Ferment

[JoeyZR1]

I am on my 4th generation of ujssm. I havnt had any problems till now. The wash has that stinking sour puke smell this time, even more than usual. but my real question is about the yeast activating. on the previous batches it started the normal sizzling and then boom, rapid bubbling within 3 to 4 hours. this time after 12 hours there has not been any activity. my ph was at 5 and temp was at 92f. should i wait a little longer or just re pitch? I have been using baker's yeast yeilding a final fg of .990 to .998.at 12% abv. I just cant figure out it the 12% abv has stressed the yeast and killed it. any input would be appreciated.

[MitchyBourbon]

To answer your immediate question, the temp, 92°F is high. I would try to get that down to 85 if you can. 12 % abv is a little high. Doing multiple generations under these to conditions is going give even the hardiest of yeast a run for the money. I'm not an expert with ujssm, but thats my 2 cents worth.

I have a question or 2. Do you replace any of the spent grain and gunk on the bottom with fresh grain and fresh yeast between generations? At the beginning of each generation do you aerate? Or do you compensate by over pitching?

[JoeyZR1]

I added the backset in at 92f. And yes I replace spent corn every time. I keep a PID controlled temp at 85f. One thing that I did notice about the bakers yeast is on the package. It is recommended to start the yeast at 120f to 130f. I do not do that but I did one time on a different batch and the yeast exploded within 5 min. I haven't had to pitch any yeast as of now. The only thing that I haven't done is remove the old spent yeast. Wouldn't that be called Dunder? Do you think the spent yeast that has settled could be some of the problem? As of this morning there was some bubbling going on. But in the past it took off within a couple of hours.

[JoeyZR1]

Also I do a thorough areate every time.

[JoeyZR1]

I meant barm. In this recipe you don't repitch any yeast. My problem is it usually starts fermenting within a couple of hours. This time it didn't. I do know that the back set will lower the ph a good bit. I have been using oyster shells and I have used the 5.2 mash lock in buffer.

[raketemensch]

Check on it again in the morning. Yeast doesn't like to be scheduled, in my experience. I've been running UJ on the same yeast pitch for 9 months now, and it always has a mind of its own.

[JoeyZR1]

Yes, you are right. It has started back. Right now slowly but seems to be picking speed up now thanks

[JoeyZR1]

Check on it again in the morning. Yeast doesn't like to be scheduled, in my experience. I've been running UJ on the same yeast pitch for 9 months now, and it always has a mind of its own.

Did you read some of the previous posts? Do you ever remove any barm? The only thing I ever do is remove the spent corn. I keep the temp at 85f. I also aeriate after I add all my backset and usually a little fresh spring water to top off.

[raketemensch]

Yup, I read them all. I do the same as you, scoop, replace, aerate. I also melt my sugar in the backset and add a little 20-20-20 fertilizer or fermax for good measure, along with a small handful of oyster shells to buffer the ph.

[dieselduo]

After 5 or 6 gens I usually start over. Seems like it always has a ph crash no matter how much oyster shells I use

[JoeyZR1]

Yup, I read them all. I do the same as you, scoop, replace, aerate. I also melt my sugar in the backset and add a little 20-20-20 fertilizer or fermax for good measure, along with a small handful of oyster shells to buffer the ph.

Same here. Melt sugar in backset and use a wort chiller to get temps down below 95f. It seems some folks don't realize just how the backset changes the ph. The more gens you do the ph will get lower and lower. When I figure out more how to post I will show my ph meter it's the same as a municipal water plant would use. It cost $2500. So it's a handy device. Maybe someone one this forum could explain some of the function it is capable of doing I just use its basic features. From testing the contents of minerals in spring water to even fecal content and such. I thank you for your help also.

[raketemensch]

After 5 or 6 gens I usually start over. Seems like it always has a ph crash no matter how much oyster shells I use

I wonder if this is related to how much backset you add to each generation. I tend to stick around 15%.

[JoeyZR1]

I do 25%. The so called legal minimum got sour mash is 25%. I went by what Uncle Jesse posted. He uses 25% and some go as high as 50%. But UJ didn't recommend going over 25%.