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?