Kolsch Wyeast 2565 High FG??

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Bobo1898

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Brewed a Kolsch two weeks ago. It's an all grain recipe that I've made before but with a new mashing method and on a new system.

When I've brewed this in the past, I mashed in at 148 for 60 minutes and lost a couple degrees over the course of an hour finishing at 146 (at the time, didn't have heat control over my mash tun). And did not mash out. Fermented at 66 (didn't have temp control and know this is high for the style). Reached terminal gravity 7 days at 1.010. Verified this several days later.

This go-around, I attempted to mash using the Hochkurz method. Mashed at 145 for 60 minutes and then 158 for 30 minutes. And I mashed out at 168 for 10 minutes. This was on an electric RIMS system so temp was constant. Now I have temp control for fermentation and set the fermenter to 60 but pitched yeast at 65 degrees. During fermentation, the internal temp reached 63 a day or two in, then made its way back down to 60. Then on day 8, I let the temp free rise to 65 over a couple days and it's been there for the last five days until this morning where it's dropping on its own---currently at 64. The current gravity is 1.014 after two weeks.

My OG in both cases was 1.056 (a bit high for the style).

The current batch has an attenuation of 74% whereas before, I got 81%.

I have an iSpindel in my fermenter so I can monitor what's going on and the gravity hasn't changed since day 10. And to be clear, the gravity numbers I'm giving you are from pulled samples with a traditional hydrometer. The fact the the beer is starting to drop in temp after free rising suggests to me that it's done. If this is the case, I'm a bit surprised my attenuation being 7 points lower. I made a proper starter on a stirplate that fermented out and was chilled and decanted, etc. The yeast packet was brand new according to the date on the package.

I will say the gravity sample that I tried yesterday did have some traces of diacytel and still had some bubbles in it. I left the sample alone for a couple hours while it degassed until it was still to verify the reading was accurate. With the activity, I'm sure the yeast still needs to clean up, but would that also mean I'll drop 4-5 points at this stage? My gut says probably not.

Was 145 too low? Did I not give it enough time at 145? Or is the lower fermentation temp a reason for the yeast to move slowly and this beer isn't done yet?

I've attached an image of the fermentation chart---plato/temperature. while the plato numbers on the chart would suggest I hit the accurate numbers, I should mention my iSpindel is not accurate (the weight is off) and, again, the numbers I measured are from my traditional hydrometer. Temp is green, plato is blue.


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RM-MN

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At 145 the alpha amylase probably wasn't doing anything and beta needs alpha to provide the broken ends of the starch molecules for it to work. As the temperature started to rise the alpha became active and broke the starch molecules so the beta could do its thing before the beta was denatured but the beta was struggling at that point. Then you heated the wort even more and both amylases became denatured. Most of the conversion probably happened as you heated the wort to the second step.
 
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Bobo1898

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Thanks for the response @RM-MN !

So it sounds like you're saying 145 was too low, which is obviously something I was asking about.

What could I have done differently (within this method)? Bump my beta rest a few degrees? Less time in beta? Hochkurz recommends the beta rest for 30 minutes, maybe 45, whereas I did 60 minutes.

Aside from breweries that have had success producing highly attenuated styles, using this method, I was under the impression that others have had success on the homebrew level as well.

I'm sure the beer will be fine, but probably too sweet for a Kolsch, and that's just sad and disappointing.
 

Holden Caulfield

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So it sounds like you're saying 145 was too low, which is obviously something I was asking about.
145 - 158 is a perfectly acceptable Hochkurz step mash schedule, and 60 mins is actually on the long side of the first step which should give you a decent level of fermentability for a Hochkurz, assuming your RIMS tube is working properly and not denaturing the enzymes. Also 1.014 is a very reasonable finished gravity for a beer that started at 1.056, so the sweetness level should be ok. If you want even more fermentability just raise the first step temperature to 148 and/or extend the length of the first step as well as lowering the second step temperature and extending its time.

There are a number of studies that have quantified the temperature impact of single infusion mashes and the level of attenuation, unfortunately I have never come across a study that tried to quantify the impact of different step mash temperatures and rest times.

The Hochkurz mash will give you more control over your wort profile, but it will take some experimentation to dial in the temperatures and times to achieve exactly what you want.
 

RM-MN

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Take a bit of time to read through this article and note the graph showing the "brewers window" paying attention to how the two enzymes work together and the temperature range for each enzyme.

 
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Bobo1898

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145 - 158 is a perfectly acceptable Hochkurz step mash schedule, and 60 mins is actually on the long side of the first step which should give you a decent level of fermentability for a Hochkurz, assuming your RIMS tube is working properly and not denaturing the enzymes.
Yeah, my pump is wide open and the temp probe is at the output of the element, so I wouldn't think it was denaturing the enzymes. At least, I hope it isn't.

Take a bit of time to read through this article and note the graph showing the "brewers window" paying attention to how the two enzymes work together and the temperature range for each enzyme.

Yep, will give this a read. Thanks for sharing.
 

hottpeper13

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I don't have a rims or herms but use boiling liquor for my steps and I always get ADF's in the low to mid 80's. If you're seeing crust on the bend of the rims coil you might be denaturing the enzymes.
 
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Bobo1898

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I don't have a rims or herms but use boiling liquor for my steps and I always get ADF's in the low to mid 80's. If you're seeing crust on the bend of the rims coil you might be denaturing the enzymes.
Yeah, prior to the RIMS, I used boiled additions or did decoctions for step mashes and I've also gotten the results you suggested. The kolsch had always hit low 80s, which was why I was confused as to where my terminal gravity sat. To answer your second point, I am not getting any crust on the element. Temp holds very steady. And I've never gotten a spike in temp on it. It hits its temp and runs very efficiently.
 
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