Distiller's Log, Feb 4th 2012
There isn't much
construction yet as we're waiting on inspectors, electricians etc, so I
thought I would do a technical post. I will be posting with info on our
spirits, but also on distillation, aging, tasting, fermentation,
etc...so here's one on distilling.
Distillation is how you turn wine or beer into brandy, whiskey, or
vodka. It's defined as the separation of volatile compounds by their
boiling points. I'll start out with high school chemistry and take it
from there. The boiling point of a mixture falls somewhere between the
individual boiling points of the components within the mixture. The
greater the proportion of one component the closer to it's boiling point
will be the mixture.
Boiling point Ethanol: 78.6C
Boiling point Water: 100C
All ethanol distillation occurs with the vapor and the liquid somewhere between these two temperatures.
still is basically a pot with any number of things hooked up to it. In
the simplest stills there's a helmet (a big open copper top) and then a
condensor (something with cooled metal surface for the vapor to
condense on). These are called alembic stills and are used to make
Scotch and other whiskies, rum and many of the more flavorful spirits.
They are made of copper because copper is a reactive metal and is great
at removing unpleasant compounds from the vapor. Alembic stills are
excellent for flavored spirits as they don't have much tech attached for
purification and allow a lot of flavor to come through. The downside is
that there isn't much control or ability to alter the distillation
process. It produces what it's going to produce and most of your product
is controlled by the fermentation process.
complex setup would have a column of some kind after the pot and helmet
or rather than a helmet. The column has plates inside, on which the
vapor condenses and then revaporizes. Each time this happens the
percentage of alcohol in the vapor goes up. This is called
rectification. Given enough plates you get 96% alcohol, which is the
highest alcohol you can get with distillation alone. A short column of 3
or 4 trays can be used to make more lightly flavored whiskey than an
alambic still might make, or it can be used to make a spirit that is
very light and clean, with high rectification. The short columns are
indespensible for the production of eau de vie, brandy, and other fruit
fermented spirits, and are also used for whiskey, rum, etc.
the course of distillation there are a series of cuts made
chronologically. These are made differently in different traditions but
the principles are the same.
1. Heads cut
consisting of ethanol and water, the heads cut is the first stuff to
come out of the still and has a collection of other components that have
lower boiling points than ethanol. Acetaldehyde, Acetone, Ethyl
acetate, Methanol among others have flavor and aroma characteristics you
might describe as fruit, floral, finger nail polish remover, marker, or
solvent. Although some of those sound strange for something you drink,
they are an important part of the flavor/aroma profile of many spirits.
Most of this early cut is removed but low concentrations of these
compounds are either included or reintroduced to later distillations.
The bulk of the heads cut is just disposed of. We use ours as a spray on
2. Hearts cut
This is the
spirit itself. The distiller makes this cut by smell and taste and this
is the only part of the distillation you will ever drink. Many
distillers make a big deal about only including the hearts cut of a
distillation in their bottle. If they include anything else no one will
buy what they're selling. The hearts is also primarily ethanol
and water but there are hundreds of compounds that can be solubilized in
either the water or the ethanol to provide flavor and aroma.
tails cut is disposed of like the heads, or rectified to neutral for
use in gin or for fortification. This cut has many alcohols in it you
wouldn't think you'd want such as propanol, butanol, isoamyl alcohol.
These sound terrible, but if you drink whiskey, rum, or basically
anything other than vodka, you are enjoying the lovely flavors these
alcohols provide. Again this cut is made at the distiller's discretion
and anything that gives you a serious headache had a tails cut that was
In the figures below you can see some
data collected during a vodka run. The x-axis is time and the y-axis is
concentration. What you're looking at is the change in congener (heads
and tails) concentration during the vodka run. The heads figure stops at
250min because not much other than ethanol and water are coming out
until figure 2 starts around minute 620. This data was collected using
Gas Chromatography which is a great way of looking at these kinds of
The heads cut was finished at about 35 minutes
and the tails cut started at 640. On the heads side clearly some of
these compounds make it into the distillate but by the time they are
diluted into the hearts, the concentrations are very low.
the distillation and the cuts are very important many mistakes are made
in the fermentation. This is really where all of the flavors are made
and by the time it's reached the still, many serious fermentation faults
just can't be fixed.
There are other things within the
alcohol water matrix. Remember those two temps above between which all
ethanol distillation occurs? Some compounds with much higher boiling
points can be found in spirits because they are soluble in one of the
liquids. For example fatty acids with boiling points as high as 200C can
be found in whiskey because they are soluble in alcohol, so they travel
over with the vapor. These can provide flavor and/or mouthfeel and are
important in aged spirits. Another example would be phenolics from the
grain. These travel over and produce the grain flavors, and tasting
notes like spice, caramel, smoke, and many more.
Thanks for reading,