Kolsch yeast to 88% attenuation?

I recently began recording my apparent attenuation, and I'm getting 88% with White Labs Kolsch yeast. White Labs says between 72% and 78% on average.

I used 7.5 lbs 2 row and 7.5 lbs Pilsen. Mashed at 148 degrees F. Water came out to about 1.5 qts per pound of grain once I got the temperature right. Mashed for 60 minutes, batched sparged with 3 batches.

I fermented a little low, around 64 degrees F during active fermentation...dropped to around 62 degrees F once it settled down. My OG was 1.036 which fermented down to 1.004 in a week. 36 - 4 = 32, 32/36 = 88%...is this typical?

If I'm not mistaken, I believe that alcohol is less dense than water, which would mean that 100% attenuation would end up below 1.000, which in turn means your attenuation is lower than the 88% you're calculating.

I can't tell you what SG you'd get from 100% attenuation (though there's probably a simple calculation for that), but that might explain why your numbers seem high. Again, I'm not an expert or even an amateur on this stuff, so I reserve the right to be wrong once somebody who's actually well-informed pipes in.

88% sounds right to me, esp with a low mash temp, low OG & no specialty malts.

FatDragon said:

I can't tell you what SG you'd get from 100% attenuation (though there's probably a simple calculation for that), but that might explain why your numbers seem high.

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while 100% actual attenuation is below 1.000, apparent attenuation means 100% is 1.000. the #s are fine

A healthy yeast culture will continue to eat until it runs out of sugars that it can digest or reaches an ethanol level where the cells become dehydrated and die from the inability to move nutrients and metabolic waste products through their cell walls.

Mashing at 148F results in a highly-fermentable wort with an approximate sugar profile of:

Monosaccharide: 10%
Disaccharide: 61%
Trisaccharide: 9%
Dextrins: 20%


Your gravity readings in degrees Plato are:

Original Extact (OE) = 9P (1.036 S.G.)
Apparent Extract (AE) = 1P (1.004 S.G.)
Apparent Attenuation = (9 - 1) / 9 = 88.9%

However, apparent extract and apparent attenuation do not take into account that alcohol is lighter than water. The values that we need to calculate are real extract and real attenuation.

Real Extract (RE) = 0.1808 x OE + 0.8192 x AE

RE = 0.1808 x 9 + 0.8192 x 1 ~= 2.45


Real Attenuation (RA) = 1 - (RE / OE) x 100

RA = 1 - (2.45 / 9) x 100 = 72.8%

In essence, you have 27.2% of the converted starch remaining in solution, which is not out of line. Most brewing strains cannot ferment dextrins. However, your wort was only 20% dextrin when you pitched your yeast culture. Most brewing strains readily ferment monosaccharides (simple sugars such as glucose) and disaccharides (composed of two monosaccharide molecules bound together with a glycosidic bond); therefore, the attribute that really differentiates most brewing strains with respect to attenuation is their ability to ferment trisaccharides (composed of three monosaccharide molecules bound together with glycosidic bonds). The predominant trisaccharide in wort is maltotriose. Most lager (Saccharomyces pastorianus) strains readily ferment maltotriose. However, ale strains from the Sacchormyces cerevisiae species differ in their ability to break the bonds that hold the three glucose molecules together in maltotriose.* I would suspect that ale strains that are selected for making Kolsch can ferment maltotriose to an extent, as the ability to ferment maltotriose determines the "crispness" of a beer.


[*] Not all ale yeast strains are members of the Saccharomyces cerevisiae species. The ale strains used to ferment authentic German-style wheat beer belong to a species known as Torulaspora delbrueckii (a.k.a Saccharomyces delbrueckii).

EarlyAmateurZymurgist said:

A healthy yeast culture will continue to eat until it runs out of sugars that it can digest or reaches an ethanol level where the cells become dehydrated and die from the inability to move nutrients and metabolic waste products through their cell walls.

Mashing at 148F results in a highly-fermentable wort with an approximate sugar profile of:

Monosaccharide: 10%
Disaccharide: 61%
Trisaccharide: 9%
Dextrins: 20%

Your gravity readings in degrees Plato are:

Original Extact (OE) = 9P (1.036 S.G.)
Apparent Extract (AE) = 1P (1.004 S.G.)
Apparent Attenuation = (9 - 1) / 9 = 88.9%

However, apparent extract and apparent attenuation do not take into account that alcohol is lighter than water. The values that we need to calculate are real extract and real attenuation.

Real Extract (RE) = 0.1808 x OE + 0.8192 x AE

RE = 0.1808 x 9 + 0.8192 x 1 ~= 2.45

Real Attenuation (RA) = 1 - (RE / OE) x 100

RA = 1 - (2.45 / 9) x 100 = 72.8%

In essence, you have 27.2% of the converted starch remaining in solution, which is not out of line. Most brewing strains cannot ferment dextrins. However, your wort was only 20% dextrin when you pitched your yeast culture. Most brewing strains readily ferment monosaccharides (simple sugars such as glucose) and disaccharides (composed of two monosaccharide molecules bound together with a glycosidic bond); therefore, the attribute that really differentiates most brewing strains with respect to attenuation is their ability to ferment trisaccharides (composed of three monosaccharide molecules bound together with glycosidic bonds). The predominant trisaccharide in wort is maltotriose. Most lager (Saccharomyces pastorianus) strains readily ferment maltotriose. However, ale strains from the Sacchormyces cerevisiae species differ in their ability to break the bonds that hold the three glucose molecules together in maltotriose.* I would suspect that ale strains that are selected for making Kolsch can ferment maltotriose to an extent, as the ability to ferment maltotriose determines the "crispness" of a beer.

[*] Not all ale yeast strains are members of the Saccharomyces cerevisiae species. The ale strains used to ferment authentic German-style wheat beer belong to a species known as Torulaspora delbrueckii (a.k.a Saccharomyces delbrueckii).

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You're slipping...you forgot to cite Fix this time.

afr0byte said:

You're slipping...you forgot to cite Fix this time.

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Do you have anything to add to the discussion, Adam?

Edit - deleted

EarlyAmateurZymurgist said:

Do you have anything to add to the discussion, Adam?

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Not in this case, nope.

EarlyAmateurZymurgist, how did you determine the approximate sugar profile of my wort?

ziggy13 said:

EarlyAmateurZymurgist, how did you determine the approximate sugar profile of my wort?

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The values came out of Principles of Brewing Science.

I've had that book for a couple months and haven't read it yet...looks like it's next on my list.

Sent from my MB886 using Home Brew mobile app

EarlyAmateurZymurgist... thanks for posting those calculations. You answered a similar question I had on my latest in-progress Kolsch using Wyeast 2565 that has a similar profile to the one mentioned by the original poster.

I mashed a little cool (accident/my first attempt at all grain) at somewhere around 148F.

My OG was 1.044 and my SG after 9 days was 1.003.

Copying the calculations mentioned earlier that gets me to around 74% attenuation.

Nice to know that its all moving along as planned!

.