stuck ferment with Dunder

[iwine]

This is the second time that I use Dunder.I had no luck on the first one either. it was a low-yield of alcohol.I had tried eggshells with no success. And a big ass omelet for supper. but I didn't have a pH meter at the time and I couldn't get a proper reading off of pH paper so I bought myself a pH meter.
I'm either having issues with stuck ferment or I'm suffering from lack of knowledge and I think it's the latter.
I have used the hook rum recipe many times without DunderI have fermented them anywhere from 10% to 14% and had them finish as fast as 30 hours to 48 hours.Normally the hook rum will finish dry at 1.015 or slightly higher depending on how much molasses I have in there.
I think My issue is Controlling pH in my wash but i could be wrong on that.
My recipe as follows hook rum wash.
This is 2nd generation recipe.
5 kg blackstrap molasses
5 1/2 kg panella
1 cup Baker's yeast Starter (one cup yeast 2 liters of water pinch of Epsom salt pinch of DAP water temp 95 degrees half cup white sugar let sit for about 20 minutes to make sure yeast Active)all good
1 teaspoon Epsom salt
1 teaspoon yeast nutrient
4 liters Fresh Dunder
4 liters aged Dunder
2 heaping tablespoons of calcium carbonate( precipitated chalk)
Can bucket topped up 43 l of city water
Started on lees from previous washI
didn't check specific. Gravity but from the calculators that should come out about 10 1/2 percent.
I have my ferment wrapped with a heating blanket and it's kept between 80 to 85 degrees.

day 6
When I check gravity today it was 1.040 and has been here for a couple days.it seems to have stalled. I checked my pH with a pH meter and it was sitting at 3.8 .
I added 3 heaping tablespoons of calcium carbonate and it seemed to have done nothing. then I added about half a cup and it brought it up to 4.1 then I added a total of 2 cups of calcium carbonate and I was able to get it up to 4.5. It seems to be a little excessive I think. I don't want to ruin the wash. I would like to continue with the generations but I've got to get the pH under control.

Day 8
I added 500 grams of this stuff to bring the ph up to about 4.5

green earth

Green Earth ingredients

Day 10. This morning
pH is now back down to 4.0. Sg 1.038.

for you rum Dunder guys.
question 1. how low does the SG go using Dunder are there More unfermentables to keep the SG up higher than 1.020?
question 2.How long normally does it take for a rum wash with Dunder take?
question 3. Am I not patient enough?
Question 4. is it possible to keep this recipe fermenting between pH 5 to 5.5?

What am I doing wrong? where am I missing the boat?
head scratcher

[nerdybrewer]

Well I think you're on the right track.
When I do this, using dunder and all it definitely gets lower in PH but I suspend some oyster shells.
They always come out lighter / thinner then they went in.
One problem is that whatever you put in there (shells) will become covered with goo pretty quickly.
Suspending them allows you to kind of shake off the goo.
Your numbers look pretty good, I've had several that just would not go below 1.030 and then checked and found no more fermentable sugar.
Does it taste sour, or sweet.
If it's sweet you have more time to go.

[NZChris]

Always record the Original Gravity because it is the drop in SG that tells you how well the ferment is going and how much of your calculated fermentable sugars are left. I'd guess yours is ready to run, but without knowing the OG, that is just a guess.

If my SG doesn't drop for 24hrs, I consider it done and either run it, or start the count to a chosen number of days for flavor development.

[iwine]

my wines I take SG readings religiously. with rum washes or birdwatchers recipes they work like clockwork so I only took SG readings when I first started learning and I haven't taken SG reading for over 2 years. I know I was kicking myself for not taking an initial SG reading . I'm very aware that with that reading it would have told me a lot of what was going on. My bad.
I deserve getting flamed for not taking the initial readings

I came across this thread this morning Suspending shells in the dunder washes from what I understand by putting the shells in early it stops the hard crashes and the shells help control the pH a lot better. If there are still issues I could always add calcium carbonate or something else to bring it up to desired levels.
Well tomorrow I'm off to the store to pick up some crushed oyster shells and I'll suspend them in the next wash.
I decided I'm going to run this wash on Wednesday today today the sg dropped to 1.037.
I guess maybe I was spoiled with 30 hour ferments that almost exploded and having to mop up the floor. Lol I now have a catch tray underneath my fermentation buckets.
I guess that's what these forms are for I just needed a little reassurance that what I was doing was not too far off. Just need to tweak a little.
thank you so much guys nerdybrewer and NZChris

viewtopic.php?f=3&t=69858&p=7513861&hil ... t#p7513861

[ShineonCrazyDiamond]

If it is a ph issue, and not a temp issue, you can still recover with pickling lime, (milk of lime). Shells are preventive, lime recovery.

What's the temp your running?

[nerdybrewer]

If it is a ph issue, and not a temp issue, you can still recover with pickling lime, (milk of lime). Shells are preventive, lime recovery.

What's the temp your running?

He said it was 80-85F which is the sweet spot for this rum.
You are right about shells, I put them in at the start and don't worry about ph
Recovery is a whole other animal, but the drop in SG is encouraging.

[iwine]

What's the temp your running?

fermenters wrapped in a blanket with a heating pad underneath. temperature is about 80 to 85 degrees

posted the same time as nerdy Brewer

[OtisT]

Another must for complete fermentation is proper aeriation. Just before pitching yeast, aeriated the hell out of the ferment. I use a cheep ass aquarium pump W/air stone for at least an hour or more as the ferment is cooling down to pitching temp. Once you pitch, don’t mess with the ferment to prevent any more O from getting to your ferment.

Also consider a bit less dunder. 20% may be a bit high if you are not experienced with this type of ferment. Maybe 10% to start.

Otis

[Saltbush Bill]

Also consider a bit less dunder. 20% may be a bit high if you are not experienced with this type of ferment. Maybe 10% to start.

Excellent advice Otis.
From my own experience making Rum I know that if I use no more than 4-L of dunder in a 28-30L ferment I never have to worry about PH or adding things to adjust PH. Staying at that ratio regardless of ferment size works fine.

[iwine]

Oops dah I guess I forgot to mention in my initial recipe. I do use a fish pump and aeration Stone in all my washes. I run them from anywhere from 1 to 2 hours after I pitch the yeast.
I will be starting 3rd generation of this recipe by the Weekend. I'll cut back the dunder to 10% Of the wash.
Thanks Otis and Saltbush

[nerdybrewer]

Oops dah I guess I forgot to mention in my initial recipe. I do use a fish pump and aeration Stone in all my washes. I run them from anywhere from 1 to 2 hours after I pitch the yeast.
I will be starting 3rd generation of this recipe by the Weekend. I'll cut back the dunder to 10% Of the wash.
Thanks Otis and Saltbush

Good kick to the memory here!
The times I have had the most trouble were the times I used the most dunder.
Once I used about 1/3 dunder, that one was a bear and took over a month and I never was really sure it was finished but then when I ran it the quantity of output fit the math.
Good catch guys!

[Yummyrum]

5 kg blackstrap molasses
5 1/2 kg panella
1 cup Baker's yeast Starter (one cup yeast 2 liters of water pinch of Epsom salt pinch of DAP water temp 95 degrees half cup white sugar let sit for about 20 minutes to make sure yeast Active)all good
1 teaspoon Epsom salt
1 teaspoon yeast nutrient
4 liters Fresh Dunder
4 liters aged Dunder
2 heaping tablespoons of calcium carbonate( precipitated chalk)
Can bucket topped up 43 l of city water
:

iwine
You are Fermenting at a nice temp range , that's important. Keep it high and fast .
If I read your recipe correct , you are already less than 10% Dunder . ......that's perfectly fine

Now remember that Dunder is a concentrated ( boiled down ...the alcohol and a fair bit of water have gone ) version of your last wash so it will have a high Specific Gravity ....it contains all the salts and minerals from the last wash and the wash before that and so on . Add this to your next wash and you raise the starting gravity already by an amount that can't be fermented .

Last time I tested my Dunder it had a gravity of around 1.060 combine that with molasses which also contains a lot of unfermentable stuff and you always end up with a high finish Gravity .( so what you ended up with is pretty on par for a sugar /molasses wash only a few gens in )
Back when I last checked my Dunder , my wash was finishing around 1.055 . Nowadays ( read 3-4 years later ) my wash is finishing closer to 1.065- 1.070 so my Dunder must be getting real high in Gravity now ( must re-check it for curiosity's sake ) .

The thing is that in all the time , my wash always finishes in a couple of days . I don't worry about pH . In fact the more washes I make , the more stable it seems to becomes .All the concentrated material in my Dunder seems to Buffer or Clamp the wash pH , that and the molasses . Did you know that when they refine sugar they add heaps of Calcium Hydroxide during the clarifying stages that remains in the Molasses , they then add quite strong acid to balance out the Calcium Hydroxide so all these salts are " Clamping " the pH way more than a few shells and stuff we might like to kid ourselves are going to make a difference to a Rum fermentation .( sure it works on a sugar wash which contains hardly any Salts ...but this isn't a Sugar wash )

So bottom line , taste it , if its bitter its done ....don't get too hung up on finish Gravity or pH . Good to keep an eye on them but that's about it .

[iwine]

I'm still kicking myself for not taking an SG reading at the beginning of this recipe.

day 14
my ferment is still moving along slowly. Sg reading is 1.034 pH is 4.0.
I gave up on trying to control the pH on this ferment. I guess I'll have to be a little more patient. As long as it's moving forward I'm golden.
my next ferment I do want to control the pH between 5 and 5.5. I will be suspending oyster shells in my next ferment as a buffer. I will also reduce the dunder down to 10% instead of 20 percent

You are Fermenting at a nice temp range , that's important. Keep it high and fast .
If I read your recipe correct , you are already less than 10% Dunder . ......that's perfectly fine :

I have 8L of Dunder in a 43 l wash is actually 18.6% Dunder

[iwine]

This afternoon I decided to check the gravity and pH of my fresh and aged Dunder.
I was a bit surprised at the results

fresh Dunder

sg fresh dunder40

ph fresh dunder

my four-year-old dunder bucket

sg aged dunder

ph aged dunder

I was expecting my age Dunder bucket to be a lot more acidic and I was also expecting the SG to be higher. with both of the SG being at 1.010 there isn't that many unfermentables in there
I was also expecting the pH’s to be closer to 4 and the Aged Dunder bucket to be below 4.Instead they were mid-to-upper 4’s for pH Head scratch,
you learn something everyday

[iwine]

So if I've done my math correctly and working backwards my starting gravity should have been about 1.080 give or take a couple hundreds of points. including the unfermentable. I was thinking that possibly the fresh molasses would have added another 10 points so it could have been as high as 1.090.
So theoretically for my wash to be finished my reading should be as low as 1.020 to a high of
1.030. I'm just thinking out loud. I could be totally out to lunch on this

[iwine]

Okay yes I was a little slow Distilling this wash. I just Distilled it three days ago the final SG was 1.031 and It. sat at that SG for 5 days so I figured it was done and let it air out for 3 days and then did the cuts last night.

I got 23 jars at roughly 250 ml per jar I distill down to about 20% . after taking a hundred mL of 4 Shots the heads jars were sharper the normal they were very hot to The Taste .
And now for the tail cut something that surprised me what is there was no discernible wet cardboard taste except very slight in jar 13 jar 12 was kind of weird to me, it had kind of a peppermint taste to it so I got my wife involved to taste the jar and I did not tell her what I thought. so she tasted it and said the exact same thing it tasted like peppermint or minty.

Now for the hearts I had a heck of a Time trying to figure out what to keep. there is little to no molasses flavor at all, I have had neutrals with more flavor. throughout all the jars there was a very very salty taste and a slight chemical flavor Throughout all of the jars. I was very disappointed in the outcome I only kept About 1 ½ liters. and with this I'm not even sure what I'm going to do with it it's undrinkable. Maybe I'll throw some chard oak on it and let it sit for a year and see what happens . the heads and the Tails were so bad I didn't want them in my faints jar I threw them out.

My conclusion is the wash ended up too acidic and with the amount of Base that I was trying to control it with gave it the salty taste and off flavors. basically when you mix acid and base you got salt water.
What surprises me the most is there is been hundreds of generational washes made using dunder and nobody seems to had issues this bad. I'm very confused



Your thoughts and comments would be greatly appreciated

[iwine]

PS
I just did the exact same wash accept without dunder and went with 10 kg of blackstrap molasses It finished in 40 hours at a 10% wash.I'm going to run it tomorrow

[ShineonCrazyDiamond]

I gave up on dunder in the ferment. I mix the dunder in the low wines over night before distilling now. Simple fix.

[frunobulax]

A couple things , - NO sugar when your re hydrating yeast, the object is to hydrate the cells, not jump start them, especially with a different sugar then your gonna ferment with.
I'm not a dunder guy either, I think there is plenty of flavor in an all molasses wash and ya won't have to worry about ph crashes. A ph of 3 is around is where I found to be the stalling point to be, but I think
your problem was over thinking your starter, sugar, Epsom salt and DAP.
About no flavor, sometimes you'll be surprised that it comes out later while oaking.

[OtisT]

What surprises me the most is there is been hundreds of generational washes made using dunder and nobody seems to had issues this bad. I'm very confused

I guess I am nobody then. I had an epic fail very similar to your experience. One particular batch of molasses rum w/ dunder was a bust after I put every high ester trick into it. Turned out to smell/taste chemically like a bandaid. Had a similar off note from heads to tails. I’ve not given up though. 8 months and counting in the barrel and it still has that smell. Otis

[SaltyStaves]

Sounds like too much lime. You can't trust a pH meter will lime additions in molasses washes.

[Saltbush Bill]

One particular batch of molasses rum w/ dunder was a bust after I put every high ester trick into it. Turned out to smell/taste chemically like a bandaid. Had a similar off note from heads to tails.

You dont need to go to extremes to make good Rum, Im sure half of these PH and other problems come from people over thinking things and adding assorts of stuff to washes.
Plenty of mollases, little sugar if any and not to much dunder works for me every time and gives a good flavourful Rum. Never had a failed wash yet in 7-8 years and hundreds of washes..or any complaints about my rum.

[SaltyStaves]

You dont need to go to extremes to make good Rum....

Its not possible to make anything resembling a tropical Caribbean high ester rum with just molasses, water and baker's yeast.
Some of us are trying to make rum emulating that style. Its not to say the rum you make and like isn't good. Just different.