Aspects of Distillation (7): Sulfur Control!

19 May 2020
Introduction Aspects of Distillation” is a series the iStill Blog hosts. It aims to cover as many aspects as possible. Aspects of – you guessed it! – the distillation process. Think alcohol formation, flavors, mashing, distillery design … and more. In fact, if you have a suggestion, please email us the aspect you want us to dive into. Via Today’s topic? The importance of sulfur control. Sulfur control There are five things I want you to consider, when investigating the importance of sulfur control:
  1. Excess sulfur adds an off-flavor in your drink;
  2. Sulfur is a side-product of a bad ferment;
  3. Distillation concentrates sulfurs and its off-flavors;
  4. Copper catalyzes sulfurs and can neutralize those off-flavors;
  5. But copper comes with its own set of negatives.
Excess sulfer adds a harsh off-flavor to your drink. Harsh flavors are something you want to prevent. Therefor, it should be any distiller's goal to minimize sulfur formation. Sulfer is formed during fermentation. To be more precise: during bad fermentations, where temperatures, nutrient balance, and pH are off. Sulfur problems always result from poorly managed fermentations. Distillation concentrates sulfur contamination. It results in a higher alcohol percentage, more flavors, more sulfurs, and therefor more off-flavors, per milliliter. Copper catalyzes sulfur. A copper column or riser provides the surface area for sulfur and copper to react. As a result, copper stills are a medicine against sulfur contamination. Copper stills are a medicine for a bad ferment. Copper stills come with their own set of problems, though. Firstly, copper is a heavy metal and copper contamination in your drink creates health issues, such as non-alcoholic fatty liver disease. Secondly, copper and ethanol react (in your copper still and afterwards in your barrel or bottle) into ethyl carbamate. And ethyl carbamate is carcinogenic; it can cause cancer. Copper oxidizes. Copper particles get blown over into your drink, during distillation. The copper particle contamination, in itself and via ethyl carbamate formation, poisons your customers. So what you want, as a distiller that is both concerned about limiting off-flavors and limiting health issues among its customers, is a distillation process/machine that does not cause excess sulfur creation, and minimizes copper in the distillation process. Features & Benefits iStill Fermenters come with temperature and pH and SG control, to prevent sulfur formation. iStills are made from stainless steel and not from copper. You now know why. iStills come with specially designed copper waffles that can be placed at the bottom of the column in order to clean-up any sulfur you may encounter. The waffles provide the surface area of a copper column, while minimizing contamination risks.

Copper oxidation on a traditional still after just one run ...



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