Double Distilling for Whiskey etc

Here we try to replicate the traditional style as used in commercial distilleries world wide. See Making Whiskey - A Personal Experience by Roger Dowker for a detailed description of the commercial process, including when the various cut-off points are.

The trick to this appears to be the stuff legends are made of, and closely guarded by those who know. It's the matter of how much of the first condensate, or foreshots, to discard and how much of the middle cut to keep before discarding the last runnings, or feints.

Steve writes that its difficult to do this by temperature alone, nor to have a single set of guidelines ...
    The cut points have to be determined either organoleptically (by taste or smell) which takes experience, or by vapor temperature. The wash itself varies too much (say between brandy and whisky) in levels of fusels, esters methanol and other volatiles to make any simple volume rules across such a wide range.

For the various %'s at which to do the "cut", Donald advises to use a great hydrometer with 0.5% or greater calibrations for best results, and suggests ...

MashFirst DistillationSecond Distillation
Grainsto 18% (98 °C)85%-58% (80.5 °C - 92 °C)
Fruitto 25% (97.5 °C)85%-60% (80.5 °C - 91.5 °C)

When about 2/3 - 3/4 of the way through the middle run, and approaching these cut points, start collecting the spirits in smaller collection containers, and smell each of them seperately. The flavour will change from that of the neutral spirit, to more and more of the flavour coming through. This will intensify, but then start to become bitter. You need to work out when to make your "cut" during this period, but do so before it gets to the bitter stage. After making the cut, keep collecting (seperately) the feints up to about 92 °C, and add these to future runs.

For a reasonable whisky without the long term maturation try this :
  • Brew an all grain or malt extract wash using a good yeast like turbo, hyper or one of the wyeast family. Go for no hops and don't add sugar.
  • When attenuated, load the wash into your POT still or DE-REFLUXED reflux still with the feints (see later).
  • Run out about one third of what you loaded in, as "low wines". Different distilleries tend to get between 18-25% on these.
Repeat the whole exercise several times until you have enough of the low wines to fill your still. (Commercial distilleries get around this by using a smaller still for the low wines).

Load the still with the low wines and set it going.
  • Throw away the first 200 mL. These are the "foreshots", containing methanol as well as other low boiling point compounds. You need to discard more than the usual 50 mL, as pot stills are less discriminating then reflux stills. Watch this run with more care than before - it will proceed quite a bit faster !
  • The next 5 litres is the good bit that you're after (approx 75%, stop when getting below 60% ? - this is the trade secret of distilleries, as it determines the taste of the distillate). Update ! - see Donalds recommendation above of 58% for grains and 60% for fruit.
  • The following 10 litres (the "feints") - save and put back into wash run next time.
It's this re-cycling of the feints each time that does the magic, as they contain the higher alcohols (fusel oils), and esters.

You can now take the 5 litres, flavour it a little bit, put it in a small keg or flavour it with some oak essence. If kegging cut with water to around 40% or the angel's share will get too much. Don't charcoal filter or polish this spirit, as all the tasty bits you've just worked so hard to obtain will go too.

In theory, lets say I was the distiller at Ardberg with one wash still and one spirit still, I would run all the spirit out of the washstill as low wines, load this into the spirit still and run foreshots, high wines, with a cut at betwixt 65/60% then the rest as feints down to X %. The feints could then go back to the wash still or spirit still for the next batch. If I were at Ardberg, I would probably run them back to the wash still.

In order to get congeners, as opposed to a neutral profile it is important not to have a definitive reflux device in the steam path - enough refluxing will occur within the headroom, the "roof" of the still body, the lyne arm or equivalent. Make sure the still is only filled to about the three quarter mark.

As the weather becomes hotter and hotter in the southern hemisphere pot distillers put less wash in the body of the vessel thereby allowing more head for particulates of the solid variety to not be entrained [carried over] into the distillate. If you have variable control throttle back a bit.

Jack adds regarding the tossing of heads...
    Typically, you only throw away the first 50 to 100ml on the second distillation, not the first. Because of the higher alcohol concentration, the methanol will be more concentrated as well. This makes getting rid of all of it more likely on the second run.
Jack compares the cuts ...
    The "middle cut" proportions that are listed in Ian Smiley's corn whiskey book mathmatically conform (almost exactly) to the yield data I sent you out of that Japanese Scotch book - About a 57% middle cut.

    I also learned that these "middle cut" numbers are good for any volume, and any still- I have made a corn whiskey and have "made the cut" according to Ian Smiley's numbers- but I did this with an ice-water-wok still, and only 2-liters of freeze-concentrated mash (equal to 4 liters unfrozen). It comes out to:
    Foreshots23 ml(3.1%)
    Heads130 ml(17.4%)
    Middle Run428 ml(57.1%)
    Tails168 ml(22.4%)

    all adding up to the 750ml bottle I normally get of pretty rough stuff out of this still. Just by applying the middle cut numbers, I get just over half as much- but it is a LOT better.
Jack adds ...
    [for typical scotch] ... The beer still is loaded with 100 volumes of wash at 8%abv, this is distilled until you get 35 volumes of low wines at 20-23%abv. You will then mix 22 volumes of feints (from a previous distillation) at 28-30%abv, giving you 57 volumes at 23-25%abv, which you load into the spirit still. You then distill the low wines, collecting the fraction coming over at 75%abv (methanol is thrown out, anything from the initial starting % down to 76%abv is tossed into the feints tank), and you stop collecting at 55%abv, giving you 11 volumes of spirit at 68-70%abv. Anything that comes out of the still at below 55%abv is saved, and thrown into the feints tank. In the first distillation you should be left with 65 volumes of "pot ale" at the bottom of the still with less than 0.1%abv to be sold as high protien animal feed. In the second distillation, you should be left with 23.5-24.5 of spent lees at less than 0.1%abv, that is diverted to waste water treatment.

    By the way, even the Scotch distilleries are now admitting that yeast strain makes a difference in the spirits' final flavor. They figured this out after a couple of research chemists at a distillery made a batch, then filtered ALL the yeast out, and distilled it. After comparing the resulting spirit with regular (unfiltered mash) spirit, they found (under liquid chromatography), that the yeast has a BIG influence on flavor due to the long chain fatty acid esters that are found in yeast do distill over into the spirit- this is, in fact, the cause of cloudiness in spirit thats been run through a potstill only once, not the heavy alcohols as was once thought.
Jack also adds about Glenmorangie...
    They take only 1/5 of the second run as middle cut spirit- the numbers I posted are for the more common 1/3 middle cut- sorry, all of those wanting Glenmorangie should work just like [above], but only collect 6.6 volumes of spirit, after the heads are thrown out, and the >76% fraction has been sent to the feints tank, other than that, it's the same. This should average a final spirit strength of about 70%abv, and your Glenmorangie cutoff point should be when the spirit coming out of the still drops to below 65%abv.


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