Bavarian Cold Fermentation

How are you fermenting?

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Ancient Abbey
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Re: Bavarian Cold Fermentation

Postby Ancient Abbey » Wed May 24, 2017 9:24 am

I'd second the mash profile. It is possible to step up too quickly and denature enzymes.
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Smellyglove
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Re: Bavarian Cold Fermentation

Postby Smellyglove » Wed May 24, 2017 10:11 am

Hmm. What can be done with the mash schedule? I use a Herms which bumps temp in the mash with about 1.25C/min. I don't ever overshoot the herms to get quicker temp-raises, as I don't want to expose the enzymes to to much heat. The enzymes never see a higher temperature than the set-temp.

Im running one pack of yeast on a stir plate, I don't have a microscope so I target (with a yeast calculator) about 2.5-3bn cells/ml.

Don't have a DO meter either, but running a 0.5 micron stone for about 90-120 seconds at about 0.5L/min.

They have both been fermenting at a stable 9C (temp controlled fridge) since 12th of may.

I'm not having any troubles wih ale yeasts, so I guess maybe it's a fermentation/yeast issue.
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Weizenberg
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Re: Bavarian Cold Fermentation

Postby Weizenberg » Wed May 24, 2017 11:58 am

Smellyglove wrote:Don't have a DO meter either, but running a 0.5 micron stone for about 90-120 seconds at about 0.5L/min.


This is most likely your problem. I found it impossible to estimate oxygen levels. If you want to do this properly, investing in a DO meter is de-rigeur. If you really can't, then maybe you can borrow one so you get a feel and correct timings.
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Ancient Abbey
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Re: Bavarian Cold Fermentation

Postby Ancient Abbey » Wed May 24, 2017 4:51 pm

Smellyglove wrote:I'm not having any troubles wih ale yeasts, so I guess maybe it's a fermentation/yeast issue.

By 'one pack', do you mean dry yeast, or a smack pack? You were using 940/833, no?

Have you tried one using the yeast cake from a previous batch instead? I tend toward 50% cells coming from slurry and 50% coming from the stir plate.
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Weizenberg
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Re: Bavarian Cold Fermentation

Postby Weizenberg » Wed May 24, 2017 5:06 pm

Abbey nails fermentation regularly. I'd heed his advice any day ;)

What I didn't mention is that I propagate in 3 steps -- that may well have a substantially different effect on the vitality of the yeast. Mine goes pretty fast after pitch. That 50/50 suggestion is indeed something worth trying befor yous splash out on a DO meter. In my case, the DO meter made a huge difference when I got it about 4-5 years ago. But that's specific to me and my process. Your mileage may vary.
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Techbrau
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Re: Bavarian Cold Fermentation

Postby Techbrau » Wed May 24, 2017 5:51 pm

I gotta wonder if your fridge is colder than you think it is. Have you verified that your temp controller probe is calibrated? If you're actually fermenting at say 7c, I can see your yeast stalling at 1.018.

For what it's worth, nowadays I pitch at 7-8c, ferment at 9c, and let rise to 12c when I rack to spund. Primary takes about 6 days, spunding another 4-5, then I drop to 2.5c to clear it. Ready to drink at about 20-25 days old.
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Weizenberg
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Re: Bavarian Cold Fermentation

Postby Weizenberg » Wed May 24, 2017 6:14 pm

Ah, see, this is where we still differ. With calibrated thermometer (they are calibrated every year), pitch 5, ferment 7-8, transfer 5, then it dissapears for 8 weeks. Everyone will eventually settle on their own method. A stopped fermentation at 1.018 SG would make a pretty authentic Czech brew though... for what it's worth :D
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Smellyglove
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Re: Bavarian Cold Fermentation

Postby Smellyglove » Sun May 28, 2017 7:39 am

I checked the temp-probe against a thermapen and its still calibrated. I've had better luck with doing a 68c instead of a 72c, so maybe I'll just go back to that. But its weird since everybody are able to pull off the 72 step and still make it ferment to target sg.
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Re: Bavarian Cold Fermentation

Postby Big Monk » Sun May 28, 2017 8:20 am

Smellyglove wrote:I checked the temp-probe against a thermapen and its still calibrated. I've had better luck with doing a 68c instead of a 72c, so maybe I'll just go back to that. But its weird since everybody are able to pull off the 72 step and still make it ferment to target sg.


May seem like a silly question but was the Thermapen calibrated? I'm sure it was and that's below the level of detail for your post but...

Also, if you are having attenuation issues and you feel you can rule out factors like temperature issues, Yeast, etc. changing the last rest at 72 °C isn't going to help there.

Recently Bryan ran some tests using multiple β rests to determine percentage of extract gained (on the way to 100% conversion) at various temperatures. These initial experiments showed only about 3% of the extract coming from the α rest (72 °F). If you think your attenuation issues are mash related, I'd look to the β rest(s) and play around there.
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Re: Bavarian Cold Fermentation

Postby Smellyglove » Sun May 28, 2017 8:55 am

Big Monk wrote:
Smellyglove wrote:I checked the temp-probe against a thermapen and its still calibrated. I've had better luck with doing a 68c instead of a 72c, so maybe I'll just go back to that. But its weird since everybody are able to pull off the 72 step and still make it ferment to target sg.


May seem like a silly question but was the Thermapen calibrated? I'm sure it was and that's below the level of detail for your post but...

Also, if you are having attenuation issues and you feel you can rule out factors like temperature issues, Yeast, etc. changing the last rest at 72 °C isn't going to help there.

Recently Bryan ran some tests using multiple β rests to determine percentage of extract gained (on the way to 100% conversion) at various temperatures. These initial experiments showed only about 3% of the extract coming from the α rest (72 °F). If you think your attenuation issues are mash related, I'd look to the β rest(s) and play around there.



Yes, that's my reference thermometer, so that's the only one I do calibrate once in a while, and calibrate all the other sensors to that one.

So, to sum up.

All my ales are hitting expected FG, but I don't do a 72C step for those, except for the Hefe, which i have been doing a few times, that one ends up one point or two higher, but it's "ok". Ales are be stepped past 72C, but not holding it there.

I'm getting 2 SG-points "extra" when I do a 72C, or, just when i pass it on my way to mashout. Everytime. I'f im 2pts low at sacc-rest at for instance 63 or 65, I know I'll be good by the time i pump to boil.

72C hold for 15-20 minutes ish, has always given med about a point or two extra on the FG, comparing to if I don't hold it.

All my sensors are calibrated, and ale-fermentation leaves me with is expected.

Yeast-handling. I use a bunch of fresh yeast off the stir plate. I decant it after about two or three days in the fridge (depending on which strain). I do pay attention so I don't pour out the most attenuative cells, which maybe hasn't flocced completely at that point.

I did a doppelbock, but that was with 3470, where I did a 68 instead of a 72, and it ended up at 26. OG was 1.078, 26 was pretty expected.

I oxygenate until it almost foams over with a 0.5 micron stone.

Low boil, so not too much maillardproducts in the boil.


The two beers in question are
#1: 2nd gen 940
#2: 1st gen 833

Good healthy dose of yeast into each,

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