Distillation’s primary goal is to separate alcohol from water and volatile components known as congeners. Congeners influence the spirit’s character and can come from various sources including cultivar used for mashing, fermentation procedure and yeast strain used, storage of fermented wash prior to distillations processes and maturation processes – keeping what you like and discarding what doesn’t suit. A distiller must find their balance by selecting only those congeners they desire while discarding what doesn’t fit their vision of taste and aroma.
However, this process is far more complex than it seems; each component has a specific boiling point and percentage in the vapor depends on its partial pressure. Lighter components with lower boiling points and lower vapor pressures will tend to evaporate first; however, heavy components still retain some portion of their vapor in distilled water at different rates than their lighter counterparts.
Distillers must select which parts of their “run,” (the mixture from their still), they wish to keep and how much of each. This process is known as making cuts.
Dependent upon the shape, heating method and angle of a still’s lyne arm; and depending upon whether vapor condensation occurs through tubes or worms – all these factors will influence the final spirit produced.
An integral component of distilling is keeping tabs on the temperature, as changes to it indicate which compounds are being vaporized and condensed. At some point, however, the temperature will stabilize and you can switch receiving flasks for different pure fractions.