How does pH effect yield during distillation?

edited April 2023 in Recipes

I was wondering if anyone had any experience with changing the pH of a wash before distillation. Either lower of higher and did this have an effect on the final product?


  • I have no experience on this one, but my gutfeel tells me that it will have no significance on yield. I don't specifically believe taste either unless it's backset.

    However that said, some have said that addition of baking soda prior to a spirit run assists in heads compression but that is not confirmed and is possibly more hearsay. On the other hand, addition of backset is beneficial to minerals and taste.

    Be interesting to hear from others whom have knowledge.

  • Simple, useless answer is yes, of course any pH mediated reaction that takes place during distillation will be impacted if you are manipulating the pH.

    The standout is Fischer esterification. Adding a mineral acid like sulfuric acid will result in greater levels of esterification and ester in the final product than acid. Old process documents on Jamaican high ester rums sometimes show sulfuric acid additions pre-distillation.

    There are likely others beyond this, but it's not as well documented/understood as that.

  • A small, possibly negligible, amount positive I would believe for some products. For grains/fruit you probably will as they are usually coated in yeasts/bacteria so acidifying the mash would help fight off some of the infection stuff. Again, no idea how much but something?

    With a higher pH yeast grows faster. A by product of that growth are esters as they are a step in building cell walls.

  • sulfuric is better than citric , both in reading and in my personal experience... I use Sulfuric from the pool supply store, it is 35% or so... does not take much to get a .5 pH reduction of the initial wash

  • 100% sulfuric. Highest yield requires a mineral acid like sulfuric.

  • Thank you.

    I was wondering on when to add the Dunder. I used to add it to the mash after a day's ferment and the yeast had established already. Subsequently my dunder pit turn bad to the smell and I wouldn't want to taste it straight up. Doing a little research on the old Jamaican dunder pits its said that they were that bad but I didn't want to ruin a whole batch. Adding the dunder in the ferment drops the PH quickly which is a whole different problem. I was wanting the add the addition of the dunder post fermentation but predistillation which would lower the ph. significantly. So was wondering what effect this would have. The basis of thinking was that the longer the two components were in contact the better the esterification would be.

  • @RumBumm said: I was wondering on when to add the Dunder.

    I always added my dunder or muck pit right before the wash went into the boiler. Then ran it in reflux for an hour. I just wanted the esterfication from the muck, not any influence on my fermentation.


  • My understanding of studying the Jamaican processes is that dunder (clean stillage) is added the the beginning of fermentation, cane acid (dunder, skimmings, and cane trash thats infected with a homofermentitive strain of lactic acid bacteria that produces lactic and aceditc acid) is added towards the end of primary fermentation, and muck (dunder with trub, fruit trash, and a clostridium bacterium infection) is added when you put the wash into the boiler.

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