AirStill Rum

[RoboStill]

Started another batch fermenting last night.

Slightly modified the recipe, mostly based on what I had in the cupboard. I opted not to include any blackstrap, and more brown-sugar than fancy molasses, aiming for a slightly "lighter" tasting spirit. Also going to be more vigilant with my spirit cuts, see how much flavor survives in the hearts. I think this whole batch will go on oak and into the basement, out of sight out of mind, so I can age it for at least a few months.

Sugars:
2 x 1.350 kg Fancy
2 x 2 kg yellow sugar (light brown sugar)
2 tsp yeast nutrient (edit: this was teaspoons, not tablespoons!)
Boiled in 15L water, added to 5 gallon carboy
Water added to 22L mark, cooled down to ~35 deg C

Yeast Starter:
1L of water
1 cup of brown sugar
1 tsp of yeast nutrient
Boiled, cooled to ~30 deg C, and aerated in the jar for 5 min
2x EC-1118 (5g packets)
Left for ~2 hrs, plenty of life


Threw the brewbelt and a towel on it this morning, figure it should be fermented out in a week or so. Should be good timing, as I'm about halfway through stripping a batch of neutral.

[chill]

That seems like a lot of nutrient and sugar in your starter.

Looks like a good recipe, I think you will be happy. The yeast may like a snack of some epsom salts, 1/4 - 1 tsp is what I usually see recommended, but I have seen more suggested.

If you have it available, cherry and maple might be interesting alternative to oak.

Chuck

[Uber]

Really looking forward to hearing how your latest batch turns out RoboStill.

I'm keen to start my first Rum wash and am studying many different recipes...

[RoboStill]

Chuck: is that too much? It was eyeballed from the bag (sugar) and the vial (nutrient) for the starter. For my beers and wines, I'm much more precise, as I don't want to add extra sugar to my wort or must. For this kind of wash (rum / vodka), or when I do mead, I tend to use a fair bit of nutrient to really kickstart the yeast, and I've had good results to date.

I did notice an error in my recipe; edited the post, it should have read 2 TSP of nutrient, not TBSP. Two tablespoons would be a *lot*.

The LHBS only carries oak, but I'd definitely be interested in toasted maple, I'll have a look around...

[chill]

The 1 tsp of yeast nutrient and 1 cup of sugar in a 1L starter seems a lot to me. I'd use a couple tsp of brown sugar and leave it at that. The molasses on the sugar should be enough nutrient to get it started. Maybe add a small pinch if you want.

Chuck

[RoboStill]

Thanks, I'll give that a go on my next run. Or I may just do a test batch with some EC-1118 in a jar. It's cheap at the LHBS (cheaper than beer yeasts), so maybe worth the experiment.

I've been reading a few rum posts mentioning saving the dunder for recycling. I didn't give it a second thought with my first batch, as I didn't know if I wanted to make any more rum, so it all went down the drain (sad now!) but I think I'll give it a go with this batch. The question is, how to account for the sugars and unfermentables in the dunder when adjusting the ferment recipe? Or does it really matter? I'm not overly concerned with efficiency, as I'm already making more rum than I could possibly drink myself.

[chill]

There should not be any (fermentable) sugars in the dunder. And unfermentables will remain... unfermentable. The main reason for using dunder is that it is acidic and will help get the ph lower and it adds more complexity to the flavour. Try rotting some in a covered container outside for from REAL complexity! Not saying that you will necessarily like it... Or even have the stomach to try it.

I have used 2L of dunder in a 23L wash.

Chuck

[RoboStill]

I've read a lot of different stories about leaving it outside to "rot". Sounds really interesting. Also, that the high acidity causes more esters to form during the stripping run boil (due to the heat)?

I'm surprised only 2L of dunder into a 5 gal batch. Based on the yield from my last batch, I will end up with plenty of dunder. Why such a small amount? Based on flavor and experience? Is that 2L "sour" as you describe?

[chill]

Yes, it is sour. If you add too much, the ph is to low for the yeast. I don't know if rotted dunder is sour, no way that is going in my mouth raw!

I have no idea on whether the acidity causes more ester formation or not.

Chuck

[KerryW]

I am making Robostill's rum this weekend,, Wish me luck,, and CHEERS
I will let you know how it is an a few weeks

[KerryW]

RoboStill's rum aka Roborum is frementing with a starting SG was 1.114 is this too high, but based on the it seems ok how was yours Robo?

secondly, the temp in the house is still cool at about 19-22 (winter here and heating oil is too dammed expensive) so should i use a brew belt of aquarium heater?

[chill]

I have found the brew belts to be not effective. Maybe they do better on glass than plastic. A 50W aquarium heater produced much better results for me. Just be careful to not cook your yeast. They like warm but not hot.

Chuck

[KerryW]

I bought a 100 watt heater, good for 2-15 gallon tanks, works to 25C
at 1/3 the price of the brew belt it looks like a good buy.
The RoboRum is bubbling good now,, Without the aquarium heater, so far maybe the change in location worked,,,

[RoboStill]

My first batch came in at about 1.120, it was high. It really depends on the molasses, as to the sugar content (fermentables vs. nonfermentables). I tend to have a lot of brew projects on the go, so I didn't mind waiting for it to ferment out.

My most recent batch came in around 1.095.

I find the brewbelt on glass with a towel to insulate works well, ups the temp by at least +5 deg C. It's been extremely cold here lately, and I've been traveling (empty house = low thermostat) so this batch is still fermenting slowly (been almost 2 weeks), hopefully it will be ready for stripping this weekend.

-RoboStill

[chill]

Right. Molasses. I almost never use a hydrometer so I was not thinking about that. I doubt that a hydrometer will be of much use in a wash with a significant portion of molasses. The hydrometer just measures relative densities and there is a lot of unfermentable material in molasses. Even when all the sugar has been consumed you will likely still get a high reading. You will need to wait until it stops bubbling and starts to "clear" (really get darker as the light coloured yeast drops to the bottom). When the hydrometer shows no change for a few days it should be done. Or stuck. :-)

Chuck