DME Stuck Fermentation

[AnotherDrum]

I was trying to do a DME 'scotch' wash. OG was 1.090 and it has stalled at 1.050. Holding temp at 85, and I have used S-04, bread yeast, and whiskey yeast..Nothing is getting it down. I added yeast nutrient at the beginning, but still nothing.

Thoughts?

[shadylane]

How long has it been fermenting and what are you using to measure the SG?

[quadra]

That is way too warm for 04 and most bread yeast... do you have any way to check your Ph?

That is a very high gravity wash and your yeast are going to be stressed and produce a lot of nasties as a result. It may not seem intuitive but good spirits are easier to make and cleaner at lower gravity when your yeast are not stressed. There is a point when they have produced enough alcohol / byproducts/ Ph changes, that the wash becomes hostile to the yeast and they slow or stop before full attenuation.
What kind of DME did you use? It may be that you have maxed out your fermentables.. or that it was underpitched. I like to keep EC1118 handy for stuck fermentation, but your max potential at that SG is nearly 12% !!

[Homebrewer11777]

Are you using a refractometer to measure SG? If using a refractometer to measure SG of fermenting wort you have to account for the presence of alcohol.

[AnotherDrum]

Thank you all for your response - and couple of things.

1. I can't believe I haven't checked my pH lately. I did at start of fermentation and it was 4.6
2. Initially I pitched FermPro 917 yeast at 85 degrees, which is supposedly the sweet spot. Gravity dropped to 1.050, but nothing more in 2 weeks (3 weeks total now).
3. I use hydrometer to measure (calibrated)
4. So....yeast... (sigh). When there was a stall, I did cool it down to 69 and pitched the S-04 with no movement...after 4 days with no movement, I co-pitched bread yeast and DADY with an increase back up to 80.....no.movement...so now i have a yeast bomb too

I am going to check the pH in a sec; i very well may have stressed it all out. Crap. Going forward, what is an ideal SG to yield an excellent product? I'm liking the price point of FermPro 917.

[Homebrewer11777]

More yeast can't really hurt. Perhaps another slug of DADY at higher than normal pitching rate. Up to 4 grams per gallon. Hydrate the yeast. Gently stir the ferment when you add it.

DME should really not need any yeast nutrient. Oxygen at beginning of ferment would have been desired but probably not now.

Thinking you might try a bit of glucoamylase too. My idea is that the sugars in the DME run a range from highly fermentable to moderately fermentable to unfermentable. The profile was locked in at the factory. The yeast start eating the most fermentable simplest sugars. Then slow down a bit and chew their way through the the remaining sugars, finally giving up the ghost when they get to minimally or non fermentable sugars. Faced with high alcohol and other by products they get tired easier. These fresh yeast you add are not going to get a chance at any minimally fermentable sugars...but bit of glucoamylase could change that and give them some help.

[bilgriss]

I've never had a DME ferment just stall. S04 likes cooler temps, yes, but its advertised upper range is about 79F, so you aren't crazy out of there. It will throw some strong flavors at high temps though. Bread yeast is happy at 85.

Two other things to consider. One, DME usually is mashed higher than is optimal for a distillation ferment, but will work great if you are careful. It will NOT finish down around 1.0 though. It will have unfermentable sugars intentionally for offsetting bittering agents (hops) in beer, and you will finish somewhat higher. Two, 1.090 is pretty high gravity. It's higher than I target for a clean ferment, and yes you are likely to stress the yeast. High gravity. High Temps. High expectations.

If you are really getting a 1.050 gravity with a calibrated beer hydrometer, you still have fermentable sugar - nearly as much as a new ferment. You can try a yeast bomb. I think I would dilute the whole thing a bit, and if the pH DOES turn out to be quite low, add a buffer as well. Lots of good threads on the forum that highlight how to go about this.

My recommendation for the future would be to "Read till your eyes bleed". Follow all the links below in the required reading section. Then pick a recipe from the "Tried and True" section of the forum which has been proven to yield consistent good results. Follow it exactly. If something is amiss, lots of us on the forum will know how it should behave and have more than guesses to help you along.

[shadylane]

OG was 1.090 and it has stalled at 1.050. Holding temp at 85, and I have used S-04, bread yeast, and whiskey yeast..Nothing is getting it down.

1.090 is definitely on the high side. 1.060-1.070 would be a better starting OG.
What DME did you use? Was it a plain malt extract or one of those funky acidic ones?
The reason I ask was 4.6 sounds low, 5.2ish or a little higher is the norm.

"I can't believe I haven't checked my pH lately. I did at start of fermentation and it was 4.6"

[AnotherDrum]

I did a pH check and it was at 3.2 today i did a correction and got it back up to 4.9, but it may be too late at this point

I used briess pale dry malt extract.
.

[shadylane]

I did a pH check and it was at 3.2 today i did a correction and got it back up to 4.9, but it may be too late at this point

I used briess pale dry malt extract.
.

Damn, that's the first time I've seen a DME pH crash.
Just guessing, by the time you read this the ferment is working again after the pH adjustment.
If not maybe something more sinister is afoot.
And it's probably not nutrients or temp. DME is rich in nutrients and 85'f is in the ballpark for a mixture of S-04, bread yeast, and whiskey yeast

[quadra]

Shady, 85 is way the hell too hot for S04 or even S05, not sure what bread yeast you are thinking of?

Another drum, what are you planning to make? DME is not cheap and most beginners tend to start with simple stuff like sugar washes.

[bilgriss]

Quadra, bread yeast loves 85 degrees, or even warmer. https://www.fleischmannsyeast.com/bakin ... yeast-101/

S04 and S05 will be active at that temperature but throw flavors that might not be desirable. Just because their recommended temperature ranges for beer are lower does not mean this temperature would cause a stuck fermentation, which is the topic of the thread.

[AnotherDrum]

I was planning to make a "scotch" but I think I blew that to hell. I've been a brewer for years and have done sugar, bourbons ( all grain, though), and agave spirits, but this was the first time using DME for a wash. I didn't think that would cause any issues and thought it would be an easier batch. I typically do.check pH..not sure why that escaped me this time, but I am.still puzzled.

[Black Bull]

I I typically do.check pH..not sure why that escaped me this time, but I am.still puzzled.

Did it recover ?

[jonnys_spirit]

DME is fine for a scotch if you want to avoid mashing. There will be unfermentabes since it's designed for beer so it's not that efficient for scotch. DME / LME stripping runs will foam a lot due to the unfermentables which makes stripping much slower. Mashing grain for distilling is a little different than mashing for beer regarding temps and required sanitation - I'd suggest that mashing for distilling is easier and less fiddly. DME/LME may be pre-hopped which is probably not ideal unless you are looking for a concentrated hops flavor in your spirit. Consider un-hopped DME/LME if that's a concern.

I would think that it should ferment easily though just like it would for a beer ferment - the DME doesn't know what you're going to do with it

Hope it restarts after boosting the ph a bit.

A pocket full of oyster shells in a "dirty old sock" thrown into or suspended in the ferment help to buffer as pH drops and prevent a crash. Good insurance.

Cheers!
-j

[AnotherDrum]

Thank you so much!!

[quadra]

Quadra, bread yeast loves 85 degrees, or even warmer. https://www.fleischmannsyeast.com/bakin ... yeast-101/

S04 and S05 will be active at that temperature but throw flavors that might not be desirable. Just because their recommended temperature ranges for beer are lower does not mean this temperature would cause a stuck fermentation, which is the topic of the thread.

What are you talking about? Do you make bread starters.... or ferment spirits? That link is for rehydrating yeast to make bread.. not to ferment a wash for distilling. A hot fermentation is the fastest way to throw your Ph into prison hooch territory... and there might be a reason brewers throughout history strive for cool fermentations. I could culture something off grocery store grapes or my gym socks that would be " active " ..

To put it another way, there is a direct relationship between temperature and Ph... yeast is Ph. sensitive.... highly stressed yeast in a hot fermentation develop overwhelming amounts f fermentation byproucts... unless you sell turbo yeast for a living explained how this is good for yeast metabolism and decomposition ??
I would also like to see any yeast guidelines that recommend either 04 or 05 in that range...


Anther drum;
That DME is an excellent product but you need to remember it is only about 75% fermentable, and the wash you want to distill should be as clean and low stressed as possible to get the cleanest spirit.... that will never happen at that gravity. High gravity brewing is by its nature less effective at converting fermentables and the high alcohol levels actually become toxic to the yeast. A fermentation at .45 or .55 would have given you a less stressed product with lower congeners to deal with because your yeast would have been in a happier place. How big is this batch?
Running this through a calculator with your starting gravity, S-04 yeast, and EC-1118 ( my go to for finishing slow fermentations ) gives a final gravity of 1.022 in ideal conditions with a target ABV of 8.78%. S04 has a tolerance of 9.75% at its maximum recommended temp of 77 degrees .
At this point you could mess around with Ph and throw yeasts at it for a possible extra 2 or 2.5 % ABV the 20 points of SG represents and risk the possibility of infection and off flavours developing.... I would probably chalk it up to experience and fire up the boiler myself. I have had my fair share of high gravity beers that never hit target, sometimes mucking about with them for the last few theoretical points just made things worse with off flavours from yeast and risk of infection... I wish I had owned a still back then

[shadylane]

.... I would probably chalk it up to experience and fire up the boiler myself. I have had my fair share of high gravity beers that never hit target, sometimes mucking about with them for the last few theoretical points just made things worse with off flavours from yeast and risk of infection...