Molasses fermentation yield

[jestemknajtem]

Hi, I've fermented 300l of mollases wash to ~12% abv and I only got around 25l of distillate. I am a home distiller and I am curious why i didn't get more of it. Are there any equations that would help me to know how much distillate should I get? Im a newbie to the forum.

[meerkat]

The fermentation yield depends on a host of different variables, but if you know that there was 12% ABV in the wash then the fact that you produced only 25 liters of distillate is not due to anything being wrong with the fermentation yield. 300 liters of wash at 12% ABV distilled to 94% ABV should give you around 38 liters of total distillate (i.e not just the hearts).

There are 3 areas where you should start looking for the problem. Firstly, how did you measure the 12% in the wash? This is quite a high level of alcohol for a molasses fermentation and maybe the alcohol was never there to be recovered. The second potential problem would be losses in the distillation process. If you are doing a batch distillation then the only way to lose alcohol is if uncondensed vapors are passing through the condenser. Was your condenser running cold enough? Distillation efficiency should be 98%+. Lastly you should check if any alcohol was left in the pot after distillation.

[RumBumm]

With the 12% ABV did you measure the before and after fermentation SG? when I started on this journey i would try to push a high ABV in the wash with lots of sugar. the problem happens that you are then susceptible to a PH crash which stops the fermentation process and leaves the sugar in the wash. The result is that you don't get the yield you were thinking of when you distill. check you Ph during you fermentation to prevent it from crashing.

[Dsking416]

You could also lose alcohol to heads and tails. If your fermentation tem is too low it will make lots of tails. You wouldn't bother to collect them but it is technically alcohol and all analog measurement methods account for all types of alcohol.

 

I've had many clients from the wine, beer or cider industry not understand that most of the alcohol they make comes through as tails to us. I've even seen as low as 10% yield because the "Fermentation Scientist" wouldn't let it ferment warm enough.

 

 

Also, definitely adjust the pH before and during. Minutely, but keep the yeast comfortable.

[Stonecrest Distillery]

When using Molasses, what is the best way to check and correct pH during a Rum ferment?  What is the group's preferred method?

[Bolverk]

I create a buffer when I'm making the wash and don't typically need to make pH corrections mid ferment.  I use lye to raise the pH up to 7 then sulfuric acid to drop it back down to 5.8. I've yet to have it drop below 5 when the wash is done.