Rum, Molasses, Brix, Total Sugars and Potential Alcohol

[gundog48]

I was hoping someone more familiar with rum fermentation could pitch in here.

I'm looking to create a ~10% ABV wash from blackstrap molasses. All the source material I can find recommends diluting back to roughly 18 Brix (which would be 10% potential alcohol) and fermenting. But my molasses is only about 56% total sugars, which would effectively mean an actual sugar concentration of 6 Brix and a roughly 6.5% potential ABV.

In these scenarios, do I ignore the apparant gravity and simply focus on the actual sugar concentration, or would bringing that up to an apparant 26.8 Brix put too much stress on the yeast, despite not actually being sugar?

In addition, has anyone had any results adding more sucrose to the fermentation to bring the fermentable sugar level up artificially? For example, in an example where we have molasses with 83% total solids and 56% fermentable sugars, adding 300g of sugar to every kilo of molasses, to effectively raise the fermentable sugars to 75% and increase yield?

Your input would be greatly appreciated!

[durty_dunderpants]

In these scenarios, do I ignore the apparant gravity and simply focus on the actual sugar concentration,

i'm also curious as to the effect of the unfermentable solids on the yeast, but can at least say anecdotally that it's not an obvious problem. you may want to aim for a little lower than 10% abv to further reduce yeast stress and associated off-flavours.

regards adding sugar to a mash/wash, recommend looking in the tried and true section and most every rum recipe on this site
buccaneer bob's even takes it a step further

[frunobulax]

I just go by the sugar content. A gallon of that molasses made up to 5 gallons of wash, should be around 7% . I you want it stronger, use a little less water, using sugar, to me, always gives booze that sugar bite.

[Yummyrum]

I make Rum out of Blackstrap Molasses that has a sugar content that is close to but under 50% . I used to concern myself with ozmotic stresses that the likes but it just doesn't seem to matter as much as you would think . I use good old Bread yeast and it quite happily devours all the sugar in the mollases . There is nothing sweet left after its done its job .
Heres a link to how I typically do it and note the Starting gravity in the 8th picture .
It would have the beer brewers in disbelief
viewtopic.php?t=16491&p=7500204#p7500204

[Shine0n]

I also have a recipe in the "sugar" section and I do use sugar or say dark brown sugar to increase my yield with no ill effects and not one soul has said it's not a fine rum.

I've done an all moll wash and had to redistill it twice to get a palatable drink, with mine ran with a thumper I can get a nice bold rum in one pass.

Each to their own I'd say but I will say that if not added to an extreme amount, sugar can help out without off flavors.

10% can be handled by many yeasts and is about what my recipe is although using a hydrometer will read high but that's very easily sorted by simple math OG-FG× 131

Will give you the potential ABV
Or dip your finger when you suspect it to be finished and it won't lie to you. lol

Good luck with your rum and I'll keep an eye out for your recipe= subscribed!

[googe]

I'd forget readings, I always have. All molasses will give you a better rum compared to molasses sugar mix. unfermentables have never been a issue for me. You get a nice big Lees bed with the crap left over, and its great for.next gens. Just work out molasses sugar concentrate to per liter to general sugar wash amounts and you can't go wrong.