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Rum fermentation questions

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I'm new, on my 9th batch of rum. My fermentation times have been all over the map, with no consistancy. Here's what my latest batch started like.

I began with 45gl of filtered water, which had a ph of 5.5, after 48 hours it was 2.6! That's with an og of 1090, 100 lbs of sugar. I pitched 1.6oz of lallemands rum yeast with 2oz of go ferm. I didn't rehydrate properly, but did add the yeast slurry from a previous batch and that may account for the drop in ph. I adjusted it up with sodium bicarbonate reasoning that the addition of sodium wouldn't be too great considering the source water had most of it removed. After 4 1/2 days its at 1072. I also aerated it during the first 2 days.

Is this slow for fermentation? Should I use more yeast? I addes fermaid K, 23g at the 24 hour mark, and was waiting for 1060 before adding the remaining 23g.

I started another batch, same source water, adjusted to 6.0ph and rehydrated the yeast with the go ferm exactly as it says to on their website. I aerated this batch only during the first 12 hours and added the fermaid k at that time. It was also 1090 og and has just started to ferment at 60 hrs. I stir twice a day to resuspend the yeast.

This is all done in stainless drums. I cover them with barrel covers and very tight rubber bands, with a vent to a bucket of water. The only thing I can think of that might be slowing them down is the temp of the water is 70f. Should I begin with a higher temp? When I rehydrate I did slowly add the room temp wort to bring the temp of the rehyrated yeast slurry to room temp.

I guess, how long should it take to fermnet out 100lbs in 45gl with 1.6oz of yeast? Any glaring errors? Thank you all.

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I've never worked with that yeast before but the specs indicate a rehydration temp of 104F and a ferm temp of 86-95F so that sounds like a part of the equation. Also you said you're fermenting in 45 gallon batches (1.7 hectoliters), the pitch specs are 10 - 50 g/hl so at 1.6 oz (45g) you're in the middle of that range and have some room move. Other thoughts, pH below 4 will shut most yeast right down so you may want to look at that. Also aeration, you really shouldn't aerate for days, the yeast needs the O2 in the first few hours after pitch to generate cell walls as it propagates (respiration phase) and after that you want it to go anaerobic (fermentation phase), if you keep pumping in air you do it at the expense of alcohol production. If you're using straight O2 you really want to watch it, if you're using filtered air you can play with it but I wouldn't think you'd want to go for more that an hour or two. I'm not a big believer in dried yeasts so recognize this comes with a bias but if you like working with this yeast, you may want to consider making a starter and pitching that rather than simply hydrating and pitching. Yeasts are living organisms and you can imagine dehydration beats the hell out of those little guys, so your viability probably isn't great to start, then you rehydrate in hot water, and toss it in a strong sugar solution where a good number of the little buggers explode from the osmotic stress so when all's said and done, you're probably looking at 50% viability of the volume you pitched. If you do a starter, you wake them up, give them some food and air, they get cooking, maybe pitch a little woo and start making new little yeasties and then when you pitch you've got a much stronger, much healthier population of yeast to work with.

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All very good information! I wasn't aerating for all that time, only for about 20 minutes with filtered air, a high volume though.

Anyway I can raise the temp? Electric blanket around the barrel? Starting warmer and keeping it there would be easy enough on the next one.

On making a starter, what sort of concentration of sugar should I use to help them get going? Or just leave them in the warm. Water with the goferm for a few hours?

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For the batches that are already going you could try an electric blanket just to get it up to temp and when the yeast gets going it'll keep the temp up on it's own. As for the starter, I'm sure there's a proscribed sugar concentration but I don't know what that is. I can say you'd want to go with a fairly low concentration for the sugar to keep the osmotic potential low enough that the yeast can take up the sugar easily (maybe go with a sol'n around 1.030 - 1.040). You can approach this with one of two goals in mind, 1) wake up a suitable pitch volume up, get it active and pitch or 2) wake up and grow a sizeable pitch volume. If the first just rehydrate, with warm sugar sol'n and when you see the yeast is getting active (head forms) then you can pitch away. If the second then you're looking at a few days of advanced planning: aeration, sugar sol'n, nutrient, stir, ferment, settle, then addition of more sugar, ferment, pitch. You can find some resources online to walk you through some different techniques and choose the one that best fits your set up. Healthy happy yeast is really the key to good fermentation.

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Ok, I got it all figured out and have been doing well. So that means time to change! I'm going to start using more molasses, about 40% of the wash. Should I continue to add dap as before? Or fermaid K? To me, I should be able to lower the FMK accordingly given that the molasses has nutrients in it, but the dap is unknown to me. Without it, the sulphide smell just awful. Thanks for the help so far!

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Was the big issue the low temp? When I have temperatures in the upper 70s, everything slows to a crawl. I don't use any molasses, just raw cane juice which is fairly rich in nutrients, but I have to believe 70 is too cold.

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I had two issues, the low temp was one. High sugar content was the other. With an OG of 1092, the yeast never had a chance. Starting at 1054 or so, fermenting to 1016 or so and then adding small 2nd and 3rd doses of sugar brought the time to 9 days from 23 days, with better yield too. I followed the dr cone method, while not using the heavy dose of nutrients. The ferment temps stayed in the 74 range, and I got about 90% of the theoretical yield. Plus it was easily repeatable and was able to reuse the yeast 3-4 times with only a one day addition to the ferment. Reusing did require higher start temps. I'm going. To try the same way with this new recipe, and see how it does.

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I've run my fermentations starting between 1.092 and 1.074 and never had any issue with my yeast activating. In fact, I get my SG below .995 every time. Have you tried different yeasts?

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I've tried 3 different yeasts, best luck with EC1118. I had multiple issues, but the use of dap, controlling ph, and start temp were chief among them. I'll start raising the OG little by little until I'm satisfied. Pitched a batch last night, it looked great this morning. We'll see soon enough.

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EC1118 seems to be the most consistent. Good luck.

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Ec1118 is a little slow starting but does a nice job

redstar champagne yeast is basically the same but is a little faster at initial propagation

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Sounds like they helped you pretty well. For what its worth We never ferment below 80f with rum. The best yeasts for rum like to be hot. I am not sure where you are located but during the winter months build a heat tent (plastic, 2x4s, and a space heater) to keep the ambient temp around the fermentors above 76. You should see full fermentations in 3.5-4 days. Molasses is widely inconsistent with how much dissolved solids each batch has so your end SG will vary from each batch of molasses. I am not sure if anyone has mentioned this yet, but use city water for fermentations. Yeast love those salts and that should fix your wide ph swings. This is all info that the guys at Lallemand gave me when I was starting out and trouble shooting.

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Hey guys, I'm thinking about getting into the rum game when we finally get off the ground... and I have a newbie question. Is there any flavor benefit to leaving any residual sugar in your wash? I notice Smoog goes down to .995 (no sugar left), which I understand is best for alcohol yield.... but would their be any sweetness or flavor to carry over if you left some behind, like in brewing?

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At .995 the rum was amazingly flavorful with a nice vegetal nose and finish. Remember, though, I am using freshly juiced cane from my own farm. I cut, juice, and pitch all in the same day. I have no experience with molasses or sugar washes. I don't see what value there would be in an unfinished ferment, but I would like to hear what others think.

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Ferment at 90 degrees, 20 brix, good strong yeast, and to start add a pound per 500 gallons of cap, 12 hours in, another pound. 48 hours you should be done. You can distill then or age it a day or so for more esters. Set the fermenter no higher than 4.

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Ph of 4, use citric to drop it first time, dunder the runs after that.

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What is the rate of citric (ie how many g/litre to change the pH from 5.5 to 4)? Also, is the reaction to citric the same for Evaporated Cane Sugar Juice as it is for molasses? I have found that you need MUCH less tartaric acid to drop the pH of ECJ than you need to drop Molasses.

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Thanks FLDME! I've been looking all over for a starting pH for mash bacteria suppression. I was going to use 3.6-3.8 which are the typical ranges for wine but I wasn't sure what to think, since it could drop and it ferments so fast. You divide up the DAP and nutrients so that it gets down to 2/3 starting brix? Assuming these ferments are done in 3 days would starting with nutrient be the right idea, vs. common 12 hour later methods for suppression of bacteria? I'm a little curious what methods work best for you guys? Do you guys use yeast starter slants or just hydrate dry yeast and let it rip?

http://distillers.tastylime.net/newSite/books/TAT4E/index.htm

On page 75 it goes into a good run down of parameters that come into play with what seems like issues with industrial alcohol although it says for rum. It doesn't say anything about adding in stages like with mead/honey but i can see this would make sense. With mead though its not as available, so it takes longer to ferment than monosaccarides.

Does anyone cold ferment? Seems like everyone lets it rip at above 85 but does anyone have any input on slower ferments at cooler temperatures sub 70?

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I have consulted on many rum projects. Best thing is ha e that dap dosed in at the start and feed it a couple times during the fermentation. Dry yeast will work fine. For a cleaner ferment add say a gallon to the hundred of heads to the fermenter. It will prevent aldehydes from forming. Also, another trick to keep bacteria out if shooting for a clean rum, dose it with Iso hop extract.

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Now THAT is interesting. Haven't thought of using my heads in the fermentation...would you add it once the krausen is up, or before the reproduction phase? Also, I have found hop oils to have a negative affect on my still...requires a mechanical wipe to my interior surfaces instead of a regular CIP. How much hop extract are we talking, here? I have quite a bit left over from some beer experiments....any other bright ideas?

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Add when you set the fermenter. And isohop extract is what to use. No more than 75 mls to 1000 gallons, 50 is plenty. Should not be any noticeable effect. Should not even smell.

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