Knowing When the Hearts Begin

A distiller who has been letting the foreshots run to waste swaps the collection vessel at some precise moment. Why that moment and no other is the hardest practical question in distilling. Instruments you can read and instruments you smell get used side by side, and it helps to see first what hangs on the decision.

The fraction worth waiting for

The hearts, the middle fraction of a distillation run, hold the cleanest ethanol and the most desirable aromatics.¹

Start collecting too early and the sharpness of the foreshots rides in. Start too late and good spirit has gone down the drain. So the starting point needs instruments, and the first one is aroma.

First instrument: the aroma opens

Esters, formed when acids react with alcohols during fermentation and aging, give spirits fruity and floral aromas.²

The threshold of the hearts, as the nose reads it, is the point where solvent notes fall away and fruit and flower start coming through. A distiller repeatedly sniffing the spirit stream is taking measurements, whatever it looks like.

Second instrument: the proof slides

Running alongside the nose is a number. The strength of the distillate does not hold steady through the run, and its trajectory reports where the run currently stands.

The alcohol content of a spirit is measured as alcohol by volume, the percentage of ethanol in the liquid.³

A spirit hydrometer floats in the collection stream and the distiller watches how fast the reading slides. If aroma handles the judgment, the number handles the record: cutting at the same point as the last batch, run after run, comes from the numeric side.

Third instrument: conditions change the answer

Even from the same wash, changing the distillation conditions changes the composition of what comes over. Soju is a clean illustration.

In Korean soju the distillation method drives the aroma profile: atmospheric-pressure distillation gives earthy and yeasty notes with a grainy, barley hint, while reduced-pressure vacuum distillation gives a fruity, sweet character.⁴

What smells like hearts under atmospheric pressure and what smells like hearts under vacuum are different things, which means the cut point has to be retuned for the equipment and the pressure. This is why a cut recipe cannot simply be copied from another house.

An old hand trick that sharpens the call

Diluting a spirit with water lowers the ethanol concentration and softens the perception of harsh congeners.⁵

High-proof distillate hides its aromas behind alcohol burn. A few drops of water in the tasting glass lift that veil, showing the true character of what is coming over right now, and the trick has served as a supporting instrument for the cut for a very long time.

As a drinker you can run these three instruments in reverse. A spirit whose fruit opens cleanly in the glass reflects the aroma call, batch-to-batch consistency reflects the numbers, and a sharply defined profile reflects a deliberate choice of conditions.

• Tasting a white spirit, weigh the balance of solvent notes against fruit in the first sniff. It is a trace of where the hearts were started.
• Taste the same spirit neat and with a few drops of water side by side, exactly the way a distiller judges at the still.
• On soju or shochu labels, find the atmospheric or vacuum distillation note and match it against the aroma profile.
• Compare bottles from different batches of one distillery. The more uniform they taste, the tighter that house runs its numbers.