ABV of molasses wash

[SomethingObscure]

I was wondering if this is a correct way of measuring the ABV of a molasses + sugar wash.

Not sure if my maths is right. Or if this kind of calculation is correct. I know that the SG reading can't be trusted with a molasses wash but I don't really understand why.

Day 1
6l Molasses + 26l water
Specific gravity = 1.082
Day 3
Specific gravity = 1.041
Alcohol content 5.38%
Added 2kg sugar + 2l water solution
Specific gravity = 1.055
Day 4
Specific gravity = 1.040
Additional alcohol 1.97%
Added 1.5kg sugar + 1l water solution
Specific gravity = 1.051
Day 8
Specific gravity = 1.028
Additional alcohol 3.02%
Total alcohol 10.37%

Is this just nonsense?

Cheers SomethingObscure

[zed255]

The issue with a molasses wash is there will be unfermentables that raise the SG reading, so a 1.090 or 1.100 may not be too high for an OG with an all molasses wash, where that would be very aggressive OG for other washes or mashes. Thing is those components will still be there at the end, so your FG will usually be elevated at the end of fermentation. The difference in SG from start to finish still tells you the ABV of the wash.

OG-FG*129=ABV still applies. I don't think it is inaccurate, just shifted up in gravity.

[8Ball]

1 gallon feed molasses + 3 gallons water is a pretty good ratio to use, and no more than 1.5# sugar per gallon as well. SG readings are elevated & skewed due to the unfermentables in molasses as stated earlier. If it doesn’t taste sweet, its done.

[SomethingObscure]

Thanks zed and 8 for the replies

That's is what I read about unfermentable sugars.

But I'm not sure you understood my questions correctly.
I've read that people estimate the alcohol content by calculating the theoretical sugar content of the molasses and additional sugar. I thought this might be because the hydrometer can't work when doing that.

6l molasses = 6 x 1.4 x 40% = 3.36kg sugar
Plus the 3.5kg sugar
Using the sugar wash calc in the parent site.
I noticed the my OP said 26l water when my notes says 24l.
6.86kg sugar to make up 36l wash = potential 11.2%

So that does mean that the relative specific gravity and the alcohol content is correct?

So are my calculations regards the additional alcohol created because of adding extra sugar is also no wrong?

The reason I'm doing these calculations is because 1. I want to start reducing the amount of sugar I use but want to compensate correctly with molasses. I guess I could just calculate weight of sugar x 1.4.

But 2 I would like to know how my ferments have actually gone. As 8ball say if it's dry it's ready but I guess being a newb getting as many indicators as possible helps me to understand what that actually means. I did taste my wash all the way through the fermentation and the changes in taste from day 6 to day 8 were very hard to notice with my experience. Molasses imparts a lot of flavour.

Sorry for all the follow up questions. I know experience will probably give me a lot of the answers but I just want my early fermenting and stilling experiences to be successful.

Cheers SomethingObscure

[NZChris]

The drop in SG is meaningful with rum and the OG is very important for the abv calculation.

My calculation for your final abv was very close to yours.

[Yummyrum]

SO , you are about right with your reasoning . .. but

An AVB around 11-12% might be OK when you have a high sugar to Molasses ratio . But an all Molasses wash with an AVB that high will have such a high initial gravity that the osmotic pressure in the yeast will be too high .

Most All molasses washes aim for an SG around 7-8% AVB .

Now also taken into account the addition of Dunder . Even with 10-15% Dunder, there will be a substantial increase in SG because Dunder , especially from All Molasses washes has a really high Specific Gravity . For example the Dunder off a recent second gen All Molasses wash had a gravity of 1.070 . This second gen all Molasses wash had an SG of 1.110 and finished at 1.048 ... a ABV of 7.99 ... close enough to 8%

So I ‘m using 15litres Molasses made up to 50 Liters ( 5 litres is Dunder)

Saltbushbill has arrived at a very similar amount in his All molasses recipe . He uses a little less than me 13.3litres per 50 litres .
https://homedistiller.org/forum/viewtop ... 3#p7530801

Also note : I don’t get hung up on exact amounts . I take my 20 litre pale into the Feed store and say “can you 3/4 fill it “ some times its a bit under , sometimes its a bit over . Regardless , the rum always comes out just fine

[Saltbush Bill]

As Yummy has said dont panic about gravity readings....stay with the quantities that he suggested and it will work fine.
If when done you taste it will be dry and tart.

[SomethingObscure]

Thanks Yummyrum and saltbush.

One more question. Is there any benefit in staging the molasses starting with say 5l molasses and 20l water and adding another 3l molasses (probably mixed with a litre of water) on day 2/3, then repeating a day or 2 later? Hopefully keeping the Specific gravity at lover levels.

Cheers SomethingObscure

[Saltbush Bill]

Ive never tried to do it that way, I think Crow may have done something like that once though.
I will suggest however that what ever yeast you use that you pitch on the heavy side rather that go to light.

[SomethingObscure]

thanks saltbush I'll see if I can find something about that.

So I'm using dried active baker's yeast. The last 2 ferments I used 50g each.

What would you call heavy?

For the next ferment I was going to try and save some yeast from the trub. Which I was hoping to start today but it's still bubbling slowly.

Cheers SomethingObscure

[Saltbush Bill]

When dealing with all Molasses I find that pitching new yeast every time makes for a faster start to the ferment and also a more vigorous and quicker ferment. Personally I prefer to dump boiling hot dunder ..or close to boiling onto the old yeast bed there by turning it to yeast food for the fresh yeast.

What would you call heavy?

Im not a numbers freak as you will find.....180L ferment would get two good hand fulls of bakers yeast.
Hold one hand semi cupped ..pour yeast from container with other hand.
Bakers yeast is cheap.

[SomethingObscure]

Thanks for all your help SBB.

I am working my way up to all molasses rum. I'm very new to distilling and want to build up a stock of sugar based molasses for sipping. I understand that the need for ageing is lessened.

I reckon I use just over half a handful per 35l ferment. So quite(very) heavy. But as you say bakers yeast is cheap. I think I'll follow your example and use the trub as food for the next ferment and just pitch new yeast.

Cheers SomethingObscure

[zed255]

I use fancy molasses that the label says is about 65% 'sugars', and I calculate based on that. I put 60kg of the molasses into my wash made up to about 200L with my usual 'nutrient soup' I put in anything sugar based. I pitch a full 113g (4oz) jar of bakers yeast (Fleishmans ADY bought in 2lb bricks), properly rehydrated. I think my SG starts at about 1.080ish, a little higher when I use some dunder. The wh usually ferments out close to 1.000 for me because I'm using higher quality lighter molasses. My yields suggest I'm getting about a 10% ABV wash or so.

[NZChris]

You can make great rum with anything from straight cane juice to all molasses, plus anything in between. My favorite commercial rums are made straight from cane.

Adding sugar to a molasses wash is only adding back something was removed at the sugar mill, so is not the same thing as adding sugar to a fruit must until you add more sugar than was removed from the cane juice.

[v-child]

I've had very good and consistent results with:
13 gallons water
2 gallons food grade molly
13 lbs sugar
one Tbsp citric acid for ph
one Tbsp DAP
Lemon juice for sugar inversion
1/2 gallon of molly added to boiler during spirit run

Invert that sugar, make stripping runs and one spirit run with molasses in boiler. This white rum has a bit of the molasses essence and is smooth after one week. You can oak if you want or mix in a bit of molasses, usually a Tbsp per quart and maybe a little vanilla to make a dark rum. Don't overdo it. One thing; this stuff takes forever to ferment, I had one batch going for almost three weeks before I got impatient. Goes like gangbusters for about a week straight at 72-75 F. I don't concern myself with the ABV/ OG/ FG, nor do I fiddle around with it either. Leave it alone until it's finished.

[SomethingObscure]

Thanks everyone for the info, advice and comments.

Today I stripped my first molasses and stepped sugar ferment. 6l Molli 3.5kg sugar and 27l water total. Got just 9 litres of 40%. I ran the first 4 litres slow and had a little sample (tempered) of the still and IMHO it's better than this stuff I buy.

I started my next with 8l Molli, 6l dunder (very hot) added to 1.5l trub and 25l water.

The SG was only 1.082, I'm worried that the new source of molasses from the feed store isn't as high quality as the last lot. But it did only cost 0.32 per litre. Thinking out loud and checking my note that's the same SG as the last lot and the ratio water & dunder : molasses is almost exactly the same.

I'm planning on stepping in another 5.5l molasses, 1.5l dunder, 2kg sugar and 1.5l water. Or maybe 7l molasses plus water and dunder. Not sure why I'm so scared or doing all molasses rum.

My second ferment which is almost identical to the first with a tad more sugar should finish very soon and will be stripped next weekend and the spirit run will follow.

So the next question / dilemma do I add dunder to the low wines and if yes how much? I should have 18l of low wines I really need at least 25l of charge for the still so was going to add water and or dunder.

I've read adding 10% dunder is pretty safe. That would mean at least 5 litres of water.

Buccaneer Bob says add the same about water as low wines but this feels excessive to me.

Cheers SomethingObscure

[SomethingObscure]

...

The SG was only 1.082, I'm worried that the new source of molasses from the feed store isn't as high quality as the last lot. But it did only cost 0.32 per litre. Thinking out loud and checking my note that's the same SG as the last lot and the ratio water & dunder : molasses is almost exactly the same.

...

Cheers SomethingObscure

Now having thought about this more. Wouldn't the dunder have a higher specific gravity than water?

So actually my fears might be right.

Cheers again SomethingObscure

[NZChris]

When I'm working out the ingredients for the next generation, I measure the SG of the dunder to help work out what effect it will have on the OG.

[SomethingObscure]

When I'm working out the ingredients for the next generation, I measure the SG of the dunder to help work out what effect it will have on the OG.

That's really helpful and interesting.

So my dunder is 1.060 and I added 6l with 25l of water.

So the way I would calculate the difference/effect would be.
(25 x 1.000)+(6 x 1.060) ÷ 31 = 1.012

Does that mean my OG would be elevated by 0.012. Or is that just bollocks?

Anyway not sure how I can use this number 1.060 to get my wash to a consistent value.

Or am I once again just over thinking it.
Btw the fermentation is going like a machine gun.

Cheers SomethingObscure

[NZChris]

I calculate it for the total volume of the wash, not just the water and dunder.

[Yummyrum]

Does that mean my OG would be elevated by 0.012. Or is that just bollocks?

Yes you are correct .You have just raised the. SG and FG by adding dunder .

Heres something else to think about .
Your dunder is 1.060 because of the un fermentable stuff in the Molasses from your last wash .

Now if you add it to another lot of Molasses ( that also contains more unfermentable stuff) the FG will be much higher .
So the Dunder from this wash will also have a higher gravity .

It is a compounding problem and very quickly especially in an All Molasses wash , you can have start gravities up around 1.130 and finishing at 1.070 .

It is a good idea to cut back to about 10% Dunder after about 3 generations .

[Saltbush Bill]

Or am I once again just over thinking it.
Btw the fermentation is going like a machine gun.

In my opinion you over thinking it.......youve already got a wash thats going like a machine gin.....use your senses to know when its done fermenting and run it.

[higgins]

I made my first rum just before I joined this forum a few months ago.

I heated 4.5 gallons (17 l) water to 120F (49C).
I power stirred in 11.5 lb (5.2 kg) demerara sugar until dissolved
I power stirred in 1 gallon (11.5lb, 5.2kg) blackstrap molasses until dissolved
mixed in 5 tsp DAP
Added and mixed in 5 gal ( 19 l) cold water
The total volume was now at 12 gallons (45.5 l) . My OG was 1.080
oxygenated, pitched 5 tsp rehydrated DADY

5 days, 1.005, 10% - net of 11.5 gal (43.5 l)
Although I didn't check pH, it had a pretty high attenuation so the fermentation was complete. My water is 7.4 pH, but has very low buffering capacity, so the natural acidity of the ingredients probably lowered the pH for the yeast for a good fermentation.
(in beermaking, If I brew a pale beer the mash gets to 5.4 just by adding the pale malt. But for a darker beer, the pH goes too low so I need to add some chalk [calcium carbonate] to increase buffering.)

With fairly wide cuts I netted 118 oz (3.5 l) @ 125p. Its been on used oak cubes (from my first bourbon's 1st 2 months) for 3 months. I sampled it last night and it has a lot of promise.

And now I have dunder for the next rum (have not checked SG) - I just picked up 5 gallons (58 lg, 26 kg) of the same molasses.

[SomethingObscure]

Thanks Chris, Yummy & SBB.

Once again you guys have helped me on the way to rummy bliss.

Heres something else to think about .
Your dunder is 1.060 because of the un fermentable stuff in the Molasses from your last wash .

Now if you add it to another lot of Molasses ( that also contains more unfermentable stuff) the FG will be much higher .
So the Dunder from this wash will also have a higher gravity .

Of course that make a lot of sense. But if you hadn't pointed it out I would have never figured it out for myself.

It is a good idea to cut back to about 10% Dunder after about 3 generations .

That's really useful info which I hadn't read anywhere yet. I'll be sure to do that.

In my opinion you over thinking it.......youve already got a wash thats going like a machine gin.....use your senses to know when its done fermenting and run it.

Of course you are right. But I'm a numbers man. (50g yeast is what I use. But you'll probably say a good handful). Counting is my second favourite pastime. I'm just worried that this molasses is a much cheaper source and I just can't believe that the fermentable sugar won't be less and I end up with a lower abv wash.

Anywho. More numbers for ya. SG was 1.043 so I've added another 7 liters of Molasses, 1.5 or dunder and 1.5 water. Giving me about 51l total wash now. SG after adding the extra dunder and molasses was 1.072. gunna let it run now.

Cheers SomethingObscure

[Stillhouse Sailor]

I use fancy molasses that the label says is about 65% 'sugars', and I calculate based on that. I put 60kg of the molasses into my wash made up to about 200L with my usual 'nutrient soup' I put in anything sugar based. I pitch a full 113g (4oz) jar of bakers yeast (Fleishmans ADY bought in 2lb bricks), properly rehydrated. I think my SG starts at about 1.080ish, a little higher when I use some dunder. The wh usually ferments out close to 1.000 for me because I'm using higher quality lighter molasses. My yields suggest I'm getting about a 10% ABV wash or so.

I have just started my first rum. I had hoped to do Buccaneer Bob's but accidentally ended up with baking molasses so it will obviously be different. Your post caught my eye because by luck my gallon of molasses diluted into my 19 liter (5 gallon) wash is almost exactly 10% of your batch. I had no dunder but I boiled 200g of bread yeast as per Buccanner Bob's and pitched 25g of bread yeast and a 20g packet of Still Spirits rum yeast. I pitched at 33 degrees and my fermenter has held at 30 degrees since then. My SG was 1.085 and 3 days later it is still fizzing happily at 1.012. I expect it to finish tomorrow. Since it looks like I will end up with a bit over a 10% wash I'm wondering if I should still add cane sugar as per the original recipe. I'm not sure what the fleischmann's bread yeast is capable of but the Still Spirits packet claimed up to 15%. Will I be sacrificing flavor to gain yield? BB's recipe yields five 750 ml bottles but that's from a 14% wash. At that ratio the 10% would only net me 3.5 bottles. I'd love any thoughts or advice.

[Saltbush Bill]

Since it looks like I will end up with a bit over a 10% wash I'm wondering if I should still add cane sugar as per the original recipe. I'm not sure what the fleischmann's bread yeast is capable of but the Still Spirits packet claimed up to 15%.

Pushing any ferment that you want to make quality booze from that high is not recommended.
Remember that we are trying to make quality here ...not quantity........even the big commercial guys who are after quantity don't push washes beyond about 9%.......do you think there might be a good reason for that ?
Still spirits products are aimed at the Quick /Easy/ Quantity, people, just because their yeast can reach high ABV's doesnt mean its going to make good Rum.
In the end its your Rum and your choice.