Stuck ferment for barley wort

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Gilnockie
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Stuck ferment for barley wort

Post by Gilnockie »

Hi Distillers

Hoping someone can help me but I might already know the answer, I have been having this issue with some four grain bourbons as well

I have a single malt barley wash that had a starting SG of 1.054 extracted from the mash and I am adding glucoamylase and some yeast nutrient at pitching temp but the best I can get of it is down to about 1.021 SG so have a lot fo unconverted sugars. The ferment lasts about two days and is pretty vigourous for that time but after that complete stops but the only thing I am not controlling is the temp of the fermenter and it can get pretty low in Auckland NZ overnight in winter so in my basement room where I have all this setup is about 10 degrees celsius or 50 fahrenheit and about 18 degrees celsius during the day

What am I doing wrong? Is it the Temp and do I need to control it at about 25-30 degrees C? Water PH in Auckland is about 7.5-7.9 so not sure if PH is the reason.

Cheers

Gus
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Re: Stuck ferment for barley wort

Post by Sporacle »

Sounds like temp, check the range from your yeast recommendation, fermentation creates heat so it may be as simple as insulting your fermentors and monitoring the temp of the mash as it ferments, add insulation or open lids as required, good luck :D
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Re: Stuck ferment for barley wort

Post by Saltbush Bill »

What yeast are you using ? Different yeasts work best at different temps, Room temp isnt a great indicator of wash temp. The yeast in washes and mashes will often generate enough heat of their own and will keep them selves warm in the first few days and often rise in temp over that time, its after that, that they often drop in temp.
Without knowing yeast type it hard for anyone to give an accurate answer.
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Re: Stuck ferment for barley wort

Post by shadylane »

Gilnockie wrote: Mon Sep 13, 2021 12:47 am

I have a single malt barley wash that had a starting SG of 1.054 extracted from the mash and I am adding glucoamylase and some yeast nutrient at pitching temp but the best I can get of it is down to about 1.021 SG so have a lot fo unconverted sugars.
Tell us more about how your mashing the malt barley.
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Re: Stuck ferment for barley wort

Post by bluefish_dist »

I found pitch ph makes a huge difference in how a wort finishes. Get that 7 ish ph down to 5.2-5.4 for pitching and see how it finishes. Also temperature can cause problems as well, but fermentation is exothermic so it shouldn’t be an issue unless it’s down in the teens (60’s).
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Re: Stuck ferment for barley wort

Post by Ben »

The starting pH is almost irrelevant to fermentation. What is the pH when you are finished sparging? There is a lot that changes during the mash, but you really want to be somewhere between 4.2 and 5.4 on mash in. If acidulated malt is available that could help, lactic, malic or phosphoric acid could also do it, lactic would be preferred, malic will turn to lactic, phosphoric will cause calcium to precipitate and can end up getting you too acidic. Both lactic and phosphoric are naturally occurring in the ferment in one form or another. You could also use backset, which is cheap and available, but you would need to invest in a pH meter so you can dial in your starting acidity.

You say the ferment is stuck, is this verified with hydrometer readings, if so what are you getting for a reading, and what is the grain bill, mash temp and mash time? An airlock is not a good indicator of fermentation behavior.

5.2 stabilizer is no where near effective enough at the recommended dosage to correct that level of pH imbalance. It has been titration tested by numerous home brewers and is largely ineffective unless you are using a lot... which is going to create a salty wash.

Get yourself some acids and salts, and download the bru'n water calculator. You will just need your water report and you can dial in.
:)
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Re: Stuck ferment for barley wort

Post by bluefish_dist »

Ben wrote: Mon Sep 13, 2021 5:56 am The starting pH is almost irrelevant to fermentation.
I found pitch ph was important on how my fermentation finished. My hypothesis was that the ph at pitch effects how the yeast propagates. Get it wrong and the yeast doesn’t propagate as well and thus won’t finish well. I never tested it, but when I started to adjust pitch ph my worts finished better, ie .01 or more lower than when I didn’t.

I suspect that some of the t&t recipes over pitch for just that reason. I did a lot bigger batches than most here, 110-300 gal at a time and I found my fermentation was more picky about being right ph, temperature, etc as the batches got bigger.
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Re: Stuck ferment for barley wort

Post by Gilnockie »

Saltbush Bill wrote: Mon Sep 13, 2021 1:51 am What yeast are you using ? Different yeasts work best at different temps, Room temp isnt a great indicator of wash temp. The yeast in washes and mashes will often generate enough heat of their own and will keep them selves warm in the first few days and often rise in temp over that time, its after that, that they often drop in temp.
Without knowing yeast type it hard for anyone to give an accurate answer.
For this I used CL23 which I have heard lets produces very low levels of fusel oils and other congener compounds during fermentation which allows the malt and peat to come through better
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Re: Stuck ferment for barley wort

Post by Gilnockie »

shadylane wrote: Mon Sep 13, 2021 2:07 am
Gilnockie wrote: Mon Sep 13, 2021 12:47 am

I have a single malt barley wash that had a starting SG of 1.054 extracted from the mash and I am adding glucoamylase and some yeast nutrient at pitching temp but the best I can get of it is down to about 1.021 SG so have a lot fo unconverted sugars.
Tell us more about how your mashing the malt barley.
Using a Mash Tun with false bottom, putting in hot water at about 71c (should have been slightly hotter) and getting mash at 67c for 1.5 hours before using counter flow chiller to put into my fermenter at about 27c
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Re: Stuck ferment for barley wort

Post by Gilnockie »

Ben wrote: Mon Sep 13, 2021 5:56 am

You say the ferment is stuck, is this verified with hydrometer readings, if so what are you getting for a reading, and what is the grain bill, mash temp and mash time? An airlock is not a good indicator of fermentation behavior.

Get yourself some acids and salts, and download the bru'n water calculator. You will just need your water report and you can dial in.
using a refractor for measuring the SG.
6.5kg of Malt Barley, mash temp 67c and 1.5 hours for mash time

Thanks, I think its time to get serious about PH
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Re: Stuck ferment for barley wort

Post by Sporacle »

By all means get serious about PH, cl32 minimum ferment temp is 14 Max is 32, I you are below 14 with your mash temp then the ferment will stall no matter what the PH is. Don't ignore the temp it may be the simplest thing to fix the issue.
Good luck
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Re: Stuck ferment for barley wort

Post by shadylane »

Gilnockie wrote: Mon Sep 13, 2021 2:29 pm
using a refractor for measuring the SG.
6.5kg of Malt Barley, mash temp 67c and 1.5 hours for mash time
A refractometer works great for the initial measurement.
But after fermentation starts the alcohol throws off the reading and makes the gravity read higher than it is.

For mashing.
I'd use a slightly lower mash temp and a more time.
That would get better conversion and a lower final gravity.
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Re: Stuck ferment for barley wort

Post by Ben »

Toss in some powdered amylase enzyme if you have it, it may restart.
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Re: Stuck ferment for barley wort

Post by Ben »

bluefish_dist wrote: Mon Sep 13, 2021 12:05 pm
Ben wrote: Mon Sep 13, 2021 5:56 am The starting pH is almost irrelevant to fermentation.
I found pitch ph was important on how my fermentation finished. My hypothesis was that the ph at pitch effects how the yeast propagates. Get it wrong and the yeast doesn’t propagate as well and thus won’t finish well. I never tested it, but when I started to adjust pitch ph my worts finished better, ie .01 or more lower than when I didn’t.

I suspect that some of the t&t recipes over pitch for just that reason. I did a lot bigger batches than most here, 110-300 gal at a time and I found my fermentation was more picky about being right ph, temperature, etc as the batches got bigger.
I meant pH almost irrelevant at the time of mash in. That was poor writing on my part. The PH will change significantly depending on the grist and how long you run off. It definitely matters for ferment, yeast appreciate the acidic environment. So does enzymatic reaction. You need to know/predict what your pH is during the mash and at mash out.
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Re: Stuck ferment for barley wort

Post by MihiT »

If you're using Auckland tap water it's full of flourine and chlorine which won't help yeast at all.
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Re: Stuck ferment for barley wort

Post by Ben »

Perhaps you would be better to run your brew water through the still and start the mineralogy from scratch?
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Re: Stuck ferment for barley wort

Post by Gilnockie »

MihiT wrote: Mon Sep 13, 2021 4:38 pm If you're using Auckland tap water it's full of flourine and chlorine which won't help yeast at all.
I agree so I invested in a water filter, hopefully its getting most of that out of the mix but I am sure there is still trace amounts
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Re: Stuck ferment for barley wort

Post by Ben »

You can just pull your brew water into your hlt the night before to take care of the chlorine.
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Re: Stuck ferment for barley wort

Post by MihiT »

Gilnockie wrote: Mon Sep 13, 2021 6:25 pm
MihiT wrote: Mon Sep 13, 2021 4:38 pm If you're using Auckland tap water it's full of flourine and chlorine which won't help yeast at all.
I agree so I invested in a water filter, hopefully its getting most of that out of the mix but I am sure there is still trace amounts
That would depend heavily on the filter. I'd want 3-stage, UV, ceramic, and carbon.
Actually I just wouldn't go near town water for anything other than washing my socks or hosing off the truck.

Any chance you can get a first-flush diverter system and collect rain water?

Or go and buy (yuck) "spring" water in a plastic (yuck) bottle to try a ferment and see if it comes right. Would at least answer the question or eliminate it as a possibility.

Distilling water will take all the minerals out of it, so the water will be "hungry" and take them from wherever it can get. This is why it's not good to drink only distilled water - It'll absorb them out of you!
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Re: Stuck ferment for barley wort

Post by MihiT »

Ben wrote: Mon Sep 13, 2021 7:22 pm You can just pull your brew water into your hlt the night before to take care of the chlorine.
Very good low-input method, but I'm not sure overnight will do it. Probably depend on volume. And there's still all the other muck they pump into it, and whatever it picks up on the way to your place.
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Re: Stuck ferment for barley wort

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Just my final question and it may have been answered already, what was the temp of the mash when the fermentation stopped?
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Re: Stuck ferment for barley wort

Post by shadylane »

Gilnockie wrote: Mon Sep 13, 2021 12:47 am

I have a single malt barley wash that had a starting SG of 1.054 extracted from the mash and I am adding glucoamylase
but the best I can get of it is down to about 1.021 SG so have a lot of unconverted sugars


Sounds like the problem is due to not converting starches in to dextrins.
The malt may be low on enzymes
Or the mash temp maybe too high and the alpha enzymes in the malt is getting denatured before it can finish it's job.
Another possibility is the water makeup. Enzymes don't like it if your water has too much iron.
Take the top off your toilets water tank and see if there's rust buildup on the porcelain.

First thing I'd check is the accuracy of the thermometer and pH meter.
Next thing I'd do, is buy some store bought Alpha enzymes to go with the Gluco.
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Re: Stuck ferment for barley wort

Post by higgins »

If you used a refractometer to measure your FG (final gravity) of 1.021 with an OG (original gravity) of 1.054 then the actual final specific gravity is right at 1.0 according to 3 different calculators I have used.

Google 'refractometer correction during fermentation' and you'll find several.
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Re: Stuck ferment for barley wort

Post by Ben »

A little more info on pH:
I decided I would take the time to make measurements on my next wash. I cooked up a 75% corn mash yesterday, my base water pH is at 7.1. By the time the corn had cooled to mash temp, the rye and barley were added and temp stabilized my pH was at 4.8. So again, the pH really depends on what you are doing and how you are doing it. When my run off was complete I was at 5.2. Unless you are checking pH at mash in, and mash out or have some good math and chem skills the starting pH is not really that useful.

4.8 is possibly a little low, but my extraction on feed corn was 90% (I would actually prefer 88%, I need to do some tuning), so I think it was fine. You don't have to hit the "magic" 5.4 to have a successful mash. Play with your chemistry and see how you like the flavors, the taste is what is most important. Different levels of acidity are going to bring out different flavors. In my case I will add a teaspoon of gypsum next time after mash in and see how I like the flavor profile, side by side in the white.
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Re: Stuck ferment for barley wort

Post by Gilnockie »

higgins wrote: Tue Sep 14, 2021 4:33 am If you used a refractometer to measure your FG (final gravity) of 1.021 with an OG (original gravity) of 1.054 then the actual final specific gravity is right at 1.0 according to 3 different calculators I have used.

Google 'refractometer correction during fermentation' and you'll find several.
Thanks for the advice it was not something I was fully aware of
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Re: Stuck ferment for barley wort

Post by Gilnockie »

Sporacle wrote: Tue Sep 14, 2021 12:21 am Just my final question and it may have been answered already, what was the temp of the mash when the fermentation stopped?
It was at 17c
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Gilnockie
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Re: Stuck ferment for barley wort

Post by Gilnockie »

shadylane wrote: Tue Sep 14, 2021 12:47 am
Gilnockie wrote: Mon Sep 13, 2021 12:47 am

I have a single malt barley wash that had a starting SG of 1.054 extracted from the mash and I am adding glucoamylase
but the best I can get of it is down to about 1.021 SG so have a lot of unconverted sugars


Sounds like the problem is due to not converting starches in to dextrins.
The malt may be low on enzymes
Or the mash temp maybe too high and the alpha enzymes in the malt is getting denatured before it can finish it's job.
Another possibility is the water makeup. Enzymes don't like it if your water has too much iron.
Take the top off your toilets water tank and see if there's rust buildup on the porcelain.

First thing I'd check is the accuracy of the thermometer and pH meter.
Next thing I'd do, is buy some store bought Alpha enzymes to go with the Gluco.
Thanks good advice
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Gilnockie
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Re: Stuck ferment for barley wort

Post by Gilnockie »

Thanks All, I have a good advice to take note of and work on my next batch appreciate your input
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