Of the whiskey in a barrel, what % of it is barley?

From what I understand, to make wort only 20% of spent grain is left. This leads to a figure of 80% of the grain dissolved in the wort.

After the yeast is added, the wort is distilled, separating the alcohols and leaving stuff behind. Seemingly the barley that has dissolved in the wort, does not get distilled and gets left behind?

What is the original ratio of water liters to kg of grain? After distillation, what % of the mixture is distilled off, and what % is left behind? What would the barley grain makeup of the whiskey mixture be, or just alcohol is distilled taking the converted barley sugars, but leaving all the "barley juice" behind?

  • I don't have an answer to your question, but barley does not "dissolve" in wort.
    – Denny Conn
    Jan 28, 2014 at 16:08
  • 1
    I don't know the answer either, but the type of whisky matters as to barley content. For example, bourbon must be made from at least 51% corn (maize). Furthermore, this is sort of a philosophical question. The whiskey starts as barley, water and yeast, and anything after that is a byproduct of those products. I will also note that you asked a similar question in February, and you may wish to refer to it for info on the whisky-making process. Jan 28, 2014 at 21:40
  • if barley does not dissolve in wort where does the grain mass go? The grains go in, and waste comes out. So what happens to the grain that is not waste?
    – Jon
    Jan 29, 2014 at 13:13
  • @Chino - if I asked a similar but different question, how can I find an answer to a different question? I clearly asked for specific ratios. Why is a ratio of liters to grain philosophical? If you want to be pedantic and include bourbon, why cant you then give some figures rather than just complain about a question?
    – Jon
    Jan 29, 2014 at 13:18
  • Sorry, not meaning to complain. I thought that some of your questions were answered in the info provided previously. I will take a stab at it. I think the answer is philosophical because it is like asking what percent of your body mass is composed of the eggs you have eaten - there is a transformational process that goes on, and it requires some subjective judgment to decide what remains part of the barley as opposed to something that is created by and is part of the enzymes or the yeast. Jan 29, 2014 at 15:36

2 Answers 2


According to this ProBrewer page about whiskey distillation, the initial mash is 100Kg of malted barley and 600 litres of water, for a 6:1 ratio. This yields 80 - 87 litres of 80 proof spirit.

As for the waste, U.S. 2-row malt has an extract potential of 79%, so 21% of the malt (modulo conversion efficiency), by weight, is not converted to sugar. That would be 21 Kg of spend grain in our theoretical batch. The malt will absorb some water (around 1 l/Kg according to BYO), so the total weight of the spent grain will around 121 Kg.


To sort of answer part of your question, in making scotch whiskey for example, the wort is fermented into a "Wash", which is double-distilled into a "new make spirit" containing 60-70% abv., which is then diluted with water to approximately 63.5% abv before being put into barrels for aging. Source: Wikipedia.

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