Juniper berries, a key component of the botanical mix of gin production, has over 100 individual compounds comprising different chemical classes, each with their own physico-chemical and olfactory parameters. The concentration of these compounds in the final product is determined by the amount of botanicals used in the distillation and volatilities of each of these compounds. Volatility is a measure of the partial vapour pressure of a compound in a mixture. Raoult’s Law describes the simple relationship, whereby the partial vapour pressure relates to the pure component vapour pressure (as a function of the boiling point of the compound) at the pressure of the distillation process (usually atmospheric) and its solution concentration. The latter is determined by the concentration of the compound in the botanical substance, the amount of botanical substance used, and the rate of extraction of the compound from the botanical into the alcohol/water solution being distilled.
This paper presents data on the concentration of key gin volatile present in juniper berry and coriander seed during gin distillations as a function of the placement of the botanicals in the still (e.g. pot, gin basket, Carter Head) and the starting concentration of alcohol in the pot. This data can then used to provide information on optimal botanical loads and distillation times for gin production in relation to the composition of volatiles in the distillate.

Key words: gin distillation, distillate composition, botanicals