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Hi guys.

I have been distilling a poitín product since April commercially.  I had a few small issues along the way but was able to rectify the situation myself.  I have had 3 consecutive washes that didn't yield much spirit.  I have taken corrective measures to try and eliminate the problem.

The abv of the spirit drops relativley soon into the hearts run and the spirit becomes feinty.  Current yield is approximtately 30% of the usual yield.

The still doesn't have any leaks - I have checked over the gaskets for any wear and tear.  I'm using a stilldragon 3 plated column on top of a pot.

Wash:

I use 100% malt for my wash and distillers yeast.  Each batch of malt is tested by the manufacturer so this is unlikely to be the issue.

Mash rest temp - 62.5C, duration - 1 hour followed by sparging with hot water at 79C.  I have been relying on natural enzymes since starting and haven't had any issues.

My starting gravities range between 1.058 and 1.062.  Final gravity is generally 0.997 or 0.998.  For the past 3 washes, the gravity has been in the 1.000 region.

My S.G/ O.G suggest a good conversion of starches to sugars.  The final gravity is lower than usual but not proportional to the lack of yield.  Final PH on the latest wash was 4.75.  The previous wash had a PH of 3.42 suggesting a lacto infection.  Still expecting approximately 8%ABV.

Yeast is from Anchor Yeast.

Water is municipal and is consistent.  Carbon filter installed.

Cleaning regime - Caustic wash - 2% @ 70C plus. Followed by hot water rinse  Sterilisation done with paracetic acid 0.05% at ambient temperature.  There are no dead legs in the process that i have identified.  Heat exchanger is washes in reverse.

Last fermentation was very vigorous with quite a lot of foaming.

Any ideas what could be the cause?

 

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Hi.  I had read that thread but the problem isn't resolved.

I have adjusted my fermentation slightly in efforts to resolve the problem.  It hasn't worked however.

I cooled the wort to 22 C rather than the usual 19 C.

Yeast rehydration - 50:50 wort and wash mixture @36 C.  I boiled the wort used to rehydrate the yeast prior to this to kill any potential bacteria.  I gave the yeast 10 minutes in the mixture.  Yeast was begining to foam and become active.

Fermentation vessel is 1000 litres.  I only produced 500litres this time to see if the problem was resolved.

There are no apparent leaks in the still -   I have checked the gaskets and the condenser is working fine.

I'm running into feints prematurely - hearts cut was only 2.2 litres and it is usually 17 litres at an average of 81% ABV.

 

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Your first post almost suggested this was about a fermentation problem. But from your second post, this suggests an issue in distillation, as to where the cuts are? Are you still getting the right amount of total alcohol in hearts + feints, but just getting a bad cut? That is a very different situation than loss of total alcohol yield, which was how I read the initial post. If it is a bad cut, much more information would be required about the still and distillation method to provide any feedback.

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The fermentation appears to be fine so I'm confused.  In terms of distillation I haven't collected the entire feints cut to be able to say if I have the right amount of total alcohol.  From a brief calculation however the total litres of alcohol present is down quite a lot.  From using this type of still and being familiar with the sypmtoms of a weaker wash it seems like the wash is the cause.  I'm using a 250litre capacity pot with a 5'', 3 plate column with dephlegmator on top by Stilldragon.  I compress the tails cut at the begining and when the hearts fraction begins I raise the heating slightly and reduce the coolant to the dephlegmator.  I have tried increasing reflux to compress the hearts fraction but the hyrometer still rises and the flavour of the distillate is still of feints.

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How's the wash smell? A local brewery may have a lab you can ask nicely to make use of, or you could talk to one of the big labs and send out samples.

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Has there been any noticeable flavor or visible changes in the wash pre-distillation?  

How long does fermentation last before distillation - 2 days 5 days 10 days? 

I may have missed this but is the total recovered alcohol the same as earlier batches and it's the proportion of each cut that has changed?  When was the last time the still was cleaned?

The attenuation is good so the apparent alcohol shouldn't have changed appreciably.  Without further information, I'm guessing there is a vapor leak or it's an infected ferment.  Not much to go on at the moment though. 

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Has your fermentation lag or total ferment time sped up recently? Has your proportion of liquid heads increased? Have you changed nutrient loads? Or have you started a new lot of yeast? And has your finishing pH been really low or wonky?

 

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