K-97 Yeast

[A3k]

Hi fellas,

I put a brew down last week, and its just about finished in the fermenter. It was an attempt at a partial Koelsh. I had to stop allgrain as I moved into a unit, and my partial setup is pretty shite, so I only used 1.5kg grain.

Anyway, I used the k-97 dried German Ale yeast and went away for work. When I came back, the fermenter was at 26C and smelt like a wheat beer with a banana smell. It should be okay, just not what i was hoping for.

I'm considering reusing the yeast. Will reusing the yeast slurry at 18C result in a loss of the banana smell, or should I just get some more yeast?

Also, would K-97 work okay in a Coopers Pale Ale style beer? My CPA starter isnt taking off too well.

Cheers,
Al



The Koelsh recipe was:


Type: Partial Mash

Batch Size: 23.00 L

Ingredients

Amount Item Type % or IBU
1.50 kg Coopers Light Malt Extract (5.3 SRM) Extract 33.33 %
1.50 kg Coopers Wheat Malt Extract (6.5 SRM) Extract 33.33 %
1.00 kg Pilsner (Weyermann) (1.7 SRM) Grain 22.22 %
0.25 kg Cara-Pils/Dextrine (2.0 SRM) Grain 5.56 %
0.25 kg Melanoidin (Weyermann) (30.0 SRM) Grain 5.56 %
15.00 gm Northern Brewer [9.90 %] (60 min) Hops 15.3 IBU
28.30 gm Hallertauer [3.70 %] (30 min) Hops 8.3 IBU
20.00 gm Tettnang [4.10 %] (15 min) Hops 4.2 IBU
1 Pkgs SafAle German Ale (DCL Yeast #K-97) Yeast-Ale



Beer Profile

Est Original Gravity: 1.053 SG
Est Final Gravity: 1.014 SG
Estimated Alcohol by Vol: 5.15 %
Bitterness: 27.7 IBU
Est Color: 7.2

 

[peas_and_corn]

Firstly you're fermenting a little too warm- you should aim more around the 20C mark.

This is what Safale has to say about it-

This yeast produces a slight amount of the banana and clove characteristics, some sulfur. It is a clean fermenting yeast producing a cloudy beer. Excellent top cropper.

From that description I wouldn't describe it as a perfect yeast for a pale ale, but I don't see a huge reason not to.

 

[A3k]

Cheers Peas and corn,

i realise 26C is much too high, it got away from me when i was away from work for a few days.

do you know if using the yeast slurry from the previous batch will bring the undesired flavours caused by the high temperatures to the new batch if the temperature of the next is kept low.

maybe i'll just persist with coopers yeast.

Also is it worth cold conditioning the Koelsh or is it a lost cause

cheers
al

 

[peas_and_corn]

Off flavours cause by high temperatures are created during fermentation. I am not 100% on whether these chemicals would be also caught in the trub, maybe another person on the forum can patch that hole in my knowledge but I wouldn't worry about it if I were doing it.

With your Koelsch- give it a go, can't hurt! At worst you will find out that it isn't 100% and chuck it, or maybe it will turn out OK!

 

[DJR]

The extra esters (banana etc) won't be in the trub, so repitch to your heart's content. I'd aim for about 16c if using k-97 only in a Koelschy ale, i had pretty good results in a recent Alt with a 50/50 mix of K97 and US05 at about 18-20C as well, might be worth a shot.

Cold conditioning will let some of the esters mellow out a bit, but not a huge amount. Will make your Kolsch quite smooth/crisp/fresh after a bit of lagering when using a proper Kolsch/Alt yeast in my experience, haven't tried K97 by itself in a Kolsch so give it a go - you usually get the most benefit after about 1 to 2 weeks of CCing