Tips on getting final gravity lower for molasses rum wash?

[Doctor Dunder]

Hello! Asking for some rum wash fermentation advice! My issue is I cant seem to get my final gravity below 1.05, and I feel like I’m leaving a lot of sugar left in the wash! I’ve probably run about a dozen batches tweaking a lot of variables but always seem to end with the same FG.

Here are the specs of my wash. My recipe has been around 1 gallon of molasses, 1 gallon of dunder, 3 gallons of water, and 2 tbs of yeast.

The variables I’ve tweaked are different types of molasses (black strap and feed), different yeast types (distillers and bakers), various levels of dunder, between 0.5 gallons to 1 gallon, and have experimented with different yeast nutrients like Vitamin B or epsom salts. Fermentation times run on the longer side, around 5 to 10 days. I usually try to isolate and change one variable each batch, I've kept good notes, happy to discuss specifics. My original gravity is usually around 1.07 - 1.08, and starting PH is usually around 4.5-5.0. Fermentation temps have been warm (in a garage here in Texas).

I am attempting a pure molasses/dunder wash, and trying to avoid adding any additional sugar if I can help it, as my goal is to achieve high flavor high ester rum.

No matter the variables I tweak I consistently end up with about 1.05 final gravity, usually around just 2.5-3% abv! After a dozen or so batches I think it might be a systematic issue perhaps? Any advice or direction would be greatly appreciated! Thanks!

[Bolverk]

With the quantity of dunder and molasses you're using 1.05 is probably the lowest you'll get. It's likely nonfermentables anyway.

It's not uncommon to have a starting gravity of 1.1 +/- to have enough sugar to finish out at 1.05 to make the run worthwhile in rum.

Taste the beer, if it's sweet, you're not done fermenting. If noticeably bitter, you got all the sugar fermented and it's good to run.

[Doctor Dunder]

That's at least good to hear about the final gravity around 1.05 being more normal. I wonder if I should also focus on getting the starting gravity up then. Perhaps I should increase the quantity of molasses in the wash? My original gravity is around 1.07/1.08 - would be awesome to see it in the 1.10 range. Currently only getting around a 3% abv on the wash, which is giving me very small yields when I distill.

[Twisted Brick]

From my limit reading on rum and molasses, not all molasses are the same and possess varying amounts of fermentable sugar. For example, fancy molasses can contain 65-70% sugar while blackstrap can contain less than 50%. You pretty much get what you get and noodling around with starting and finishing gravities are apparently par for the course, as you have surmised.

Differences in sugar cane and beet molasses

Rum, Molasses, Brix, Total Sugars and Potential Alcohol

[Bolverk]

That's at least good to hear about the final gravity around 1.05 being more normal. I wonder if I should also focus on getting the starting gravity up then. Perhaps I should increase the quantity of molasses in the wash? My original gravity is around 1.07/1.08 - would be awesome to see it in the 1.10 range. Currently only getting around a 3% abv on the wash, which is giving me very small yields when I distill.

Definitely normal. And yes, calulate the fermentable sugars using a calculator and just make the wash. Blackstrap is about 50% sugar and 1 gal weighs 12 lbs, so that's 6 lbs of sugar.

I'd use the sugar wash calculator on the SD site
https://calc.stilldragon.org/ and add the quality of water needed to hit my desired SG. Keeping in mind you'll already have a 1.05 you only want to have sugar wash potential of 1.05 so you stay at or under 1.1.... That's about 5.5 gals for a 7.5% abv potential.

I routinely started with an SG of 1.1 and ended around 1.045-1.05 with no problems with plain ole baker's yeast.

I will say there is something unique about these high gravity ferments... I wasn't able to quantity it, but the rum is better in my opinion.

[higgins]

I've only made 3 rums, so take this with a grain of salt. My highest FG has been 1.015. I keep them about 90-95F during fermentation, and oxygenate really well before pitching. Fermentation takes a week or less to achieve the stated FG.

Batch 1:
1 gal Golden Barrel Blackstrap (11.5 lb)
11.5 lbs demerara sugar
9.5 gal water
2 tbsp yeast nutrient
4 tbsp DADY yeast
OG 1.081
FG 1.005
10.4% ABV

Batch 2:
5 gallons GB Blackstrap
1 gal dunder (1.030)
20 gal water
2 tsp gypsum
2 tbsp yeast nutrient
4 tbsp DADY yeast
OG 1.082
FG 1.015
8.95% ABV

Batch 3:
2 gal Evolved Habitats deer molasses (23 lb)
20 lbs panela sugar
1 gal dunder (1.028)
20 gal water
1/4 cup bakers yeast boiled for nutrient
1 tbsp yeast nutrient
2 oz shell grit hung in fermenter
1/4 c bakers yeast
1.074 OG
1.014 FG
7.9% ABV

My next one will be 5 gal of the EH molasses.

[shadylane]

That's at least good to hear about the final gravity around 1.05 being more normal. I wonder if I should also focus on getting the starting gravity up then. Perhaps I should increase the quantity of molasses in the wash? My original gravity is around 1.07/1.08 - would be awesome to see it in the 1.10 range. Currently only getting around a 3% abv on the wash, which is giving me very small yields when I distill.

More molasses to raise the OG
Less dunder to lower the FG
Fermenter temp control.

[subbrew]

I don't see anything about oxygen in this thread. To get good yeast growth they need oxygen. I use an aquarium air pump and a stone for at least 45 minutes in a 36 gal wash. And if I remember I give it a second shot 8 hrs or after pitching if my starting gravity is over 1.070.

[Yummyrum]

Have a look at Saltbush bills All molasses topic
viewtopic.php?p=7530801#p7530801

The mixing and Oxygenation of the wash can be a tricky thing to do but Saltbush does it quite simply using a pressure washer . It mixes , oxygenates and adds water all at the same time .
At first I thought it silly ,but it works well .

Also , that topic is full of useful info about all molasses washes . Its also full of folk saying exactly same as you , IE , wondering why they end up with a high FG .

Now Salty and I were both playing around with this on our own . When he started this topic , I was amazed that we had both came to almost the same proportions of Molasses , Dunder and water .

Think about the dunder . Each time you add it , you are adding unfermentable stuff to the next wash . After stripping , you have lost at least a quarter of the liquid , so the dunder is even thicker .
Remember that the molasses that you add to each batch contains 50% unfermentable “stuff” . At the end of fermentation it is still there . (Unlike a pure sugar wash where everything is converted to alcohol .)

So after stripping you now have a pot of dunder that still contains the same amount of unfermentable “stuff” but is actually “thicker” now because you you have stripped off 1/4 of the volume .

Now you add this to the next wash and you are adding more unfermentable sauce yo the next batch of molasses, of which only half will ferment .

Each time you add Dunder , you are making the wash thicker and thicker .

The trick is to add no more than 10% of your wash volume as Dunder .

I would strongly recommend you follow Saltbushs method and amounts .
Yes, the starting gravity will be roughly 1.120 - 1.140 as Bolverk said .

The end gravity will be somewhere between 0.060- 0.070

[Beerswimmer]

Maybe toss a handfull of seashells in your fermenter? The cause of 99% of my stalled washes in the past were due to low PH.

[Saltbush Bill]

Maybe toss a handfull of seashells in your fermenter?

As long as you don't use to much backset, shells and PH adjustment are not needed in a molasses wash.
The percentage recommended by Yummy is spot on.

[Yummyrum]

Maybe toss a handfull of seashells in your fermenter? The cause of 99% of my stalled washes in the past were due to low PH.

Thats pretty well right for sugar washes Beerswimmer, or even Rum washes with only a smidgeon of Molasses , but all molasses washes are quite special in that they seem to self buffer . IE , there is so much dissolved ions in there from the Molasses processing that the small amount of acid produces during fermentation has no effect .


Copied from pg 17 in Salt’s All molasses Rum topic

Another 180litres finished . Finish Gravity 1.060

pH 5.4 …… thats right …. no shells … no pH futzing required

IMG_0335.jpeg (11.21 KiB) Viewed 3379 times

IMG_0336.jpeg (19.3 KiB) Viewed 3379 times

Edit: That weird looking scum thing next to the pH meter is some reflection . The surface was actually dark brown all over .

[shadylane]

Throw in a good handful of Lowans or other Bakers Yeast.

[NZChris]

Research how much fermentable sugar to expect in your molasses.

Decide on your desired ABV for your wash.

Use a calculator to work what you have to do to get that ABV using that molasses.

The result will seldom be what you calculated, so use the results from the first ferment to calculate what you have to change for the next ferment.

I usually start a series of rum ferments with a single strip of wash to provide the dunder for the next, larger, ferment and to give me the information I need about the molasses that I need for planning what I have to do for the next generations of ferments.

If I had a supplier who reliably provided me with a consistent quality of molasses, I would have much more rum aging in my shed than I do now.

[kennstminet]

The end gravity will be somewhere between 0.060- 0.070

This looks like a typo. Did I miss something?

[Yummyrum]

The end gravity will be somewhere between 0.060- 0.070

This looks like a typo. Did I miss something?

Doh , correct kennstminet

1.060- 1.070

[Doctor Dunder]

Thanks for all the responses - super helpful. I think the culprit as some of y'all pointed out was with the molasses. The blackstrap I was using I believe had some sort of preservatives in it (sulfates perhaps?) It was killing the yeast off. A good warning because nothing on the label said anything about preservatives - it just said "all natural" but not sure if that was true.

I ran an identical batch (keeping all nutrients, yeast, ratios, etc the same) but used baking grade molasses instead of the blackstrap I was using, and it was down from 1.10 to 1.04. My blackstrap went from 1.09 to 1.07. Huge difference! Looks like I'll be using baking grade molasses (taste better also).

[Bolverk]

Baker's grade also has more sugar so it will ferment a little lower. Baker's or fancy molasses is about 65-75% sugar where blackstrap is about 50%. I've also seen some lower grade feed molasses that's 37%.

I've had good luck with the golden barrel brand blackstrap, but yes, it will leave you with about .045 gravity points that won't ferment out.

[JustinNZ]

Keep your eye out for a different or recommended blackstrap though, cos it does make a tasty rum and is worth experimenting with. I did a fair bit of searching to find my regular molasses. We’ve been going steady for a while now.

[Saltbush Bill]

I don't think you will find many of the worlds better rums made using fancy grades of molasses.The exception would be a few of the modern trendy craft distillery's.
As far as I am aware most of the the bigger commercial distilleries use blackstrap/ the sort that is fed to horses and cows here in Australia , trucked in straight from the mill......or the distillery is built right next to the mill for convenience.
IMO Rum started of as a way to get rid of a by product from the sugar industry that few others wanted in the quantities available.
I guess I'm lucky to life in sugar cane country, no shortage of the stuff here.

[Doctor Dunder]

Any recommendation on what brand of blackstrap or molasses in general y'all are using? It can be a bit difficult to shop for it sometimes! I'm using Golden Barrel Bakers grade.

[Bolverk]

I buy the golden barrel blackstrap here

https://www.webstaurantstore.com/golden ... KSTPP.html

[Yummyrum]

I buy the golden barrel blackstrap here

https://www.webstaurantstore.com/golden ... KSTPP.html

LOL , the spec sheets not giving much away
Hmmm so how much sugar is in it exactly

Chemical Properties
pH 5.0 - 6.5
Brix, % 79.0 – 80.0
Ash, % 10.0 - 15.0
Invert Sugars, % 6.0 - 22.0
Total Sugars, % 45.0 - 60.0
Sucrose, % 30.0 - 46.0

[Bolverk]

LOL , the spec sheets not giving much away
Hmmm so how much sugar is in it exactly

Chemical Properties
pH 5.0 - 6.5
Brix, % 79.0 – 80.0
Ash, % 10.0 - 15.0
Invert Sugars, % 6.0 - 22.0
Total Sugars, % 45.0 - 60.0
Sucrose, % 30.0 - 46.0

Right, not exactly precise are they.

From my experience it's been about 50-52% sugar in the 5 buckets I've purchased from them.

[Stags]

@OP I don’t have much experience with all molasses washes but I do quite enjoy my panela ferments

One thing I would definitely recommend is inverting the sugar. And by that I mean heating it in a large pot until it hits a low simmer and adding 2 tbsp citric acid. I don’t use gravity so can’t quantitatively state outcomes are better but my yield seems to go up. Food for thought.