How does steam distillation of botanicals work without alcohol as a carrier?

The chemistry relies on Henry's Law and vapour pressure interactions. Aromatic compounds that are normally non-volatile at 100°C become volatile when they form an azeotrope-like system with water — their combined partial pressures exceed atmospheric pressure before either component's individual boiling point is reached. This allows lavender's linalool (boiling point 198°C) to distil with steam at around 100°C. The technique has been used industrially for essential oil extraction for centuries — it's the method behind most rose attar, lavender oil, and eucalyptus oil production.

For non-alcoholic spirits, steam distillation is used to capture specific botanical distillates that are then blended. The key limitation is selectivity: steam distillation strongly favours monoterpenes (small, relatively volatile) and somewhat disfavours sesquiterpenes (larger, heavier, less volatile) and non-volatile polar compounds. Botanicals like juniper, citrus peel, and lavender respond excellently. Botanicals like gentian root (bitter compounds are non-volatile, polar, high-molecular-weight secoiridoids) do not benefit from steam distillation — they require water or solvent extraction instead.

The hydrosol fraction — the aromatic water — is increasingly valued in zero-proof production. Rose hydrosol, orange blossom water (eau de fleur d'oranger), and lavender hydrosol contain the water-soluble polar aromatic compounds that don't appear in the essential oil. These can be used directly as drink components — Middle Eastern and North African cuisines have used them for centuries in drinks (sharab al-ward, faloodeh) that serve as ready-made templates for zero-proof drink innovation.

Related questions