# NHC 2013: Kai Troester (Braukaiser.com) on stirplate starters



## slash22000 (13/8/13)

http://www.braukaiser.com/documents/Troester_NHC_2013_Step_Up_Your_Starter.pdf

This was very interesting. For those interested in the basic summary:

Constantly stirred starter showed vastly superior growth over unstirred starter (pretty sure we all know this one)

The greater access to oxygen the greater the growth, loose foil showed much better results than an airlocked starter, completely uncovered greater again (obvious contamination concerns)

*The faster the stirring, the greater the growth* - disproves conventional wisdom that "a small vortex is good enough", very significant improvement in growth between "small vortex" to "batshit insane wort cyclone"

*Higher gravity starter wort grows significantly LESS yeast* - the standard 1.040 wort is fine

Adding yeast nutrient to starter showed improved growth

Note that on http://www.yeastcalc.com/ you can use the "K.Troester" stir plate option. Apparently Jamil's yeast starter calculations (used by about every brewer on earth) were based on a non-stirred starter, while Troester's calculations are based on constant stirring and estimates much greater yeast growth.


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## SimoB (6/6/14)

Rebirth! 

So what is everyone using that has a stir plate??? K.Troester? Because I'm using a stirplate i'm thinking this is the winner?


It's true, AHB does have a lot of info once you start diggin'


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## DJ_L3ThAL (6/6/14)

Hmm I thought it was too good to be true, but thanks for this I can now use Troester's and use less steps/sized starters!!


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## OneEye (6/6/14)

On the phone now so can't check the site but doesn't Jamils calculator have a drop down box from which you can select stir plate? As well as intermittent shaking and others.


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## SimoB (6/6/14)

OneEye said:


> On the phone now so can't check the site but doesn't Jamils calculator have a drop down box from which you can select stir plate? As well as intermittent shaking and others.


Check this one out mate... 

Yeastcalc.com


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## DJ_L3ThAL (6/6/14)

here http://www.yeastcalc.co/yeast-pitch-rate-and-starter-calculator

The Chris White stir plate versus K. Troester stir plate calc yields *very* different results, K. Troester's being much more "optimistic"... any pros able to shed light on which is more accurate? I have previously been going conservatively using Chris White's....


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## Black n Tan (6/6/14)

Jamils Yeastcalc on MrMalty does include an option for choosing whether the starter is simple (not shaken or stirred), shaken or on a stirplate. It is generally recognised that a stir plate increases growth rate by 2-3 fold and Mr Malty and Beersmith use a factor of 2.67. Interestingly if you compare the simple vs stir plate option in MrMalty you will see if that all it does is divide the recommended starter volume by 2.67. Beersmith alternatively inputs the 2.67 factor directly into the growth rate part of the calculation, and Brad Smith has suggested that Jamil's method of applying this factor to the starter volume is not totally correct because growth rate and starter volume are not linear ie. if you increase the starter volume by 2.67 the growth does not increase by a factor of 2.67. h34r: Anyway food for thought.


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## SimoB (6/6/14)

here is a post from homebrewtalk 

_Use Kai's equation. Especially if you let it ferment to completion. His equations were produced from stirred starters instead of scaling still starters. It also more closely follows Ballings observation.

If you really want to dial in the measurement of cell growth without a microscope there are some calculations that can be done based on starting gravity, and final gravity as measured with both a refractometer and hydrometer. But for all practical purposes, Kai's equation will get you plenty close.

On my blog is a comparison of various calculators and actual growth of over 50 starters. These were all still starters, but it may be of interest.

http://woodlandbrew.blogspot.com/201...revisited.html_

_-----_

http://www.homebrewtalk.com/f163/yeastcalc-com-now-two-stir-plate-options-396992/


Im no expert but interesting read


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## Mardoo (6/6/14)

That was a great series. My anecdotal experience based solely on slurry volume produced - not actual cell counts - says Kai's estimates are closer. This of course doesn't account at all for the health if the yeast. Love to hear from a pro brewer though.


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