Fermenting on the Grain?

Up to now I've been doing UJ & birdwatchers ferments and have seen fermenting on the grain mentioned quite often here as well as on other distilling forums.

Would someone please explain the process for me please.



  • edited December 2016

    Instead of removing the grain before fermenting, like you would do when making beer, the whole mash is moved to the fermenter and the yeast pitched.

    The rationale for this is the enzymes in the malt remain active through fermentation, which can increase alcohol yield, and anecdotally, many say this is one contributor to the defining flavor characteristics of American whiskies.

    Traditionally, if you are fermenting on the grain, you are distilling on the grain as well.

  • edited December 2016

    I suppose UJ is a kind of "fermenting on the grain", but it's really just corn flavoring rum.

    Corn is also a huge carrier of lacto, which is probably why the recipe works to create (along with backset) a very whiskey-like flavor. But that's beyond the question.

    Means nothing more than keeping the grain in the ferment.

  • @grim said: Instead of removing the grain before fermenting, like you would do when making beer, the whole mash is moved to the fermenter .

    So I would do a cooked mash or use enzymes then transfer all to fementer and pitch my yeast ?

  • edited December 2016


    Me, personally, I think it's easier to separate the grain from the wash right before distillation, especially if you are using corn, wheat, and rye. Nothing more complicated than a paint strainer bag and some squeezing.

    The viscocity after fermentation is significantly reduced, it's thinner, drains faster, doesn't plug everything up. You don't need to worry about contaminating your ferment by mucking around with trying to get it to lauter or drain-off. It's not sticky either.

    The other benefit is, if you are not as obsessive as a homebrew guy, you get the benefit of significantly better mash efficiency, especially if you use add some glucoamylase enzyme as insurance.

  • grim, I have a bag of glucoamylase enzyme on hand but so far have not done much research on how to use it. Care to explain further ? Thanks, friend .

  • You doing any all-grain mashes yet?

  • Nope. Have to learn the protocol.

  • There is nothing mythical about all grain mashing, when I started brewing beer I mashed in a beer cooler with a section of SS braid from a water heater hose, with the inner rubber hose removed, and had great success. It was as simple as heating water up to about 10 degrees F above what I wanted to mash at, and then adding the grain, stirring like a mad man, closing the lid, smoking a cigar, and daring the wort or wash off through the drain valve that had the SS braid attached.

    As I begin to understand the difference between mashing for beer and mashing for distilling I can see that the mashing for whisky can be a lot less picky and more easy going. And now that they make mesh bags that will fit in a cooler, you don't even need to do the SS braid thing.


  • @grim I completely agree,and that's how I do my henscratch bourbon.

    @Txbrewing what you say is all true, so long as you're only talking about barley malt and malt whiskey. Mashing corn, however is an ugly alternate reality, and the opposite of easy.

    Zymurgy Bob, a simple potstiller

    my book, Making Fine Spirits

  • Unicorn.....

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  • edited January 2017

    ZB you are correct, and I was speaking of just barley and wheat mashing. I will tackle corn mashes after i get another keg and burner.

    @grim as a beer brewer, fermenting on the grain is counter-intuitive to me, but I am open to new things.

  • Yeah, that and no boil. Everyone seems to freak out at the no-boil part.

  • Well, after some reading about how not boiling helps get better attenuation I can get on board with that..lol


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