Diluting: The final stage in making pure corn whiskey is to dilute the middle-run to between 40 and 50% alc/vol. It's a good idea to use distilled or deionized water as sold at supermarkets and pharmacies to dilute corn whiskey. However, many people simply use soft or filtered tap water.
Hard water should be avoided because, not only can it impart off flavours, but it can cast a white precipitate that often results in a turbid or cloudy appearance, or a chalky sediment at the bottom of the bottle. This precipitate is perfectly harmless, but is aesthetically unpleasing.
An example of diluting the middle-run to produce an excellent corn whiskey is to mix 900 ml of middle-run with 1100 ml of distilled water to produce 2L of 45% alc/vol corn whiskey.
Blending: Whiskey produced in a high-separation spirit still tends to have a very rich and intense flavour profile. This is because high-separation stills concentrate more of the desirable congeners into the middle-run while keeping the undesirable ones out, as opposed to lower-separation stills which lose more of the desirable congeners to the heads and the tails in the course of keeping the undesirable ones out. In the end, whiskey made in a highseparation still is clean and rich, but may or may not be too intense.
There are several ways to reduce the intensity of the flavour. One is to blend the whiskey with grain-neutral. Grain-neutral is about 95% alc/vol and is, for all practical purposes, almost pure alcohol that is very nearly devoid of all congeners.
The grain-neutral should be diluted with pure water to the same alcohol content as the whiskey. A small sample, say 30 ml (1 oz), of the whiskey can be blended 50/50 with diluted grain-neutral and tasted. If the flavour has become too insipid or is still too intense, the ratio can be adjusted slightly and tasted again. This is repeated until the right blend is achieved. Typically, the right blend is somewhere around 50/50.
There are certain advantages to blending with grain-neutral to reduce flavour intensity, and they are that the high-separation spirit still is eminently suited to producing pure alcohol and therefore grain neutral. Also, it's considerably easier to produce large volumes of pure alcohol than it is to produce large volumes of whiskey, so blending 50/50 or so with grain neutral becomes a very economical way to stretch your whiskey.
However, purists can quite rightly argue that once blended with grain-neutral, pure corn whiskey is no longer pure. So, in order to reduce flavour intensity without violating the purity of the whiskey, the distillation process must be adjusted.
First, by reducing the adjunct of feints, the intensity of the whiskey flavour will decrease. How much of course, can only be determined from one run to the next. But, don't reduce the adjunct of feints to less than 250 ml to 20L of strained mash.
If it's still too intense, start taking a slightly narrower cut. That is to say, let the heads run a little later and end the middle-run a little earlier. This way less congeners go into the middle-run and therefore the flavour is less intense.
And finally, you can run the flow-rate faster and thereby reduce the level of separation. This will cause more of the desirable congeners to bleed into the heads and the tails. Hence, behaving more like a low-separation still
Storage: Distilled spirits should be stored in glass, not plastic. Corn whiskey, by tradition, does not require maturing or aging in oak or charred oak barrels. Pure corn whiskey can be consumed right away. However, many distillers including the author contend that corn whiskey does improve for about five weeks after it's made. No one appears to have an explanation for this, and many people believe it's just folklore. The same, by the way, is also true for other non-aged spirits such as gin and vodka, and most producers of these spirits ensure their product is not shipped for about three months after bottling.
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