn't matter when it comes to total attenuation.)

Well from my experience what takes 7-10 days with a new yeast pack takes 2-3 days when tossed on that same yeast strain's cake.

The only difference I see being cell count.

billvon said:

From Neva's email:

Higher gravity generally means greater metabolic byproducts (fusels & esters)
Higher metabolic activity generally means greater flavor byproducts (esters, fusels)
Higher pitching rate generally means lower acetaldehyde, higher fusels
Higher oxygen at start generally means lower acetaldehyde, higher fusels & esters

(And lower pitching rates generally result in more metabolic activity in the beer.).....

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Most of this makes perfect sense, except:
higher metabolism = lower pitch rates = higher fusels & esters. Check!

BUT THEN higher pitch rates = low acetal & higher fusels?

Something does not quite synch up here. or it could just be me!

BUT THEN higher pitch rates = low acetal & higher fusels?

Something does not quite synch up here. or it could just be me!

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It looks like everything leads to higher fusels, which doesn't seem right. Unless they are all stripped back out in conditioning. But the email seems to agree that higher pitching leads to lower reproduction, which lowers flavor byproducts (esters).

I kinda figured it was just a simple typo. Everything else fits.

billvon said:

(And the original post probably should have read: Starter size doesn't matter when it comes to total attenuation.)

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Agreed. This is hardly an epiphany, as healthy yeast should reproduce and eventually reach full attenuation. The post could also be restated as: Starter size with healthy yeast does not affect total attenuation but does have significant impact upon the taste profile of the beer.

Neva Parker took the time to send a thoughtful email. Edited version follows. Let me know if you want data and methodology, I'll email:

Hi Bob -
Just got a chance to read through the postings, very interesting stuff. It looks like Bill posted the notes from my talk there (and just to clarify, the higher fusels thing was a typo!).

Most importantly, it's not an issue of attenuation, as someone mentioned. It's a matter of the flavor byproducts produced during fermentation. If you want more yeast-derived flavors (the esters, etc), then slightly under-pitching (of course making sure to oxygenate well and provide enough nutrients) will get you there. If you're looking for cleaner flavors, promoting less yeast growth is your goal. In the end, I think we all need to remember that this isn't a black and white process. The metabolic process is a really complicated machine, and all of the pathways are still not completely understood. Changes in different brewing parameters will always have an effect on the final beer, because it's always going to affect how the yeast react. Yeast are living organisms, and there are so many ways to manipulate them to do what you want or need, as long as you give them adequate amounts of the essentials - sugar, lipids, amino acids.

Cheers,

Neva Parker
Head of Laboratory Operations
White Labs, Inc.
Pure Yeast and Fermentation

Duffer said:

BUT THEN higher pitch rates = low acetal & higher fusels?

Something does not quite synch up here. or it could just be me!

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It can. Higher pitch rates usually mean more active fermentation, which means more heat. If you aren't actively controlling temperature, this means hotter fermentation which will mean higher fusels.

Or she could have meant lower (acetaldehyde, higher fusels), i.e. there are fewer high order fusels.