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Fermentation stuck


gmdiny

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Hello,

We have been having issues with stalled/slow fermentation of our Bourbon and Rye Whiskeys:

Here is the breakdown of the process with temps, ph values and SG and FG:

  1. Heat about 150 gallons of water to 190F, add corn.

  2. Add SebStarHTL

  3. Add SebStarFLO

  4. Let rest for 45mins to 1 hour

  5. Add rye and barley and water to bring down to 150F and top total volume to 900 gallons

  6. Add SebStarGL (glucoamylase) 

  7. Let rest for 1 hour

  8. Cool to 90F

  9. Pitch yeast

 

I use LD Carlson Dry Active Distillers Yeast

  1. Rehydrate in 90F Water

  2. Add 6 packets (453 grams ea.) to water

  3. Let sit for about an hour

  4. Than transfer into fermenter when wash is at 90F

Starting gravity is between 1.08 - 1.09

Starting PH is around 6.7 and works its way down to about 4.0 

PH of water going into the mash is 6.3. 

We aerate before the yeast is added using an air compressor. 

We do grain in fermentation, so nutrients should not be necessary? 

When everything was working the way it should, they would ferment dry in about 5 days. For the last 2 months, they will ferment hot and fast for about 2 days, then slowly trickly off and eventually stop completely. 

Any help at all would be much appreciated. If you have any questions please ask. I have no idea why they are stalling.


Thanks,
Greg

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It seems like they're stuck. There is little activity in the air lock bucket and when I check the sg it is generally the same, maybe slightly lower. Usually it seems to stall around 1.04-1.03

Edit: took a reading on the one that is having issues now; gravity is 1.05, 80f and 3.8ph. It has been at 1.05 the last 2 days. 

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The best way to get a stuck ferment going again is to make a big starter. Mix up your yeast and add a sizeable amount of mash to it, or add it to ~50 gallons of mash even, til it's churning away nicely, then add that to your stuck ferment. Our mashing procedures are very different, but if it works for the most part then I'm not sure why some are getting stuck and some aren't. Big differences are we add our corn before the cook up as opposed to adding it at 190, cook our rye in more the 160-170 range, barley at 145, and our gluco goes in at the very end right before the yeast.

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We had a run of these kind of problems during our first year. Likely what is happening is that you are not getting the right kind of conversion. Too many of your sugars are complex. The reason it ferments fast up front, is the yeast is eating all the simple sugars but as soon as it encounters more complex sugars it quits. So you need to review your fermentation temps and I notice you don't have any gypsum in your mix. That is required for the conversion and required for the health of the yeast. We also quit fermenting on the grain. Too much hassle and mess. And finally, we swapped out our yeast. Now we get quick clean ferments that dry out in about four days. We do use Fermaid K and we also add the gluco just before we add the yeast as kleclerc77 suggests. And finally, we tend to mash at lower temps - which seems to do a better job of creating simple sugars. 

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Mine - no. Although I do have controllable tanks, I don't use them. We do a wheat/barley mix often replacing the wheat with rye. I let the process run its course. It'll start slow for the first 10 or so hours, then it will wind up to about 40* - 42*C (too hot for most yeasts) and then gradually slow down. I distill when it hits room temp - usually the morning of day 4. Average take is about 8.5%.

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Sorry, to clarify I do add the corn during the cook up.  

Our fermenters are not temp controlled. The fermentation Temps vary based on the season. I dont have the file on hand now, but can update Monday. During the summer though they can reach 98 - 100F pretty easily, stall and when it cools it will kick back up again. During the fall, winter and spring is the optimal time for us to ferment. Usually I can atribute the stalling to the temps because they are high. 

I will start adding the gluco before the yeast.

Doesn't gypsum make the mash more acidic? 

Also thanks for the help. I've been with this company for 5 years and the fellow that had taught me left a while ago and this is the first time I'm running into issues that I'm completely stuck on. 

 

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I'd be worried about cooking my yeast. 900 gallons of grain in mash puts off and retains a lot of heat. It tracks with it only happening sometimes (summer?) as well. Can you go into the fermenter cooler to see what happens? 

If you can get it started again with a repitching of yeast like @kleclerc77says, and it finishes, you will know the conversion was good, and the problem is elsewhere. It might be hard to start again now that the ph is pretty low though.

Also, you use a different brand of enzyme than me, but you may want to ask them what Ph you should cook and rest at, I'd guess it should be lower, like 5-6 range. Maybe the ph of your grain/water has changed recently.

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The pH range for Sebstar GL is 2.8-5.5, at 6.7 you are quite a bit above where you need to be. Check and post your pHs at each setup of the process and be sure your pH meter is accurately calibrated. Similarly, SebFlo TL is denatured about 140 F, so adding at at 190 is probably not helping you much. Your volumes of cooking corn in 150 gal of water then topping up to 900 gal seems like a typo perhaps? 

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On 10/26/2020 at 5:42 PM, gmdiny said:

The one that was stuck is now going again after repitching. 

That is all very good to know about the enzymes. Found and printed the spec sheets as well to have handy. 

Thanks for all the help!

This is a business of times temperatures and PH. Everyone on this forum likely found yields increasing, product tasting better, and ferments progressing smoother as they've discovered the importance of being exact on times temps and PH.

 

At the end of the day, the most important thing is sanitation. Your times temps and PH mean nothing if the plant is infected. Good luck, and keep asking questions!

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  • 2 months later...

so, I've fought stalls, so I'll add that the things I've done since helped greatly.     Realize I only have 200 gallon mashes currently.  Spoke specifically to a chemist at Lallemand.

1. control pH below 6.0 using citric

2. lower temps for both re-hydration of yeast and temp of overall mash before adding yeast.   I hydrate at specified 96.8 degrees, but wait until mash is UNDER 90 before adding rehydrated yeast.   Continue to lower temps (I use a tubed crash cart) for the 15 mins I'm blending the two...usually putting in fermenter at 85 degrees or so.

3. Using yeast nutrients.   I add Distilavite, a Lallemand product.  The two types I add are GN, and HY.   

These 3 steps really helped eliminate stalls, and have sped up protocol to mostly get SG to 1.00 in 4-5 days.

I haven't had stalls in protocols where starting SG was under 1.65

Good luck...I know it's frustrating.

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  • 1 month later...
  • 4 months later...

my first guess would be incomplete gluco conversion, alpha has converted to complex sugars but gluco has only partially converted to simple sugars.

this is typically a temperature or pH issue

 

second guess, is Yeast, what Yeast are you using? some yeasts cannot survive the pH crash as ferment continues on. Recently had a friend dealing with this, same yeast he had been using for years at a different distillery just stalled out half way through ferment. changed out to DADY and it ferments just fine now.

you can side step this issue by adjusting the pH throughout the ferment, but this is a poor solution longterm.

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  • 2 weeks later...
On 1/4/2021 at 5:34 PM, LuckyGuy said:

so, I've fought stalls, so I'll add that the things I've done since helped greatly.     Realize I only have 200 gallon mashes currently.  Spoke specifically to a chemist at Lallemand.

1. control pH below 6.0 using citric

2. lower temps for both re-hydration of yeast and temp of overall mash before adding yeast.   I hydrate at specified 96.8 degrees, but wait until mash is UNDER 90 before adding rehydrated yeast.   Continue to lower temps (I use a tubed crash cart) for the 15 mins I'm blending the two...usually putting in fermenter at 85 degrees or so.

3. Using yeast nutrients.   I add Distilavite, a Lallemand product.  The two types I add are GN, and HY.   

These 3 steps really helped eliminate stalls, and have sped up protocol to mostly get SG to 1.00 in 4-5 days.

I haven't had stalls in protocols where starting SG was under 1.65

Good luck...I know it's frustrating.

Don’t adjust ph with citric 

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  • 3 weeks later...
On 7/7/2021 at 11:33 PM, SlickFloss said:

Don’t adjust ph with citric 

Either offer an alternative, or don't condemn.   I've used it for 3 years with very good results.   If you have an alternative that you've used, I would gladly listen.

 

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Malic is a better choice. 


http://docplayer.net/12103579-Artisan-distilling-a-guide-for-small-distilleries-kris-arvid-berglund-ph-d-electronic-edition-1-0-0.html
"

During primary fermentation and subsequent aging fruit acids are
decomposed through bacterial activity. In most cherry mashes the
decomposition of malic acid to lactic acid occurs without adversely
changing the mash. In the production of wine the conversion of the
“hard” malic acid into the “softer” lactic acid is in sometimes desired and
a secondary malo-lactic fermentation in undertaken intentionally. The
bacterial decomposition of citric acid leads to formation of lactic acid,
acetic acid, formic acid, and acetaldehyde which can be detrimental to
the mash and can appear in the resulting distillate. Decomposition
processes are associated with an increase of the pH which increases the
susceptibility of the mash to bacteria"
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that is something I'll definitely give a try.   The people I learned from used citric, and when I've used it it's been fantastic.  I'll read that article and give it a whirl.  Thanks.

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  • 2 weeks later...
On 7/26/2021 at 8:18 PM, LuckyGuy said:

Either offer an alternative, or don't condemn.   I've used it for 3 years with very good results.   If you have an alternative that you've used, I would gladly listen.

 

 

This forum has a wonderful search function. We've covered this topic before at length in multiple threads, my favorite is below

Albeit for rum, the chemistry still stands.

 

As for personal anecdotes, a consult of mine received a 91 and an 89 on a pear and an apple brandy, both of which we adjusted with citric. Judges notes came back calling us out for doing so. Also, Nancy Fraley trains people (specifically spirits judges) to recognize the affect of citric adjustment in grain whiskey, and your scores in pretty much all the major competitions will suffer for doing so as she has trained almost all of those judges pallettes.

 

If you don't believe me, fine, search function we've had the judges discussion before too.

 

The theory behind it is Citric acid is an organic acid, which will affect transterification of your mash because it is a carboxylic acid. Carboxylic acids and ethanol create esters through massive cascading reactions.

Mallic Phosphoric and lactic are all generally safe effective and common PH adjusters in large scale operations. Some people use sulfuric. 

[quote from linked post below]

"   On 5/25/2021 at 3:23 PM,  Foreshot said: 

 

So to explain this a little (for everyone aside from SCD) - citric acid is a carboxylic acid where sulfuric isn't. Citric acid will take part in esterification reactions, sulfuric won't. So when you added Citric acid you changed what esters were being formed. If you used sulfuric it would have enhanced what esters were previously being made. You wouldn't change the flavor as much as enhance it. The flavor might change though as the catalyst will enhance all esterification reactions, not just the "good" ones."

 

But oh wait! Lactic is an organic you say? Yes it absolutely is, but it is not citric. Citric and lactic perform in identifiable and predictable ways in esterification. Lactic has been deemed acceptable and appropriate from its tradition in bourbon and brewing in general. or, in another way, lactic will do what we want it do, citric won't (from a flavor perspective).

 

 

Edited by SlickFloss
edited for clarity on what was a quote or not
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2 hours ago, SlickFloss said:

Lactic has been deemed acceptable and appropriate from its tradition in bourbon and brewing in general. or, in another way, lactic will do what we want it do, citric won't (from a flavor perspective).

+1 on that. From my relatively limited experience it adds mouthfeel & reduces the burn of a young spirit.

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On 8/5/2021 at 3:32 PM, Foreshot said:

+1 on that. From my relatively limited experience it adds mouthfeel & reduces the burn of a young spirit.

Thanks again for that great original post, and all the other knowledge [available by forums search function, or you can look up all of Foreshots post's on his profile page] you've shared here through the years

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